Final Report

Orangutan Population
and Habitat Viability Assessment

23-27 May 2016

Bogor, Indonesia
 Final Report
Orangutan Population and
Final Repor Orangutan Population and Habitat Viability Assessment 2016

Habitat Viability Assessment

23-27 May, 2016

Bogor, Indonesia

Map credits: Forum Orangutan Indonesia

© Photo Credit : FS Ngindang (Mensiau Community, Kapuas Hulu, West Kalimantan)
© Copyright Ministry of Environment and Forestry of Indonesia 2017

A contribution of the IUCN SSC Conservation Breeding Specialist Group

Utami-Atmoko, S. Traylor-Holzer, K. Rifqi, M.A., Siregar, P.G., Achmad, B., Priadjati, A., Husson, S., Wich,
S., Hadisiswoyo, P., Saputra, F., Campbell-Smith, G., Kuncoro, P., Russon, A., Voigt, M., Santika, T.,
Nowak, M., Singleton, I., Sapari, I., Meididit, A., Chandradewi, D.S., Ripoll Capilla, B., Ermayanti, Lees,
C.M. (eds.) (2017) Orangutan Population and Habitat Viability Assessment: Final Report. IUCN/SSC
Conservation Breeding Specialist Group, Apple Valley, MN.

IUCN encourages meetings, workshops and other fora for the consideration and analysis of issues related
to conservation, and believes that reports of these meetings are most useful when broadly disseminated.
The opinions and views expressed by the authors may not necessarily reflect the formal policies of IUCN,
its Commissions, its Secretariat or its members.
The designation of geographical entities in this book, and the presentation of the material, do not imply
the expression of any opinion whatsoever on the part of IUCN concerning the legal status of any country,
territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries.

Copies of the Orangutan Population and Habitat Viability Assessment 2017 can be downloaded from:
www.cbsg.org and forina.or.id
 Population and Habitat Viability Assessment
23-27 May, 2016
Bogor Indonesia

The Directorate General of Natural Resources and Ecosystem

Conservation, Ministry of Environment and Forestry of Indonesia

In collaboration with:
Forum Orangutan Indonesia – FORINA
Orangutan Foundation-United Kingdom
IUCN SSC Primate Specialist Group
IUCN SSC Conservation Breeding Specialist Group
 Content

Content 5
Acronyms And Abbreviations 6
Executive Summary 9
The 2016 PHVA Workshop 11
GIS And PVA Models 14
Results 14
Recommendations And Next Steps 21
Steering Committee Notes 23
Threats To The Conservation Of Orangutans 27
Habitat Loss And Degradation 27
Hunting, Illegal Capture And Conflict 30
Fire 31
Small Population Size, Reintroduction And Disease 32
Potential Mitigation Strategies 33
Working Group 37
Pongo abelii 37
Pongo pygmaeus morio 40
Pongo pygmaeus pygmaeus 43
Pongo pygmaeus wurmbii 47
Orangutan Population Viability Analysis Modelling Report 51
Introduction 51
Model Parameters And Input Values 53
Sensitivity Testing 56
Impacts of Population Size: Defining Minimum Viable Population Size 59
MVP Under Alternative Conditions 62
Viability of Sumatran Orangutan Populations 66
Viability of Bornean Orangutan Populations 76
Summary of PVA Modelling Results 86
Summary 89
Orangutan GIS Models 91
Introduction 91
Approach 91
Current Orangutan Numbers For Borneo 92
Insights 92
Estimated Yearly Deforestation Rates For Use As Threat Estimates For The Pva Models 93
References 94
Appendix I Gathering Information 97
Appendix II. PHVA Collaborators 99
Appendix III. Data For Pongo abelii 103
Appendix IV. Data For Pongo pygmaeus morio 109
Appendix V. Data For Pongo pygmaeus pygmaeus 118
Appendix VI. Data For Pongo pygmaeus wurmbii 121

Orangutan Population and Habitat Viability Assessment 5

 Acronyms and Abbreviations
AAC Annual Allowable Cut
BKSDA Nature Conservation Agency; Indonesia (Balai Konservasi Sumber Daya Alam)
BMP Best Management Practices
BNF Borneo Nature Foundation
BOSF The Borneo Orangutan Survival Foundation
BPN National Land Agency
BT Batang Toru
BTNK Balai Taman Nasional Kutai
BTNS Balai Taman Nasional Sebangau
BTNTP Balai Taman Nasional Tanjung Puting
CBSG Conservation Breeding Specialist Group (of the IUCN SSC)
COP Centre for Orangutan Protection
EL East Batang Toru
ERC Ecosystem Restoration Concession
FFI Fauna and Flora International
FMU Forest Management Unit (general)
FORINA Forum Orangutan Indonesia
FR Forest Range
GCN Global Conservation Network
GD Gene diversity
GIS Geographic Information System
HCV High Conservation Values
IUCN International Union for the Conservation of Nature
LPF Low pole forest
K Carrying capacity
KHDTK Special Purpose Forest Conservation District
KPH Forest Management Unit (Indonesia)
MSF Mixed-swamp Forest

6 Orangutan Population and Habitat Viability Assessment

MVP Minimum viable population
N Population size
NR Nature reserve (CA)
NP National Park
OFI Orangutan Foundation International
OF-UK Orangutan Foundation UK
OU Orangutan
Orangutan Strategic Action Plan (for the Trans-boundary Biodiversity Conserva-
OUSAP
tion Area in Sarawak)
PE Probability of extinction
PF Protection forest (HL)
PHVA Population and Habitat Viability Assessment
PVA Population Viability Analysis
RMU Rimba Makmur Utama
RRC Rimba Raya Conservation
Satgas PMH Mafia Eradication Task Force
SD Standart
SSC Species Survival Commission (of the IUCN)
ST Sensitivity test
SVLK Timber legality certificate
TNC The Nature Conservancy
UNAS Universitas Nasional
UNFCCC United Nations Framework Convention on Climate Change
WCS Wildlife Conservation Society
WR Wildlife reserve (SM)
WS West Batang Toru
WWF World Wide Fund for Nature
YIARI Yayasan IAR Indonesia (NGO, orangutan rescue and rehabilitation)

Orangutan Population and Habitat Viability Assessment 7

8 Orangutan Population and Habitat Viability Assessment
 Executive Summary

Figure 1. The distribution of Sumatran and Bornean orangutans based on Wich et al., 2016 (Sumatra)
and on deliberations at the 2016 Orangutan PHVA (Borneo).

Orangutan Population and Habitat Viability Assessment 9

Orangutans occur on the islands of Sumatra The results of the 2004 PHVA have provided
and Borneo (see Figure 1.). These iconic important input for government policies, such
Indonesian species are the only great apes as the Conservation Strategy and Action Plan
living in Asia. Both Sumatran and Bornean for Indonesian Orangutans 2007-2017, the
orangutans are classified as Critically Sabah Orangutan Action Plan 2012-2016
Endangered by IUCN (IUCN 2016) and are and the Orangutan Strategic Action Plan
protected by Indonesian and Malaysian (OUSAP) for the Trans-boundary Biodiversity
law. However, the development of forest Conservation Area in Sarawak. In Indonesia,
resources, which assists Indonesia and the official launch of the policy, in December
Malaysia to achieve economic development, 2007 by the President of the Republic of
has resulted in the loss and degradation of Indonesia in Nusa Dua, Bali, in a parallel
forests over the last 25 years, threatening workshop of the Conference of Parties (COP)
the habitat of orangutans. This threat, in XIII–United Nations Framework Convention
concert with others, such as the pressure of on Climate Change (UNFCCC), was a real
increasing human population, forest fires, oil political commitment by the government
palm plantations, mining, poor enforcement of the Republic of Indonesia to conserve
of wildlife law, illegal hunting/trade, and orangutans. The policy, which was established
inconsistent policies on the management and by the Ministry of Forestry Regulation Number
functions of forested areas, threatens the very P.53 Menhut-IV/2007, also encourages
existence of these species in the immediate coordination of orangutan conservation.
future. Forum Orangutan Indonesia (FORINA), a
central coordinating body for orangutan
Wild populations of orangutans are in steady
conservation established on 25 February 2009
decline. This situation has long attracted
with orangutan conservation communities,
attention from stakeholders, and in 1993
has regularly evaluated the implementation
orangutan scientists and conservationists
of the action plan, including in 2009, 2010,
conducted the first Orangutan Population
2011, and 2013. Meanwhile, WWF-Malaysia
and Habitat Viability Assessment (PHVA),
has become the key implementing partner
facilitated by the Conservation Breeding
of the Sabah Orangutan Action Plan 2012-
Specialist Group (CBSG) of the IUCN SSC.
2016, and WCS Malaysia has become the
These assessments were updated and
key implementing partner of the Sarawak
expanded at a second PHVA held in 2004
Orangutan Strategic Action Plan (OUSAP) for
that integrated estimates of human-based
the Trans-boundary Biodiversity Conservation
threats, such as current and projected land-
Area.
use patterns and illegal removals, into
viability projections. Computer models were In 2016, after more than 10 years since the
used to evaluate current and future risks of last PHVA, the Directorate General of Natural
population decline or extinction under current Resources and Ecosystem Conservation, in
and alternative management scenarios. partnership with Forum Orangutan Indonesia
(FORINA), the IUCN SSC Primate Specialist

10 Orangutan Population and Habitat Viability Assessment

Group and the Orangutan Foundation-United grant from Arcus Foundation. The resulting
Kingdom (OF-UK), conducted the third PHVA assessment, which is documented in this
for orangutans. The IUCN SSC Conservation report, will provide important input for the
Breeding Specialist Group provided neutral revision of the national conservation strategy
facilitation and population viability analyses, and action plan, the planning period for
and the workshop was made possible by a which ends in 2017.

The 2016 PHVA Workshop

c Arif Rifqi

Figure 2. Opening Orangutan PHVA Workshop 2016 by Director of Biodiversity Conservation of the
Ministry of Environment and Forestry.

From 24-27 May 2016, 84 experts from 50 setting the scene for workshop discussions.
organisations gathered in Bogor, Indonesia, to A series of brief presentations aimed to bring
share information on orangutan distribution, participants to a common understanding
abundance, threats and conservation of the current situation for orangutans, the
activities. On Day 1, the opening address was challenges ahead, and to some of the tools
given by Ir. Bambang Dahono Adjie, MM, available to help plan conservation action for
MSi (Director of Biodiversity Conservation of the species.
the Ministry of Environment and Forestry),

Orangutan Population and Habitat Viability Assessment 11

 List of presentations:

• Introduction to IUCN SSC CBSG workshop processes (CBSG, Caroline Lees)

• Status review: a summary of the range-wide status of orangutans (FORINA-UNAS,
Sri Suci Utami Atmoko)
• Progress report on the implementation of the Indonesian Orangutan Conservation
Strategies and Action Plan 2007-2017 (Ministry of Environment and Forestry
representative, Puja Utama.)
• Mixed survey analysis revealed declines in abundance of Bornean orangutans
(Pongo pygmaeus) (Queensland University, Truly Santika)
• Modeling the density distribution of Bornean orangutans (Max Planck Institute,
Maria Voigt)
• Overview of past and current orangutan Vortex models (IUCN SSC CBSG, Kathy
Traylor-Holzer)
• Following the presentations, participants began work to:
• Update the collective estimate of the distribution and status of orangutans.
• Review and revise what is known about the issues threatening orangutans.
• Review and revise recommendations for priority conservation strategies for the
four taxa.

Working groups were formed around each a. Regional units: large, relatively well-
of the four taxa. Orangutans are currently defined regions within the range of
distributed across a large geographic area. each taxon.
Within this area there is considerable variation
b. Meta-population units: areas within
in orangutan numbers, densities, degree of
regional units bounded by rivers, roads
population fragmentation, and nature and
and industry or other significant barriers
severity of human-mediated risks. To explore
to orangutan movement.
species viability across this varied landscape
c. Habitat blocks: areas of roughly
it was first necessary to divide it into smaller
contiguous habitat within meta-
population units, using the maps and
population units.
information available. Each working group
began by breaking down the geographic d. Sub-blocks: specific sites of interest or
range of their taxon into a number of within habitat blocks, such as national
discrete, area-based population units, using parks.
the following hierarchy:

12 Orangutan Population and Habitat Viability Assessment

 c Fajar Saputra

Figure 3. Maping thread of Orangutan as put of workshop process

Once units were agreed upon, population was formed to consider challenges related
size estimates and trends for each unit to the management of small, fragmented
were discussed and estimated. For many populations and reintroduction. Groups
sites, groups were able to use Geographic worked to understand how each identified
Information System (GIS) models to estimate threat operates to reduce orangutan breeding
current population sizes, site carrying capacity, and survival rates, and also to understand the
and future rates of habitat loss. For other drivers and root causes of these threats. For
populations these estimates were based on each threat, potential mitigating strategies
survey data and the results of within-group were identified.
discussion. Details of these estimations are
Taxon-based working groups reformed on
provided in this report.
Day 3 to consider which threats are either
On Day 2, work began to clarify in detail the currently or potentially impacting each
direct threats to orangutans, the obstacles identified population, to what extent, and
to their effective conservation, and the over what time frame. Each was asked to
relationships between these factors. The key identify the: 1) main or most pressing threat
points of these initial discussions are illustrated for that taxon; 2) priority sites for action; and 3)
in Figure 3. New working groups were formed most important or most urgent conservation
around the main categories of threat: habitat strategies for those priority sites. Table 5
loss and degradation; hunting, poaching provides a summary of these recommended
and conflict; and fire. An additional group priorities.

Orangutan Population and Habitat Viability Assessment 13

GIS and PVA models
Preliminary GIS models were built for built to consider the specific circumstances
Sumatran and Bornean orangutans prior of individual populations and the expected
to the workshop and were refined during impact of these circumstances on future
the PHVA. For sites where sufficient data viability. Wherever possible, to provide
exist, modellers were able to relate forest transparency and consistency, GIS-derived
characteristics and patterns of human-use to estimates were used in the PVA models for
observed orangutan density. These general starting population size, site carry capacity,
rules were applied to areas for which survey and expected future rates of habitat loss to
data are absent or highly uncertain, to create orangutans. This was not always possible.
systematic estimates of range-wide orangutan At some smaller sites, survey data were
distribution and abundance. considered more reliable than GIS estimates
and in others it was not possible, in the time
Throughout the workshop and in the months available, to align the GIS spatial designations
following, population viability analysis (PVA) with the complex site boundaries defined by
models were developed by revising previous working groups. This is an area for future
PVA models based on information provided work.
by the working groups. The models were

Results
In total, the working groups identified 55 Sumatran orangutans living in eight wild
population and metapopulation units for PVA populations and a further 180 in two
analysis across Sumatra and Borneo, with reintroduced populations. Model results
population size estimates ranging from as few suggest that none of the eight extant wild
as 10 to as many as 10,450 individuals. As populations of Sumatran orangutans are
far as possible, threats to orangutans at each viable in the long term (500 years) under the
site were identified, the estimated impact projected rate and duration of habitat loss
quantified, and these effects included in the and harvest (removal of orangutans from
models. A breakdown of the main findings is the wild). Population fragmentation (e.g.,
provided below, by taxon. due to road construction) is likely to increase
the rate of decline and risk of extinction. The
Pongo abelii prognosis changes and viability becomes high
The designation of Sumatra orangutan (P. in models where habitat loss and harvest are
abelii) meta-populations follows Wich et al., halted immediately. The future of Sumatran
2016. Current population size and carrying orangutan populations will depend to a
capacity estimates are derived from GIS great extent upon the future rates of habitat
models, except in the case of the two release loss, fragmentation, and harvest, and how
sites (Bukit Tiga Puluh and Jantho Landscape). long these threats continue before they are
There are currently an estimated 14,290 reduced or eliminated.

14 Orangutan Population and Habitat Viability Assessment

Table 1. Summary of population viability analyses for Pongo abelii showing projected extinction risk at
100 and 500 years, for orangutans at each site, given the population and threat characteristics estimated
by participants at the 2016 PHVA workshop, with Initial N from Wich et al., 2016.

Extinction risk Extinction risk

Population Initial N Projected viability
at 100 years at 500 years

West Leuser 5,920 Poor 0.008 1

Sikulaping 260 Poor 0.15 1
East Leuser 5,780 Poor 0.004 1
Tripa Swamp 210 Very poor 1 1
Trumon-Singkil 1,270 Poor 0.000 1
Siranggas/Batu Ardan 90 Very poor 0.996 1
West Batang Toru 600 Moderate to poor 0.008 0.41
East Batang Toru 160 Poor 0.312 1
Bukit Tiga Puluh* 120 Good 0.000 0.016
Jantho landscape* 60 Good 0.000 0.000
TOTAL 14,4701 (SD ±2350)
* Released populations – projections assume continued releases for 10 years

Pongo pygmaeus morio

Participants estimated that there are ≈ 14,630 Kinabatangan, North Kinabatangan). Ulu
(SD ±1,330) P.p. morio in ~17 extant wild and kalumpang and Wahea-Lesan PF landscapes
released populations on Borneo. Data gaps represents a moderate-sized meta-population
and the difficulty of reconciling differences that may be vulnerable depending upon the
between GIS and site-based survey data did level of habitat loss and removals that impact
not allow for the development of individual it. There are 7 meta-populations of ~150-300
site-based models for this taxon in the time orangutans each; populations of this size may
available. However, the PVA results for Bornean be viable in the absence of threats but are
populations in general as well as those for vulnerable to loss of habitat and individuals.
P.p. pygmaeus, provide a useful guide to the Three meta-populations are small (under 50
range of viability of P.p. morio populations individuals) and subject to extinction risk even
under various conditions. A summary of these in the absence of threats.
general viability assessments is given in Table 2.
These viability assessments for P.p. morio
Based on the available information, there are populations are meant to serve as a guide
5 large meta-populations, mainly in protected only. As more information becomes available
areas in Sabah, that are likely to show long- on the size, available habitat, fragmentation
term viability as long as any loss of habitat and threats, the viability estimates for this
or orangutans remains low and/or short taxon can be revised.
term (Kutai NP, Tabin, Central Forest, Lower

1
This figure excludes an estimated 320 individuals living in various small forest fragments, which were not
included in the PVA analysis.

Orangutan Population and Habitat Viability Assessment 15

Table 2. Mean estimate of current population size, and likely trend, for 17 meta-populations of P.p. morio,
as collated by participants at the 2016 PHVA workshop (see Appendix III for details), with relative viability
estimates inferred from general PVA models. Viability decreases from green (high or good) to yellow
(moderate) to orange (poor). GIS estimates of population size, where available, are shown in parentheses.

Mean
Population Viability w/ no habi- Relative viability with Relative viability with
Meta-population est. of N
trend tat loss or removal habitat loss removals
(GIS)
30# Poor viability with- Poor; cannot withstand Poor; cannot with-
Beratus Landscape* Declining
out releases loss of K stand harvest
Sungai Wain Land- Poor viability with- Poor; cannot withstand Poor; cannot with-
20 Declining
scape* out releases loss of K stand harvest
Kutai NP-Bontang
Variable to High viability (if not Good viability if K re- Good viability if annu-
Landscape 1,700
declining fragmented) mains >500 al removal <1%

Belayan –Senyiur
Moderate viability (if Moderate if K remains Low viability if har-
Landscape 220 Declining
not fragmented) >200 vested

Wehea-Lesan PF Mostly Good viability (if not Good viability if K re- Good if annual re-
620
Landscape* declining fragmented) mains >500 moval <0.5%
Sangkulirang Land- 310 Moderate viability (if Moderate if K remains Moderate if annual
Declining
scape (775) not fragmented) >200 removal <0.5%
Tabin Range Land- 1,250 High viability (if not Good viability if K re- Good viability if annu-
Stable
scape (2,207) fragmented) mains >500 al removal <1%
Central Forest 5,320 Stable to High viability (if not Good viability if K re- Good viability if annu-
Range Landscape (4,765) declining fragmented) mains >500 al removal <1%
Lower Kinabatan-
1,500 Stable to High viability (if not Good viability if K re- Good viability if annu-
gan Range Land-
(1,082) declining fragmented) mains >500 al removal <1%
scape
North Kinabatan-
2,030 High viability (if not Good viability if K re- Good viability if annu-
gan Range Land- Stable
(979) fragmented) mains >500 al removal <1%
scape
Ulu Kalumpang 600 Good viability (if not Moderate if K remains Good if annual re-
Declining
Range Landscape (226) fragmented) >200 moval <0.5%
Crocker Range 180 Moderate viability (if Moderate if K remains May reduce viability
Stable
Landscape (106) not fragmented) >200 until N nears K
Lingkabau Land- 150 Moderate viability (if Moderate if K remains May reduce viability
Stable
scape (107) not fragmented) >200 until N nears K
Bonggaya Land- 190 Moderate viability (if Moderate if K remains May reduce viability
Stable
scape (104) not fragmented) >200 until N nears K
Ulu Tungud Land- 30 Poor viability with- Poor; cannot withstand Poor; cannot with-
Declining
scape (285) out releases loss of K stand harvest
Trus madi Land- 280 Moderate viability (if Moderate if K remains May reduce viability
Declining
scape (111) not fragmented) >200 until N nears K
Sepilok Landscape Moderate viability (if Moderate if K remains Moderate if annual
200 Stable
not fragmented) >200 removal <0.5%

*Release populations (and part of Wehea landscape in Kehje Sewen forest)

#Based on survey in 1/5 total area

16 Orangutan Population and Habitat Viability Assessment

Pongo pygmaeus pygmaeus
Total population size for P.p. pygmaeus was populations and their habitat will be critical
estimated to be ≈4,520 (SD ±790). Two large for the persistence of this taxon on Borneo.
P.p. pygmaeus meta-populations (Betung
Kerihun NP and Protection Forest, and None of the five remaining small fragments
Batang Ai-Lanjak-Entimau Landscape) have meets the viability criterion if they remain
high viability under the conditions modelled isolated, even if all threats are removed
and are projected to maintain about 3,600 and the three smallest fragments are not
orangutans combined. Provided habitat loss viable under current projected high rates
ceases as projected, the smaller population of habitat loss and/or harvest. The viability
at Danau Sentarum is projected to stabilize of small fragments can be greatly increased
at 680 orangutans. Protection of these large with the periodic release of translocated or
rehabilitated orangutans.

Table 3. Summary of population viability analyses for Pongo p. pygmaeus showing projected extinction
risk at 100 and 500 years, for orangutans at each site, given the population and threat characteristics
estimated by participants at the 2016 PHVA workshop.

Habitat Management Unit Estimated Projected Extinction risk at Extinct ion risk at
pop size viability 100 years 500 years

Betung Kerihun NP and 1,790 High 0.000 0.000

Protection Forest**
Batang Ai-Lanjak-Entimau 1,810 High 0.000 0.000
Landscape
Danau Sentarum NP and 680 Good 0.000 0.002
Corridor**
Klingkang Range NP and 80 Moderate to 0.001 0.272
Sintang Utara poor
Bungoh NP-Gunung Nyiut NR 90 Moderate to 0.000 0.191
and Penrisen PF poor
Pygmaeus fragmented North 30 Poor 1.000 1.000

Pygmaeus fragmented South 10 Poor 1.000 1.000

Ulu Sebuyau-Sedilu Landscape 30 Poor 1.000 1.000

TOTAL 4,520

Orangutan Population and Habitat Viability Assessment 17

 c FS Ngindang

Figure 4. Bornean Orangutan Pongo pygmaeus pygmaeus in Kapuas Hulu District, West Kalimantan.

Pongo pygmaeus wurmbii for each meta-population (excluding

It is estimated that there are 38,200 (SD one landscape believed to be devoid of

±2,760) individuals of P.p. wurmbii remaining orangutans).

in West and Central Kalimantan (with a few

The long-term viability of most P.p. wurmbii
individuals in South Kalimantan province).
meta-populations is moderate to poor
These occur in 10,170,196 ha of potentially
under current estimated rates of habitat
suitable habitat, although they are absent
loss and removals. While most have no risk
(except for four recently reintroduced
of extinction within 100 years, these meta-
populations) from habitat units totalling
populations are projected to decline by 60-
3,639,949 ha, resulting in an effective 2016
90%, reducing their size such that they may
range of 6,530,247 ha. Five regional units
become vulnerable to stochastic threats and
were defined comprising 17 forest landscapes
at risk. Only the three large meta-populations
or ‘meta-populations’.
(Tanjung Putting NP, Sabangau NP, Arabela

Data availability for P.p. wurmbii was Schwaner) remain large after 100 years given

intermediate between that available for P.p. projected threat levels.

pygmaeus and for P.p.morio, with general

Almost all populations (except for those
estimates available for population size and
few under 300 orangutans) may be viable if
threats. Table 4 provides the population
habitat loss and removal of orangutans were
estimates and relative viability assessment
halted.

18 Orangutan Population and Habitat Viability Assessment

Table 4. Current population estimates, trends and relative viability estimates over 100 years for 17 meta-populations
of P. p. wurmbii.

Relative viability
Est. N Population Relative viability w/ est. threats (for 100
Meta-population w/ no threats (for
trend yrs)
100 yrs)
Good viability
Kubu Raya 1,240 Declining ~86% decline; PE100=0 N100=111-235
Stable near K
Gunung Palung NP- Stable/ High viability
3,280 ~86% decline; PE100=0 N100=375-562
Sg Putri declining Stable near K
Good viability
Pematang Gadung 630 Declining ~86% decline; PE100=0 N100=68-107
Stable near K
~88% decline; PE100<0.026 N100=11-27; Moderate viability
Sungai Tengar 160 Declining
GD100=0.88-0.94 Stable near K
Poor viability;
>90% decline; PE100=0.3-0.86 N100=1-7;
Kendawangan-Jelai 50 Declining decline, some
GD100=0.68-0.81
extinction risk
Lamandau WR- Good viability
630 Stable ~86% decline; PE100=0 N100=73-106
Sukamara Stable near K
Good viability
Kotawaringin Lama 640 Declining ~86% decline; PE100=0 N100=60-119
Stable near K
High viability
Tanjung Puting NP 4,180 Stable ~61% decline; PE100=0 N100=1441-1800
Stable near K
Poor to moderate
~88% decline; PE100<0.06 N100=9-22;
Seruyan-Sampit 120 Declining viability; small
GD100=0.85-0.93
decline
High viability
Katingan 4,020 Declining ~86% decline; PE100=0 N100=472-663
Stable near K
High viability
Sabangau NP 6,080 Stable ~61% decline; PE100=0 N100=2272-2417
Stable near K
Rungan River High viability
2,260 Declining ~86% decline; PE100=0 N100=247-401
Landscape Stable near K
High viability
Kahayan-Kapuas 1,680 Declining ~86% decline; PE100=0 N100=151-331
Stable near K
Kapuas-Barito High viability
2,550 Declining ~86% decline; PE100=0 N100=281-434
(Mawas) Stable near K
~87% decline; PE100=0-0.008 N100=18-41; Moderate viability
Barito Timur 230 Declining
GD100=0.92-0.96 Stable near K

Siawan-Belida 0 -- Not assessed Not assessed

High viability
Arabela Schwaner 10,450 Stable ~59% decline; PE100=0 N100=3479-5133
Stable near K

TOTAL 38,200

Orangutan Population and Habitat Viability Assessment 19

Additional Analyses
In addition to questions about the viability of accumulation). A minimum population of
individual populations, workshop participants 200 orangutans is needed for both species to
posed additional questions for the PVA models, retain 90% GD for 500 years, and at least 500
the answers to which can be summarised as orangutans are needed to stabilize population
follows: size and avoid decline. All of these thresholds
are higher if the initial animals are related or
What is the projected impact on orangutans of subject to increased threats.
the construction of roads through orangutan
habitat (e.g., in West and East Leuser, in West What is the smallest current population that
and East Batang Toru)? could meet the MVP standard if allowed
space to grow larger (e.g., reintroductions
PVA results for road fragmentation scenarios into a new area, additional habitat added to
in this report are conservative, as they do not an existing area)?
consider potential impacts of roads such as
additional mortality or increased accessibility. Populations of at least 50 orangutans are
Fragmentation alone did not greatly impact able to meet the MVP standard if they have
viability for large populations with no threat sufficient space to grow, provided they are not
of habitat loss or removals. In the presence under threat of habitat loss, fragmentation
of such threats, fragmentation due to roads or harvest. These results are based on the
hastens decline and time to extinction and current PVA model, which incorporates
in most scenarios led to eventual extinction density-dependent reproduction and thus
under current projected threats. allows populations to grow at a faster rate at
low density.
What is the smallest population size that can
meet the agreed standards for a Minimum What level of periodic supplementation
Viable Population (MVP)? How does this size would be needed to maintain the viability of
change with different conditions or threat small populations below the MVP?
levels?
The supplementation rate required will
For this purpose, workshop participants depend upon the population size and threat
defined a viable population as one with < 1% levels. PVA results suggest that the addition of
probability of extinction in 100 years and < one young adult female every ~35 years can
10% probability of extinction in 500 years. provide viability to a population of 50, while a
Given this definition, the MVP fis 150 for population of 20 may need supplementation
Sumatran orangutans and 100 for Bornean with one adult female every 13 years. Very
orangutans. However, populations of 100- small fragments may be at risk of losing their
150 demonstrate a slow declining trend only breeding male and may require addition
and reduced gene diversity (i.e., inbreeding of an adult male in some cases.

20 Orangutan Population and Habitat Viability Assessment

What is the viability of populations established of releases into a large area of unoccupied
using a specified reintroduction scheme? habitat. Releases were of sub-adult and
young adults and were female biased. The
Release strategies may vary the age, sex and
combination of a young, female-biased
number of orangutans released as well as the
population at low density promotes faster
length and schedule of release. A thorough
growth and overall population viability.
assessment of reintroduction schemes is
beyond the scope of this PVA. However, a Full details of the PVA analyses are provided
specific scheme was modelled that involved in this report.
four consecutive years of a large number

Recommendations and Next Steps

On the basis of workshop deliberations, participants identified key threats, priority sites and
priority strategies for each taxon, summarized below in Table 5.

Table 5. Summary of recommended priorities for orangutan conservation

Main threats to
Taxon Priority populations Recommended priority strategies
the taxon

Habitat conversion • Moratorium on palm oil de-

& fragmentation, velopment
All orangutan popu- • Closure of illegal roads
Pongo especially oil palm
lations, both wild and
abelii expansion, non- • Law enforcement
reintroduced.
road infrastructure, • Better spatial planning
and roads. • Better forest management

Danum Valley, USM, • Moratorium on palm oil de-

Pongo p. Habitat conversion Forest Foundation FC; velopment
for industrial agri- Wehea Landscape
morio • Law enforcement
culture (incl. Kehje Sewen);
Kutai NP. • Better spatial planning

Pongo p. Habitat conversion Betung Kerihun NP • Moratorium: no new permits,

for industrial agri- and BALE landscape & no clearing forest within con-
pygmaeus culture Danau Sentarum NP. cessions.

• Law enforcement
Arabela Schwan-
er; Tanjung Puting • Policy change: moratorium on
Pongo p. Fires and habitat peat land and natural forest
NP; Sabangau NP;
conversion for in- conversion to other purposes.
wurmbii Mawas; Rungan River;
dustrial agriculture
Gn Palung NP-Sungai • Harmonise of regulations
Putri (MoEF, MoEMR, MoAgr,
MoASP2)

Ministry of Environment and Forestry (MoEF), Ministry of Energy and Mineral Resources (MoEMR, Ministry of Agriculture (MoAgr),
2

Ministry of Agrarian and Spatial Planning (MoASP)

Orangutan Population and Habitat Viability Assessment 21

The next steps in pursuing these identified • Responding to the recent change
priorities are as follows: in conservation status of Bornean
orangutans, released by the IUCN in
• Developing a new National Orangutan
2016; and
Strategy and Action Plan for 2017-2027,
including key elements such as law • Using the orangutan as a benchmark
enforcement; for the monitoring and evaluation of
25 species conservation priorities in
• Revising island, provincial, and district
Indonesia.
level spatial planning to mainstream
orangutan conservation and synchronize
policy and regulation among ministries;

c Fajar Saputra

Figure 5. Group Discussion Process

22 Orangutan Population and Habitat Viability Assessment

 Steering Committee Notes

Orangutan (Pongo spp) is currently only found The Ministry of Environment and Forestry
on the islands of Sumatra and Kalimantan. (Kementerian Lingkungan Hidup dan
This Indonesian iconic species is the only Kehutanan) has established a steering
great ape that lives in Asia and is classified as committee to assist in the implementation
a critically endangered species by IUCN 2016, of the 2016 Orangutan PHVA. The steering
and is a species protected by Indonesian law. committee is established through a Decree of
Orangutan threat is caused by several factors the Director General of Natural Resources and
such as habitat depletion due to uncontrolled Ecosystem Conservation (Surat Keputusan
forest conversions, poaching and trafficking Direktur Jenderal Koservasi Sumber Daya
of orangutans. Uncontrolled resource Alam dan Ekosistem/KSDAE) No. SK.229 /
utilization for economic development, as well KSDAE-Set / 2015 with the aim of providing
as other illegal activities, has resulted in the direction in coordinating data collection
destruction and depletion of forest areas as and updating of data on the assessment of
orangutan habitats that ultimately have an the sustainability of Indonesian orangutan
impact on the declining number of orangutan population and habitat from species
populations. To find out the current condition conservation activists, providing guidance
of orangutans and to project future conditions, in the assessment and determination of
Orangutan Population and Habitat Viability population counting/census methods used
Assessment (PHVA) has been conducted. The in the assessment of population sustainability
study of habitat and orangutan population is and Orangutan habitat in accordance with
of great importance to all parties, especially the scientific principles that can be accounted
those involved in saving efforts of this species, for. The team is also mandated to evaluate the
in relation to the end of the Indonesian Indonesian Orangutan Conservation Strategy
Orangutan Indonesia Conservation Strategy and Action Plan (Strategi dan Rencana Aksi
c Muhammad Khoir

and Action Plan 2007-2017. Konservasi/SRAK) 2007-2017, based on

Orangutan Population and Habitat Viability Assessment 23

the assessment of the sustainability of the have been trained by FORINA and /
population and its habitat and the periodic or the Directorate General of Natural
evaluations that have been conducted, Resources and Ecosystem Conservation
and direct the drafting of the Indonesian (KSDAE), Ministry of Environment and
Orangutan SRAK 2017-2027. The team Forestry. This training is intended for the
consists of Indonesian Academy of Sciences, equation of methods. The method used
Research Development and Innovation is systematic design for line transect
Agency of the Ministry of Environment and with randomly sampling. To consolidate
Forestry, Indonesian Institute of Sciences, the information from the parties, prior
University of Indonesia, National University, to the implementation of PHVA has also
Indonesian Orangutan Forum (FORINA) and conducted Pre-PHVA activity in each
Conservation organizations (The Nature region (For more detail information find
Conservancy, Wildlife Conservation Society, in Appendix I). Data input for viability
and Kehati Foundation). analysis on 2016 Orangutan PHVA
is more comprehensive compared to
After a long process, the executing previous Orang PHVA. This is possible
team, editing team and the Conservation because data are collected from more
Breeding Species Group (CBSG) team of location points, and derive from long-
the International Union for Conservation of term research observations involving
Nature (IUCN) succeeded in preparing the more stakeholders.
2016 Orangutan PHVA Report. Based on the
b. The forecasts of density of Sumatran
received 2016 PHVA Orangutan report, the
orangutans and Borneo has decreased
Steering Committee notes some important
compared to previous forecasts in
things, namely:
PHVA. This illustrates that threats to the
a. The survey data that became information sustainability of orangutans and habitats
in 2016 Orangutan PHVA had coverage are increasing, due to increased forest
area twice as wide as compared to conversions, and the high frequency
previous orangutan PHVA (88,981 km2 of orangutan rescue and confiscation
vs 181,694,62 km2). The expansion activities. Therefore, it is necessary to
area of ​​this survey occurred in Sumatra safeguard the Conservation Area and the
and in Kalimantan, horizontally and application of BMP (Better Management
vertically (reaching an altitude of 1,500 Practices) in the concession. In addition,
meters above sea level). Surveys are orangutan conservation efforts should
conducted in conservation areas and be comprehensive by integrating
outside Conservation Areas (especially the ecological, social and economic
in Kalimantan). The distribution of interests (conservation by design).
orangutans in Kalimantan is almost c. The high estimated population of
80% outside the Conservation Area, Sumatran orangutans (Pongo abelii)
including in plantation concessions, compared to previous forecasts in
forestry concessions, and mining Orangutan PHVA does not mean an
concessions. Prior to conducting increase in population in the previous
the survey, most of the surveyors

24 Orangutan Population and Habitat Viability Assessment

 orangutan PHVA survey area, but is variation Genetic. If this is used as a
caused by a wider coverage of survey reference, then quite a lot of meta
areas (horizontal and vertical) that populations which are at the low level
had not previously been done. Thus it of viability in three sub-species of
can change the previous assumptions Kalimantan orangutans, mainly due
and estimates. The results of the to the large number of fragmented
most actual survey were: (1) previous metapopulasi. Therefore, it is necessary
assumptions of orangutans are only to add orangutan habitat in the form of
found at altitudes below 800 m-above Conservation Area and the formation
sea level, but in the most actual of corridors for fragmented habitats.
surveys orangutans are also found in
e. The two sub-species of Borneo
higher forests, so that former forest
orangutans, Pongo pygmeaus
habitats which were not categorized as
pygmaeus and Pongo pygmaeus
orangutan habitat, currently included
morio, are species that can be found
into the orangutan habitat category; (2)
on Borneo island of Indonesia and
the most recent survey and research find
Malaysia. Although Pongo pygmaeus
that orangutans can survive in logged-
morio is in Indonesia and Malaysia, it is
over forest areas that are managed
located in a different meta population.
sustainably; (3) the most actual surveys
In 2016 Orangutan PHVA it was
also found the orangutan population in
identified that several meta populations
the area west of Lake Toba. It should
exist in Indonesia and Malaysia border
also be noted that the threat to the
areas i.e (1) Betung Kerihun National
sustainability of Sumatran orangutan
Park (Indonesia) and Batang Ai-
habitat and population is increasing.
Lanjak-Entimau (Malaysia) landscape,
d. The forecast of the Kalimantan (2) Klingkang Range National Park
orangutan population in the 2016 (Malaysia) and forests in North Sintang
orangutan PHVA declines from the (Indonesia), (3) Bungoh National Park
previous forecast on PHVA. If the (Malaysia) and Penrisen protected forest
report is further scrutinized, the (Indonesia). Betung Kerihun National
steering team finds some interesting Park and Batang Ai-Lanjak-Entimau
information, among others: (1) The are priority areas that have the largest
2016 population forecast is based on population of Pongo pygmeus pygmeus
information derived from the broader sub-species with high population
survey coverage, while earlier forecasts viability projection. Meanwhile,
are based on a limited survey; (2) Based two other meta-populations, have
on the results of viability analysis, the medium to low viability projections.
minimum population to maintain To sustain populations in these three
viability population in Kalimantan is in meta-populations, the steering team
200 orangutans for <1% probability encouraged the need for synergicity
of extinction in 100 years and <10% of conservation plans and actions
probability of extinction in 500 years, undertaken by Indonesia and Malaysia.
and 500 orangutans to maintain

Orangutan Population and Habitat Viability Assessment 25

Based on important notes from the 2016 3. Based on the 2016 PHVA Orangutan
PHVA Orangutan Report, the Steering team Report and the results of the review,
recommend several things to follow up on: indicate that the population of the
Kalimantan orangutan is declining, but
1. The result of PHVA Orangutan 2016 can this decline has not been at a pace that
be used as a reference in the preparation causes the need to change the status of
of SRAK Orangutan Indonesia 2017-2027 the IUCN conservation. Quite a lot of meta
together with the SRAK evaluation that populations are at a fairly high level of
has been conducted periodically, so that viability in three sub-species of the Borneo
the SRAK Orangutan 2017-2027 which orangutan, although many of the meta
is compiled will be more comprehensive populations are fragmented.
and have specific, measurable and rational
4. This review suggests that the decline in
targets within the stipulated evaluation
the conservation status of the Borneo
period.
Orangutan undertaken by IUCN primate
2. After the formation of SRAK Orangutan experts in 2016, from endangered species
Indonesia 2017-2027, because of the status to critically endangered species, is
importance of managing the orangutan inappropriate with current circumstances
population in the trans-boundary areas and needs to be revised.
of Indonesia and Malaysia, it is necessary
to synchronize the SRAK between the
two countries, in the form of information
sharing in order to have integrated
collaborative action.

26 Orangutan Population and Habitat Viability Assessment

 Threats To The Conservation
Of Orangutans

Threats to orangutan viability and conservation across the range were discussed by
workshop participants, and the outputs are illustrated in Figure 2. To assist discussions, the
threats described were grouped as follows: 1) Habitat loss and degradation; 2) Hunting,
illegal capture and conflict; and 3) Fire. Working groups were formed around each of these
categories. For the threats assigned, each group discussed and developed: a description
of the threat or threats; their regional specificity and primary causes or drivers; specifically,
how the threats affect orangutans; what is known about the threats, what is assumed,
and what are the key data gaps in regard to achieving effective conservation; and what are
the options for mitigation. A fourth group was formed to consider issues related to small
population size, orangutan reintroduction projects, and disease. This group followed a
different format than that of other groups as its deliberations were designed to be informed
by population viability analysis models.

Habitat loss and degradation

Encroachment of forests by local communities reduces
In both Sumatra and Borneo, a lack of habitat for orangutans (by 100% in the
enforcement allows forest encroachment by area cleared), and may increase mortality
local communities. Two types of effect were through a small increase in human-
described: orangutan conflict. This activity may lead
to more extensive small-scale agriculture
1. Small scale agriculture (see below).
Limited and temporary but illegal clearance

Orangutan Population and Habitat Viability Assessment 27

2. Extensive small scale agriculture 3. Infrastructure

Extensive and long-term or permanent In both Sumatra and Borneo, legal and
illegal clearance of forest by local illegal forest clearance for infrastructure,
communities leads to orangutan including geothermal, electricity,
population fragmentation in addition to hydroelectric, and military infrastructure
habitat loss and increased mortality from occurs. This may be initiated by government
conflict events. or the private sector as part of development
programmes and is driven by poor
Forest conversion
governance, inappropriate government
1. Industrial agriculture policy, lack of law enforcement, poor
In both Sumatra and Borneo, market spatial planning, and the priorities of local
demand, speculation, corruption, and elite. In areas where it occurs 100% of
the potential for government income and habitat is lost to orangutans and incidences
employment are drivers of large-scale forest of conflict increase.
clearance for palm oil, rubber and other
Road construction
industrial-scale crops. Benefits are mostly
In both Sumatra and Borneo, road construction
accrued by big corporations and local elites.
fragments orangutan populations, increases
It results in direct habitat loss (in which
forest access and leads to encroachment
100% of the area is lost to orangutans),
and settlement expansion. Where habitat
habitat fragmentation, greater access and,
loss occurs it reduces carrying capacity by
as a result, more incidences of conflict and
100%. Drivers of this are government policy,
associated mortality. In peat areas, laying
poor spatial planning, corruption, economic
canals removes all available habitat for
development, the needs of the local elite,
orangutans in the immediate area reduces
and the drive for better human access to
the carrying capacity of surrounding areas.
areas, particularly where there are industrial
2. Mining concessions and for tourism.

This occurs in Sumatra and in Borneo

Settlement
outside Sabah. Forest clearance for mining
In Sumatra, and in Borneo outside Sabah and
is mostly conducted by big corporations
Sarawak, legal and illegal forest clearance
but also includes illegal mining by local
for housing and agriculture occur to fulfil
communities. Mining increases forest
the demands of expanding local human
access and encroachment of settlements,
populations, which include relocated disaster
which leads to habitat loss, increasing
victims and those moved as a result of the
fragmentation and a small increase in
government’s transmigration program.
mortality through human-orangutan
Impacts on orangutans include reduced
conflict. Drivers for this are economic gain
habitat and increased conflict leading to
and market demand.
mortality. Drivers of these impacts are poor
governance, inappropriate government policy,

28 Orangutan Population and Habitat Viability Assessment

 Mining Conversion for Oil Uncontrolled
Palm infrastructure
development

Lack of law Illegal logging

enforcement Loss of carrying
Road development
capacity (loss,
Agriculture
fragmentation or
Encroachment
degradation of habitat)

c Misdi
concessions

Canalisation
Lack of knowledge Small
ENSO or awareness pop
n

size
Orangutan Lack of effective
Increased forest
Changed hydrology (in access
Forest fires
peat forests) viability action

Lack of resources
Climate change
Inbreeding

Direct loss of
Translocation Lack of law
orangutans (more Human-orangutan
Disease outbreak conflict enforcement
deaths, extractions, or
fewer births)
Tourism Hunting & poaching

Figure 6. Current and potential threats to orangutans24

identified by participants at the 2016 PHVA workshop

Orangutan Population and Habitat Viability Assessment 29

human conflict and natural disasters occurring impact logging method” can significantly
in other areas, and poor law enforcement. reduce carrying capacity for orangutans and
increase human-orangutan conflict. The
Logging
incidence of high impact logging is increased
Logging can be carried out in a variety of by poor controls and weak forest governance.
ways and these can differ in their impact on
orangutans. Timber plantation
In Sumatra and in Borneo outside Sabah and
Illegal logging
Sarawak, forest clearance for industrial timber
In both Sumatra and Borneo, illegal timber crops, mostly carried out by big corporations
extraction within forest cover can temporarily and local elites, increases forest fragmentation
reduce carrying capacity for orangutans and and access, resulting in the loss of these
increase mortality due to orangutan–human areas to orangutans and increasing mortality
conflict. Drivers or causes are considered considerably. Drivers are market demand,
to be poor governance and inappropriate speculation, corruption, and the potential for
government policy, lack of law enforcement, government income and employment.
local timber demand, and the opportunities
created through greater access for agriculture. Absence of forest management units
In Sumatra and in Borneo (excluding Aceh,
Low impact logging
Central Kalimantan, Sabah and Sarawak),
In Borneo, logging activity that follows a insufficient budget resources and coordination
“reduced-impact logging method” either among related parties result in the absence
fully or partially, does not reduce the carrying of forest management units (KPH) to enforce
capacity of the affected habitat. regulation and protection, which leads to
open access to forest resources and results in
High impact logging
loss, fragmentation, further settlement and
Also in both Sumatra and Borneo, logging
degradation.
activity that does not follow a “reduced-

Hunting, Illegal Capture And Conflict

This category included those threats that are individuals are re-released there could be
expected to result directly in orangutan deaths disease implications. In addition to the
or extraction (other than fire, which was dealt conservation implications there are negative
with separately). welfare consequences for the animals
taken. This activity is driven by lack of law
Poaching (illegal capture)
enforcement, demand from the pet trade, lack
In both Sumatra and Borneo, poaching of awareness of the law and misperceptions
or illegally capturing orangutans for about orangutans, low income and the
domestication or trade could reduce the resulting incentive of potential economic
viability of wild populations directly. Where gain, and opportunities created by increased
forest access.

30 Orangutan Population and Habitat Viability Assessment

Hunting 1. Crop raiding
Orangutans are killed as a source of food for Orangutans that raid crops may be killed
subsistence; often this killing is opportunistic or wounded either as retribution for losses
but not always. This occurs throughout the or defensively, out of fear.
range but is more prevalent in Borneo. This
additional mortality may increase the risk of 2. Opportunistic hunting
local extinctions. It is thought that hunting Orangutans encountered opportunistically
played a role in some of the areas where in the forests by hunters may be killed for
orangutans do not occur anymore. Also it may food or poached for trade.
have reduced overall density in many areas.
Agriculture expansion, habitat loss, and
Causes are low income and the opportunities
increased forest access increase the rate
created by increased forest access due to
of human-orangutan encounters. Lack
agricultural expansion and habitat alteration,
of knowledge of the protected status
hunting traditions in local culture and lack of
of orangutans, lack of awareness of the
Law enforcement.
nature of orangutans, fear of economic
Human-orangutan conflict loss, and poor law enforcement may all
In cases of human-orangutan conflict, both contribute to negative outcomes from
parties may be impacted negatively and these interactions.
orangutans are often killed. Two main areas
In Sumatra there are more instances of
where conflict occurs were identified as:
small holder-based conflict. In Borneo the
conflict is more often related to activities
by timber and oil palm companies.

Fire

Impact on orangutan viability Population density in remaining habitat

There are a number of potential mechanisms increased, which may trigger conflict
through which fire events can impact between orangutans, increasing mortality
orangutan population viability, such as direct and facilitating disease outbreak. These
killing, destroying and fragmenting the conditions can also lead to reduced
habitat, and reducing the carrying capacity reproduction. The increased isolation of
(i.e., reduction of population size). remaining fragments may in the long-term
increase the likelihood of inbreeding.
1. Habitat loss and fragmentation
2. Direct mortality and injury
Loss and fragmentation of habitat reduces
the ability of orangutans to travel between Fire can kill orangutans directly, or indirectly
trees and make nests. Access to food as a result of haze. Others can be left with
is reduced and vulnerability increases. debilitating injuries.

Orangutan Population and Habitat Viability Assessment 31

3. Regional specificity Causes

Peat swamp forest is particularly vulnerable 1. Climate Change

to forest fires. The dried-out peat ignites Forest fires occur during dry season and
easily and also burns underground, worsen during El Niño events. Climate
travelling unseen beneath the surface to change is expected to increase the
break out in unexpected locations. Fire frequency and severity.
susceptibility in these areas is exacerbated
by drainage and irrigation canals that alter 2. Land use conversion
the hydrology. Lowland Dipterocarp and Uncontrolled fires set as part of land
heath forest are also at risk. All Kalimantan clearing strategies have increased the
is dry, especially in the centre. incidence of large fires. In some peat land
areas, canalization due to drainage of the
land has also affected the water table and
make the peat land more vulnerable to fire.

Small Population Size, Reintroduction And Disease

The threats described above lead directly or Population fragments

indirectly to orangutan population declines. A number of the orangutan populations
As populations decline to small numbers considered at the 2016 PHVA workshop have
their dynamics are increasingly influenced by been driven to small numbers as a result of
chance or “stochastic” effects. These effects habitat loss, fragmentation and extraction,
are typically characterised as: environmental resulting from the threatening process
(random, unpredictable variation in factors described in this report. Understanding
such as temperature or food supply); which population fragments are likely to be
demographic (chance-driven fluctuations in experiencing the negative effects of small
birth or death rates or sex ratio); catastrophic size can be helpful in considering where
(extreme natural or human-caused events supportive management might be needed.
such as fire or environmental disasters); and
genetic (the negative effects of inbreeding Reintroduction
accumulation and gene diversity loss on The reintroduction of orangutans into areas
population fitness and adaptive potential) where they do not currently exist involves an
(Shaffer 1987). Where populations remain initial phase where the population is small in
small, these effects can be sufficient to drive size and as a result disproportionately impacted
populations to extinction even after the by random events. Planning reintroduction
threats that caused the initial declines have programs can benefit from an understanding
been removed (Gilpin and Soulé 1986). These of what combinations of founder number,
effects are relevant to orangutans in the age, sex ratio, and ongoing supplementation
following contexts. rate might be expected to lead to successful
establishment of orangutans at a given site.

32 Orangutan Population and Habitat Viability Assessment

 Disease populations are small and isolated, where
Disease may contribute to fluctuating size there is overcrowding (e.g. after fires), where
in large populations but is rarely cited as a inbreeding has accumulated and general
primary agent of extinction at the species fitness levels are already compromised, or
level (Callum, 2012; McPhee & Greenwood, where regular disturbance from human-
2012). Though not expected to be a risk at mediated activity (e.g. tourism, orangutan
the species level, for orangutans, disease reintroduction or translocation) may increases
may pose a risk at the individual population exposure to potential disease agents.
level, and this risk may be increased where

Potential mitigation strategies

For the threats described, working groups strategies outlined in Table 6 below.
identified a list of potential mitigating

Table 6. Threats to orangutans and associated threat mitigation strategies as identified

by participants at the 2016 PHVA workshop.

Encroachment Conversion Logging

Road construction

Timber plantation

Illegal capture &v

Small population
Absence of FMU
Threats
Infrastructure

Illegal lgging

Disease risks
High impact
Small- scale

Low impact

Human-OU
Small-scale

Settlement
agriculture

agriculture

agriculture

Potential mitigating
extensive

Industrial

hunting
logging

logging

conflict
Mining

strategies

risks
Fire
Enforce laws X X X X X X X X
Improve law enforcement
capacity within local and central X X
government
Prosecute law-breaking
X X X
companies
Close illegal roads X
Prevent new and re-locate
X
existing, illegal settlements
Strengthen monitoring, patrolling
and enforcement capacity, and X X X
informant networks
Operate patrols (Satgas PMH) in
X X
concessions
Strengthen regulation,
participation and reward and
punishment in relation to
protecting orangutans and
biodiversity from fires
Implement SCS SVLK timber
X X X
legality verification
Educate and train law enforcers
on the rules and regulations
X
around forestry, biodiversity and
the environment

Orangutan Population and Habitat Viability Assessment 33

 Encroachment Conversion Logging

Road construction

Timber plantation

Illegal capture &v

Small population
Absence of FMU
Threats

Infrastructure

Illegal lgging

Disease risks
High impact
Small- scale

Low impact

Human-OU
Small-scale

Settlement
agriculture

agriculture

agriculture
Potential mitigating

extensive

Industrial

hunting
logging

logging

conflict
Mining
strategies

risks
Fire
Impose a moratorium on Izin
Pinjam Pakai Kawasan (legal
X
land-use permit) for mining in
orangutan habitat
Impose a moratorium on
agriculture expansion in X
orangutan habitat
Impose a moratorium on new
permits and on clearing forest X X X
within concessions
Educate, socialise and raise
awareness – promote a sense of
X X X X X X X X X
ownership & responsibility for
orangutans
Promote alternative economic
X X X X X X X
livelihoods
Evaluate cost-benefit of long-term
palm oil and timber plantations
X X
(with transparent, publicly
available results)
Promote supply chain
X X
transparency
Encourage and incentivise sound
spatial planning (provincial
or district/city) and make the
X
planning process and relevant
information publicly accessible
and transparent
Improve spatial planning for
orangutans (to include protection
of critical conservation areas,
reduced fragmentation from X X X X X X X
roads, effective corridors,
settlements with reduced chance
of human-orangutan conflict)
Harmonise needs of land set-aside
for conservation with plantation
X
concessions & land resource (BPN)
regulations
Identify and manage HCV areas
X X X
effectively
Build corridors to connect
HCV areas within concessions
X X X
to neighbouring viable forest
patches
Implement Better Management
X X X X X
Practices (BMP)

34 Orangutan Population and Habitat Viability Assessment

 Encroachment Conversion Logging

Road construction

Timber plantation

Illegal capture &v

Small population
Absence of FMU
Threats

Infrastructure

Illegal lgging

Disease risks
High impact
Small- scale

Low impact

Human-OU
Small-scale

Settlement
agriculture

agriculture

agriculture
Potential mitigating

extensive

Industrial

hunting
logging

logging

conflict
Mining
strategies

risks
Fire
Implement elevated roads to
X
minimise impact
Encourage effective replanting
policies, reclamation and X X X X X X
reforestation
Encourage local community
planting schemes on their lands,
X
for community/personal use (e.g.
house refurbishment)
Strengthen multi-stakeholder
partnerships around key issues
X X X X
such as law enforcement and fire
(local, national, international)
Equip companies with the
knowledge to reduce human- X
orangutan conflict
Build community capacity to
respond to and mitigate human- X
orangutan conflict
Set up conflict response units X
Encourage effective FMUs to
support orangutan habitat
in every region (population X
monitoring, conflict response,
ecosystem restoration etc)
Educate and train local
community representatives and
concession holders (e.g. mining,
plantation and logging personnel)
on the importance of a) early- X
warning systems and Standard
Operating Procedures (SOPs) for
alerting fire fighters, and b) fire
management
Awareness campaigns for
preventing fire (warning signs, X
etc)
Restore soil, plant, and hydrology
(through canal blocking and X
habitat restoration, etc)
Strengthen infrastructure and
ensure the presence of a skilled
fire management unit in every
X
site or village community (wells,
personal safety provisions, SOPs
for fire-fighting, etc)

Orangutan Population and Habitat Viability Assessment 35

 Encroachment Conversion Logging

Road construction

Timber plantation

Illegal capture &v

Small population
Absence of FMU
Threats

Infrastructure

Illegal lgging

Disease risks
High impact
Small- scale

Low impact

Human-OU
Small-scale

Settlement
agriculture

agriculture

agriculture
Potential mitigating

extensive

Industrial

hunting
logging

logging

conflict
Mining
strategies

risks
Fire
Strengthen networking among
stakeholders (regional, national,
X
and international forest and land
fire agencies)
Increase research on fire risk
management and its impacts
X
on orangutan habitats and
populations
Strict tourism regulation
X

Implement disease risk assessment

and management in rehabilitation X
centres
Raise awareness about disease
X
risks in target audiences
Include disease surveillance in
post release monitoring and X
evaluation
Develop a disease communication
strategy (OVAG) X

36 Orangutan Population and Habitat Viability Assessment

 Working group

Pongo abelii surveys found no evidence of their continuing

survival south of the Batang Toru forest block
Working group members:
area. There are only approximately 14,470
Dedi Yansyah (FORA), Desi Satya Chandradewi (SD ±2350) wild orangutans of this taxon left,
(Ministry of Environment and Forestry), inaddition to two reintroduction populations
Ermayanti (FORINA), Fitri Noor Chasanatun that at present number <150 individuals each
(BB BKSDA North Sumatera), Hadi Sofyan (Wich et al., 2016). The taxon is categorized
(BKSDA Aceh), Ian Singleton (PanEco-Sumatra as Critically Endangered by IUCN (Singleton et
Orangutan Conservation Programme), Irham al., 2016).
Fauzi (FORINA), Julius Siregar (Frankfurt
The core populations are centered in Leuser
Zoological Society), Khairul Azmi (FOKUS),
Ecosystem, including Leuser National Park,
Kuswandono (Gunung Leuser National
Tripa Swamp, and Trumon-Singkil Swamp,
Park), Matthew G. Nowak (PanEco- Sumatra
as well as Siranggas/ Batu Ardan Forest and
Orangutan Conservation Programme),
Sikulaping in Pakpak Bharat, North Sumatra.
Panut Hadisiswoyo (FOKUS), Serge A. Wich
The other highly populated area is in Batang
(Liverpool John Moores University)
Toru forest block in North Sumatra. The
Introduction Batang Toru population, estimated to be <800
Pongo abelii is endemic to Sumatra, individuals (Wich et al. 2016), is completely
Indonesia. It is restricted to the north of the disjunct from the northern Sumatran
island. It was once far more widespread, orangutan populations and is now known to
occurring as far south as Jambi and West be genetically unique (Nater et al., 2015). In
Sumatra provinces until at least the mid- addition to the wild populations, two entirely
1800s (see Rijksen, 1978; Rijksen & Meijaard, new Sumatran orangutan populations are
1999). There were in fact reports of Sumatran gradually being established through the
orangutans in some parts of West Sumatra reintroduction of confiscated illegal pets: one
c Arif Rifqi

Province as recently as the 1960s, but many in and around Bukit Tigapuluh National Park

Orangutan Population and Habitat Viability Assessment 37

Figure 7. Map of Sumatra showing meta-population delineations for P. abelii.

38 Orangutan Population and Habitat Viability Assessment

(Jambi and Riau provinces), and one in and 2011). Habitat conversion is a direct threat to
around the Jantho Pine Forest Nature Reserve orangutan mortality, in some cases orangutans
in the far north of Aceh. All populations, may be directly killed during the process of
including the two reintroduced ones, are conversion, but often orangutans die due to
shown in Figure 3. All current populations, lack of suitable habitat/resources, starvation,
both wild and reintroduced, are identified as and malnutrition. Surviving infants are taken
a priority for P. abelii conservation, because for illegal wildlife trade. All of P. abelii habitat
the associated habitats have high potential in Aceh, both East and West Leuser, Tripa
to support viable populations and require Swamp, and Trumon-Singkil Swamp face the
intense protection. problems associated with palm oil plantation
expansion. Road construction also threatens
Habitat conversion and fragmentation, due to sustainability of this taxon in West Leuser, East
agricultural expansion (e.g., oil palm, rubber, Leuser and Trumon-Singkil swamp. Non-road
etc.), non-road infrastructure development infrastructure (e.g., geothermal, hydroelectric,
(e.g., geothermal and hydroelectric plants), and mining operations) threaten core areas in
and road development, remain the major East and West Leuser and West Batang Toru.
threats to orangutan survival over most of The main strategies proposed for tackling and
the range occupied by P. abelii (Wich et al., mitigating these threats are listed in Table 7.

Table 7. Summary of the main threats and recommended mitigation strategies, for P. abelii.

Threats Mitigation Strategy

Better spatial planning

Agricultural conversion Implementation of a moratorium on palm oil development

• Oil palm Improved forest management
• Rubber Patrol and law enforcement operations
Alternative livelihood promotion
Better spatial planning
Closure of illegal roads
Road construction Improved forest management
Patrol and law enforcement operations
Alternative livelihood promotion
Non-road Infrastruc- Better spatial planning
ture
Improved forest management
• Geothermal
• Hydroelectric
Stakeholder engagement
• Mining
Patrol and law enforcement operations
Improved forest management
Agriculture
Stakeholder engagement
encroachment
Social forestry in target areas
Alternative livelihood promotion

Orangutan Population and Habitat Viability Assessment 39

Pongo pygmaeus morio FC, were also identified as priority populations
in Sabah. Meanwhile in Kalimantan, most
Working group members:
populations of P.p. morio are found outside
Aldrianto Priadjati (FORINA), Donna Simon
protected areas in forests that are earmarked
(WWF Sabah), Eko Prasetyo (Borneo
for conversion to other land uses. There are 6
Orangutan Survival Foundation), Fajar
landscapes in Kalimantan recognized as major
Saputra (FORINA), Hardi Baktiantoro (Centre
habitat with a total population are 2,900 (SD
for Orangutan Protection), Purwo Kuncoro
±750) orangutans. The core population of
(Kutai Orangutan Project), Anne Russon
P.p. morio in Kalimantan is centered in Kutai
(Kutai Orangutan Project), Rizal Buchari (The
National Park-Bontang landscape, which
Nature Conservancy), Sendi Yusandi (Ministry
is estimated to support more than 1,000
of Environment and Forestry), Yaya Rayadin
orangutans (1,700 orangutans).
(East Kalimantan Forum/ KORAN), Yulita
Kabangnga (Kutai National Park Authority) Some populations in Kalimantan are
reintroduced: Beratus in Landscape Beratus,
Introduction
Sungai Wain in Landscape Sungai Wain and
Pongo pygmaeus morio is one of the Kehje Sewen in Landscape Wehea-Lesan. The
three currently recognized subspecies of number of orangutans in Beratus landscape
the Bornean orangutan (Goossens et al. is estimated to be 30 (in 40,000 ha), from a
2009). This subspecies is found in the State total of 349 orangutans released between
of Sabah (Malaysia) and the Province of 1997 and 2002. The total area of Beratus
East Kalimantan (Indonesia). It is assumed landscape exceeds 200,000 ha and consists
that it no longer persists in the Province of of Beratus Protection Forest, PT. ITCI and PT.
North Kalimantan. There are 11 landscapes BFI logging concessions. A through survey
in Sabah recognized as this taxon’s major over a larger area is needed to provide better
habitat, with a total population size are information about orangutans. The Sungai
11,730 (SD ±1,560) orangutans. Overall, Wain landscape is in a critical situation since
P.p. morio’s populations in Sabah are in a the Sungai Wain Protection Forest was reduced
stable situation because most of the habitats as a result of forest fire, encroachment, road
are in the Protection Forest. It is estimated construction (highway) in some locations, as
that 4 of the 11 landscape habitats host well as Balikpapan botanical garden. A study
more than 1,000 orangutans each, i.e: Tabin on Sungai Wain is urgently needed to update
Range landscape (1,250 orangutans), Central information about the area and to identify
Forest Range landscape (5,320 orangutans), appropriate next steps for supporting the
Lower Kinabatangan Range landscape (1,500 remaining orangutans. It is estimated that the
orangutans) and North Kinabatangan range Kehje Sewen forest can support around 150
(2,030 orangutans). The three population units orangutans. The number in the rehabilitation
within the Central Forest Range Landscape, center exceeds 200 and additional forest will
i.e: Danum Valley, USM, Forest Foundation be needed to house these animals.

40 Orangutan Population and Habitat Viability Assessment

Two priorities for conserving P.p. morio were agriculture, such as palm oil development
identified as: Kutai National Park-Bontang and also timber plantation. Encroachment
Landscape and the forested area in Wehea- for small scale agriculture and illegal logging
Lesan PF Landscape, which part of it located was also considered a serious threat for P.p.
inside the concessions, and the customary morio sustainability. The priority strategies
forest of Wehea. The distribution of P.p. for mitigating threats to P.p. morio are:
morio is shown in Figure 4 with agreed meta- improving law enforcement and establishing
population boundaries indicated. better spatial planning. Other recommended
strategies are listed in Table 8.
The main threat to P. p morio populations in
Kalimantan is habitat conversion for industrial

Table 8. Summary of the main threats and recommended mitigation strategies, for P.p. morio

Threats Priority strategies

Encroachment: small Law enforcement.
scale agriculture Developing sustainable alternative livelihoods for local communities.
Strengthening monitoring and patrolling capacity.
Improving the capacity of forest management units.
Intensive education and awareness programs.
Strengthening multi-stakeholder partnerships (local, national and
international).
Illegal logging Law enforcement.
Encouraging local communities to plant local timber species on their land/
garden, for their own use or to meet local demand (i.e. housing).
Strengthening monitoring and patrolling capacity/informant networks.
Intensive education and awareness programs.
Strengthening multi-stakeholder partnerships (local, national and
international).
Conversion for Law enforcement.
industrial agriculture Moratorium (no new permits and no clearing of forest within concessions).
Building corridors connecting High Conservation Values (HCV) areas within
concessions to viable forest patches/landscapes. Where not possible and
where this threatens the orangutan population of orangutan, the last resort is
to relocate to a suitable area with full responsibility taken by the company (i.e.
budget, location and other resources).
Strengthening monitoring and patrolling capacity.
Road construction Revising spatial planning to reduce fragmentation of orangutan habitat from
road development.
Poaching/Hunting Law enforcement.
Promoting better spatial planning.
Intensive education and awareness program.
Developing sustainable alternative livelihood for local communities.
Strengthen multi-stakeholder partnerships (local, national and international;
including private sector and local community).

Orangutan Population and Habitat Viability Assessment 41

Figure 8. Map of Borneo showing meta-population designations for Pongo p. morio.

42 Orangutan Population and Habitat Viability Assessment

Pongo pygmaeus pygmaeus Another highly populated area is in Danau
Sentarum NP and its buffer zone in West
Working group members:
Kalimantan. This habitat is also a priority site
Albert Tjiu (WWF Indonesia), Mohamad Arif
because it is the second largest orangutan
Rifqi (FORINA), Pahrian Ginawira Siregar
habitat with half of the forested area protected
(FORINA), Sri Suci Utami Atmoko (FORINA-
as a national park and is proposed for
UNAS), Muhammad Syamsuri (FOKKAB),
connection to Betung Kerihun NP landscape
Melvin Gumal (WCS Malaysia), Sylvia Ng
by the Labian-Leboyan wildlife corridor. Small
(WCS Malaysia), Drajat Dwi Hartono (MoEF),
populations can still be found in Ulu Sebuyau
Fitty Machmudah (MoEF).
National Park and Sedilu National Park in
Introduction Sarawak, as well as some fragmented areas in
coastal West Kalimantan, both in the northern
Pongo pygmaeus pygmaeus is one of the three
and southern parts. Meanwhile, two trans-
currently recognized subspecies of Bornean
boundary areas: Klingkang Range National
orangutan (Goossens et al. 2009) and is
Park in Sarawak and Sintang Utara Protection
categorized as Critically Endangered by IUCN
Forest in West Kalimantan; and Bungoh
(IUCN, 2016). This taxon is found in West
National Park in Serawak and Gunung Nyiut
Kalimantan (Indonesia) from north of the
Nature Reserve-Penrisen Protection Forest in
Kapuas River to the eastern part of Sarawak
West Kalimantan, are also suspected to still
(Malaysia). It has the smallest range of the three
support small populations of orangutans.
Bornean orangutan subspecies, with only
approximately 2,680 individuals remaining Poaching remains the major threat to
in West Kalimantan and 1,840 individuals in orangutan survival over most of the range
Sarawak. The core populations are centered occupied by P.p. pygmaeus, although two
in a trans-boundary conservation area that major populations and some other smaller
covers Betung Kerihun National Park in West ones reside in protected areas. In addition,
Kalimantan and Batang Ai National Park/ large numbers that existed on the western
Lanjak Entimau Wildlife Sanctuary complex in side of West Kalimantan have been lost due
Sarawak, also known as Betung Kerihun NP to recent forest conversion for industrial
and BALE landscape. These protected areas agriculture, such as palm oil and timber
are together the largest contiguous orangutan plantation. The remaining forested areas in
habitat for P.p. pygmaeus, for which there are this location are under very high pressure
limited research publications. This area would from habitat loss, conflict killing and hunting.
probably have the best chance of supporting The other priority threat affecting orangutan
a viable population and currently is the most sustainability is road construction along
secure area for orangutans because the land the border in Kalimantan. The border road
use status is national park, wildlife sanctuary project will construct 171 km of road in West
and/ or district strategic zone (Kawasan Kalimantan and 78 km in North Kalimantan.
Strategis Kabupaten), which means that most This project will potentially fragment
of this area is already protected.

Orangutan Population and Habitat Viability Assessment 43

orangutan populations, increase forest access Summary of priorities
and lead to encroachment and settlement Priority sites for Pongo pygmaeus pygmaeus:
expansion in orangutan habitat, such as
Sintang Utara Protection Forest, Gunung • Betung Kerihun NP and BALE
Nyiut Nature Reserve, Penrisen Protection landscape: together represent the
Forest, and Betung Kerihun National Park. largest contiguous area of orangutan
Fire is not considered an important threat habitat for P. p. pygmaeus, with much
in P.p. pygmaeus areas, even in Danau of the area already under protection.
Sentarum NP which is commonly burned by This was considered by the group to
the local community (fishermen) during the offer the best chance of supporting
dry season, but the burning does not take a long-term viable population of
place in orangutan habitat. The main strategy orangutans.
proposed for mitigating threats is a moratorium • Danau Sentarum NP: prioritised as
on habitat conversion. This moratorium must the second largest area of orangutan
include no new permits that could potentially habitat, with half of the forested
convert orangutan habitat, and no clearing area protected as a national park and
of remaining forest within concessions. There because of its potential connection
is also a need to increase intensive study of to Betung Kerihun landscape by the
the behaviour and ecology of P.p. pygmaeus. Labian-Leboyan wildlife corridor.
Other recommended strategies for threat The main threat to P.p. pygmaeus is conversion
mitigation are listed in Table 9. The distribution for industrial agriculture and the highest
of P.p. pygmaeus is shown in Figure 5 along priority mitigation strategy is moratorium (no
with the meta-population boundaries agreed new permits and no clearing forest within
at the PHVA workshop. concessions).

c Arif Rifqi

Figure 9. Orangutan habitat in Danau Sentarum landscape.

44 Orangutan Population and Habitat Viability Assessment

Figure 10. Map showing designated meta-population polygons for Pongo p. pygmaeus

Orangutan Population and Habitat Viability Assessment 45

 Table 9. Summary of the main threats and recommended mitigation strategies for
Pongo pygmaeus pygmaeus.
Threats Strategy
Human orang-utan conflict and Law enforcement.
poaching
Promote better spatial planning.
Intensive education and awareness programs.
Develop sustainable alternative livelihoods for local
communities.
Strengthen multi-stakeholder partnerships (local, national and
international; including private sector and local community).
Fire Law enforcement.
Strengthen monitoring and patrolling capacity.
Promote better spatial planning.
Intensive education and awareness programs.
Strengthen multi-stakeholder partnership (local, national and
international; including private sector and local community).
Illegal logging Law enforcement.
Encourage local community to plant local timber species in
their land/garden for their own use or for local demand (i.e.
housing).
Strengthen monitoring and patrolling capacity/informant
network.
Intensive education and awareness programs.
Strengthen multi-stakeholder partnerships (local, national and
international).
Conversion to industrial law enforcement.
agriculture
Moratorium (no new permit and no clearing forest within
concession).
Building a corridor connecting HCV area within concession
to viable forest patch/landscape, if not possible and the
population of orangutans is threatened, the last resort is to
relocated them to a suitable area with full responsibility taken
by the company (i.e. budget, location and other resources).
Strengthen monitoring and patrolling capacity.
Encroachment: small scale Law enforcement.
agriculture
Developing sustainable alternative livelihood for local
communities.
Strengthen monitoring and patrolling capacity.
Improve capacity of forest management unit.
Intensive education and awareness program.
Strengthen multi-stakeholder partnerships (local, national and
international).
Road construction Revise spatial planning to reduce fragmentation of orangutan
habitat caused by road development.

46 Orangutan Population and Habitat Viability Assessment

Pongo pygmaeus wurmbii
Working group members: Tanjung Puting National Park + Rimba Raya
Ade Soeharso (OF-UK), Ari Meididit (WWF (4,160 individuals). The other 6 habitats of
Indonesia), Azhari Purbatrapsila (OF-UK), this taxon combined, support more than
Bernat Ripoll (Borneo Nature Foundation), 1,000 individuals, i.e: Katingan (3,750
Birute B. Galdikas(OFI), Chairul Saleh (WWF individuals), Gn.Palung National Park-Gn.
Indonesia), Ettie Tatiana (BKSDA Kalteng), Tarak PF (2,150 individuals), Mawas (1,790
Fajar Dewanto (OFI), Gail Campbell-Smith individuals) and Rungan Timur (Mungku Baru:
(YIARI), Hendrik Segah (FORKAH), Iman Sapari 1,700 individuals).
(YAYORIN), Jamartin Sihite (BOSF), Karmele
Comparison of P.p.wurmbii numbers from
Llano Sanchez (YIARI), Renie Djojoasmoro
the 2004 (Wich et al. 2008) and 2016
(OFI), Robert Yappi (OFI), Simon Husson
PHVA workshops. If we compare just those
(BOSF), Yarrow Robertson (OF-UK).
populations which were included in both the
Analysis editors: Simon Husson, Sri Suci 2004 PHVA and 2016 PHVA, we have a 2016
Utami-Atmoko, Gail Campbell-Smith and figure of 25,447 – 34,962 (in prep.). This
Bernat Ripoll Capilla therefore represents a decline in this subset
of the P.p.wurmbii population of 26%, when
Introduction considering the lower 2016 estimate, to no
Pongo pygmaeus wurmbii is one of the three decline at all at the upper estimate. Eight
currently recognized subspecies of Bornean of the eighteen P. p wurmbii populations
Orangutan (Goossens et al. 2009) and is identified were assessed to be declining
categorized as Critically Endangered by IUCN (Gunung Palung National Park, Bukit Baka
(IUCN, 2016). This taxon is found in West National Park, Tanjung Puting National Park,
Kalimantan (Indonesia) from the south part of Sabangau National Park, Arut-Belantikan,
the Kapuas River to the eastern Barito River Eastern Schwaner (Bukit Raya, Kahayan-
in Central Kalimantan (with a few individuals Sambah, Sambah-Katingan), Sabangau-
in South Kalimantan province). This taxon Kahayan and Tanjung Kaluang. As this decline
has the largest population of the three is not uniform and indeed several areas have
Bornean Orangutan subspecies, with 38,200 higher estimated populations in 2016, such
(SD±2760) individuals remaining. These occur as Rongga-Perai, Rungan Timur, Katingan
in 10,170,196 ha of potentially suitable and Seruyan Hulu. In other areas where
habitat, although they are absent (except for they were thought present in 2004, they are
four recently reintroduced populations) from now thought to have been absent for a long
habitat units totaling 3,639,949 ha, resulting period of time. Additionally, 19-22% of the
in an effective 2016 range of 6,530,247 ha. current orangutan population lives in habitat
The core populations are centered in Western units which were not included in the 2004
Schwanner (Arabela, Rongga-Perai, Seruyan PHVA. Therefore, more than anything else,
Hulu: 9,460 individuals), Sabangau National is that we are still refining our knowledge
Park + surrounds (5,750 individuals) and of the distribution and density of orangutan

Orangutan Population and Habitat Viability Assessment 47

populations throughout their range. Periodic of the range occupied by P. p. wurmbii. In 2015,
assessments such as this one act as a catalyst forest fires in Kubu Raya, West Kalimantan, and
for more fieldwork. Palangkaraya, Central Kalimantan, destroyed
significant areas of orangutan habitat. Over
We estimate that 32-38% (11,891-14,399
half of the population of this sub-species, 57-
individuals) of the current P.p.wurmbii
60% (18,858-25,549 individuals) are found
population occur in major protected areas,
in areas that are predominantly peat-swamp
i.e.: Sabangau National Park, Tanjung Puting
forest habitat and at elevated risk of fire (in
National Park, Gunung Palung National Park,
prep.). Forest conversion for agricultural
and Lamandau Wildlife Reserve. Populations
purposes is also considered a serious threat
in these areas were considered to be stable.
to orangutan habitat and can be a trigger for
Two locations support reintroduced or
human - orangutan conflict. Priority strategies
translocated populations, i.e.: Batikap Nature
for mitigating the threats to P. p. wurmbii
Reserve in Murung Raya and Bukit Baka-Bukit
are: enforcing the law, a moratorium on the
Raya National Park.
conversion of peat land and natural forest to
other purposes, and harmonizing regulations
Forest fires and habitat conversion remain the
among ministries regarding forest fires and
major threats to orangutan survival over most
conversion.

Table 10. Summary of the main threats and recommended mitigation strategies for
Pongo pygmaeus wurmbii.

Threat Strategies
- law enforcement
Encroachment: small scale
- socialization/awareness
agriculture
- alternative economic livelihoods
Encroachment: small scale extensive - law enforcement and improved capacity of local and
agriculture central government
- moratorium (no new permits, no clearing forest within
concessions);
- evaluate cost and benefit of long-term palm oil plantation
with transparent and publicly accessible results;
- good governance;
- promote transparency of supply chains;
- law enforcement through prosecution of law-breaking
companies;
Conversion: for industrial
- promote “responsibility for the threatened orangutan”;
agriculture
- harmonise the needs of land set-aside for conservation
with plantation concessions and land resources (BPN)
regulations
- promote a landscape approach; building corridors
connecting HCV areas within their concession into
neighbouring viable forest patches;
- operate patrols (SATGAS) in concessions;

- encourage effective replanting policies

48 Orangutan Population and Habitat Viability Assessment

 - closure of illegal roads

- revise spatial planning to reduce fragmentation of

orangutan habitat from road development
Road construction
- patrol and law enforcement operation

- alternative economic livelihoods

Settlement - socialization/awareness efforts
- law enforcement

- socialization/awareness

- alternative economic livelihoods

- encourage local community replanting schemes on

Logging: illegal their lands for community/personal use (i.e. house
refurbishment)

- strengthen monitoring and patrolling capacity/informant

networks (community patrol teams for example)

- strengthen multi-stakeholder partnership (local, national

and international)
- law enforcement

Logging: low impact - socialization/awareness

- alternative economic livelihoods

- law enforcement

- socialization/awareness

- alternative economic livelihoods

Logging: high impact
- strengthen monitoring and patrolling capacity/informant
networks (community patrol teams)

- strengthen multi-stakeholder partnership (local, national

and international)
- moratorium (no new permits, no clearing forest within
concessions);
- evaluate cost and benefit of long-term timber (all types)
with transparent and publicly accessible results;
- good governance;
- promote transparency of supply chains;
- law enforcement through prosecution of law-breaking
Timber plantation companies;
- promote “responsibility for the threatened orangutan”;
- promote a landscape approach; building corridors
connecting HCV areas within their concession into
neighbouring viable forest patches
- operate patrols (SATGAS) in concessions

- encourage effective replanting policies

Absence of forest management unit - West Kalimantan

Orangutan Population and Habitat Viability Assessment 49

Figure 11. Map showing designated meta-population polygons for Pongo p. wurmbii

50 Orangutan Population and Habitat Viability Assessment

 Orangutan Population Viability
Analysis Modelling Report

Modeler: Kathy Traylor-Holzer, IUCN SSC CBSG

Introduction PVA objectives

The purpose of this Population Viability Participants at the 2016 PHVA workshop
Analysis (PVA) is to provide an assessment identified the following questions to be
of the relative viability of wild orangutan addressed by this PVA:
populations living on Sumatra and Borneo
1. What is the projected viability of current
through the development of a population
orangutan populations given the best
simulation model based on the best available
estimates of population size, threats and
information. This assessment identifies
management?
those factors that most influence orangutan
population viability and explores the impacts 2. What is the projected impact on orangutans
of increases or reduction of threats. This PVA of the construction of roads through
provides an update to previous orangutan orangutan habitat (e.g., in West and East
PVAs conducted by CBSG in 1993, 2004 Leuser, in West and East Batang Toru)?
and 2005 in connection with orangutan 3. What is the smallest population size
conservation planning efforts (Tilson et al. that can meet the agreed standards for
1993; Singleton et al. 2004; Ellis et al. 2006), a Minimum Viable Population (MVP)?
and is designed to inform the next Orangutan How does this size change with different
Conservation Strategy and Action Plan. conditions or threat levels?

Orangutan Population and Habitat Viability Assessment 51

4. What is the smallest current population that actions for a population or species and to
could meet the MVP standard if allowed identify research needs. Such an evaluation
space to grow larger (e.g., reintroductions of population persistence under current and
into a new area, additional habitat added varying conditions is commonly referred to as
to an existing area)? a population viability analysis (PVA).

5. What level of periodic supplementation

The simulation software program Vortex
would be needed to maintain the viability
(v10.2.6) (Lacy and Pollak 2017) was used
of small populations below the MVP?
to examine the viability of orangutan
6. What is the viability of populations populations on Sumatra and Borneo based
established using a specified reintroduction on previous PVA models and using updated
scheme? population and threat information. Vortex is
a Monte Carlo simulation of the effects of
For the purposes of this PVA, the participants
deterministic forces as well as demographic,
agreed to the following definition of a ‘viable
environmental, and genetic stochastic events
population’:
on wild populations. Vortex models population
A viable population is one with less than dynamics as discrete sequential events that
1% probability of extinction in 100 years occur according to defined probabilities. The
(PE100y < 1%) and less than 10% risk of program begins by creating individuals to
extinction in 500 years (PE500y < 10%). form the starting population and then steps
through life cycle events (e.g., births, deaths,
Additional measures such as population trend
dispersal, catastrophic events), typically on an
and genetic diversity also are pertinent to
annual basis. Events such as breeding success,
assessing viability. Due to the long generation
sex at birth, and survival are determined based
time (~30 years) of this species, it is appropriate
upon designated probabilities. Consequently,
to consider population status over multiple
each run (iteration) of the model gives
generations to detect impacts of threats and
a different result. By running the model
stochastic processes on long-term viability.
hundreds of times, it is possible to examine the
probable outcome and range of possibilities.
Introduction to PVA and Vortex
For a more detailed explanation of Vortex and
Computer modelling is a valuable and versatile
its use in population viability analysis, see Lacy
tool for quantitatively assessing risk of decline
(2000) and Lacy et al. (2017).
and extinction of wildlife populations, both
free ranging and managed. Complex and Model development and data sources
interacting factors that influence population
A Vortex population model for orangutans was
persistence and health can be explored,
developed at the 2004 Orangutan PHVA and
including natural and anthropogenic causes.
modified to reflect differences in orangutan
Models can also be used to evaluate the
life history in Sumatra and Borneo (Singleton
effects of alternative management strategies
et al. 2004). Data for age- and sex-specific
to identify the most effective conservation
mortality rates, reproductive lifespan, and

52 Orangutan Population and Habitat Viability Assessment

inter-birth interval for Sumatran orangutans
a.
were taken from 30+ years of data from a
study site at Ketambe (Wich et al. 2004). This
Sumatran orangutan model was revised at
the 2005 Sumatran Orangutan Conservation
Action Plan Workshop to provide updated
future projections of population viability for
Sumatran orangutans based upon revised
estimates of habitat loss or alteration and the
subsequent effects on orangutans (Ellis et al.
2006). b.

This existing Vortex orangutan model served

as the basis for this current PVA. Input values
on life history parameters were reviewed by
the 2016 PHVA participants and revised as
appropriate. Updated estimates on current
population size and structure, available
habitat (carrying capacity), projected future
habitat loss, and projected removal rates were
provided by PHVA working groups to inform Figure 12. Percent adult females breeding with
density (for population of 600) for a) Sumatran
new viability projections (also see working and b) Bornean models.
group reports in this report).
of five female mates per year. New mates
Model Parameters and Input are selected each year. All adult males were
Values considered to be in the breeding pool (i.e.,
The input values used for this model are potential breeders) in the model.
described below – also see Singleton et al. 2004
and Ellis et al. 2006 for details. The base model Reproduction lifespan: Reproduction was
was developed for Sumatran orangutans, modelled as beginning at age 15 for females
with minor life history adjustments made for and age 20 for males, and indicates the
Bornean populations as noted. mean age at which first offspring are born,
not conceived (mating). Information from
Reproductive rates Ketambe at the 2006 PHVA reported the
Mating system: Orangutans have a age of first reproduction typically to be 15
promiscuous breeding system. Both sexes years for females and 25 years for males;
may have multiple mates, although animals this was revised to age 20 for males by 2016
may breed with the same mate(s) for several PHVA participants. One female at Ketambe
years. Short-term polygyny was used in the produced offspring at about 50 years of age;
model, with adult males limited to a maximum this was accepted as a plausible maximum

Orangutan Population and Habitat Viability Assessment 53

age of successful reproduction for females. Environmental variation (EV) was set at 5.5%
Males were assumed to be reproductive their (approximately 33-50% of the mean). Given
entire lives. Maximum age for both sexes was the lifespan of this species, year-to-year
set at 60 years. Age of first reproduction was fluctuations in demographic rates tend to
set at age 18 for males and maximum age (for average out; therefore this value probably has
both sexes) at 55 years in the Bornean model. little effect on population projections.

Reproductive rate: Density-dependent Only a single offspring were modelled (no

reproduction was modelled by a functional twins); in rare instances of the observed birth
relationship between population density and of twins in the wild, at least one does not
percent of females producing offspring, as survive. Sex ratio at birth was modelled as
shown in Figure 7. For the Sumatran model, 55% male. Data from a number of field sites
this relationship represents 15.4% of adult suggest a male bias in births.
females reproducing at low density (interbirth
Mortality rates
interval IBI = 6.5 years), declining to 11.1%
at carrying capacity (IBI = 9 years). An Allee Age- and sex-specific mortality: The long
effect was added to depress breeding at lifespan and slow reproductive rate of this
very low density. This function was modified species suggest low rates of natural mortality.
for different population sizes to produce a Mortality rates were extrapolated from over
curve that peaks at 15.4%. Average IBI for 30 years of field data from Ketambe for the
wild orangutans in Ketambe is 8.7 years and 2004 PVA model; these rates were reduced
under 8 at Suaq Balimbing, which translates for this PVA based on the latest data from
to populations at 90-97% capacity on this Ketambe and Suaq. Mortality was increased
functional curve. Test runs of this model in the upper age classes for Bornean so that
(N=K=1500) result in the population stabilizing ~5% of the individuals reach maximum age.
at ~ 90% K (IBI = ~8 years on the curve). Juvenile males are thought to experience
Bornean orangutans have a slightly shorter higher mortality than females. Adult mortality
lifespan and faster reproduction; breeding is believed to be low. Environmental variation
rates were set at 16.7% (IBI = 6) at low density (EV) around mortality rates was set at 50% of
and 11.8% (IBI = 8.5) years at capacity. In the mean. EV for survival and for reproduction
addition, the shape of the function was were correlated in the model.
modified to produce a longer range of peak
Inbreeding depression: Inbreeding is thought
reproduction. Observed IBI for wild Bornean
to have major effects on reproduction
populations are range from 7.1 to 7.8 years,
and survival of species, especially in small
which would translate to populations at 90-
populations, and so was included in the
96% capacity on this functional curve. Test
model (as reduced survival of inbred offspring
runs of this model (N=K=1500) result in the
through their first year). The impact of
population stabilizing at ~93% K (IBI = 7.43
inbreeding was modelled as 6.29 lethal
on the curve).
equivalents as a conservative estimate based

54 Orangutan Population and Habitat Viability Assessment

 carrying capacity, with individuals distributed
Sumatran Bornean
across age-sex classes according to a stable
Age class Females Males Females Males
age distribution that is characteristic of the
(annual (% (% (% (%
%) mort.) mort.) mort.) mort.) mortality and reproductive rates in the model.
0-2 3 3 3 3 Initial individuals were assumed to be unrelated
2–8 1 3 1 3 unless otherwise noted. Populations were
8 – 11 2 3 2 3 modelled as isolated populations, with no
11 – 15 1 1 1 1 migrants and no augmentation (translocations
15 – 20 1.5 1 1.5 1 or releases) unless otherwise noted. Scenarios
20 - 41 1.5 1.2 1.5 1.2 for specific existing orangutan populations
41 - 46 5 5 5 5 were parameterized based on inputs from
46 - 51 10 15 15 15 the PHVA working groups (see Population-
51 - 56 15 20 25 25 Specific Models).
56 - 60 20 25 - -
Habitat loss and fragmentation: Carrying
Table 11. Model age- and sex-specific annual
mortality rates. capacity was assumed to be constant for
upon a review of inbreeding effects in wild sensitivity testing and MVP exploration
mammalian and avian populations (O’Grady unless otherwise noted. In MVP scenarios
et al. 2006), with 50% of the effect of modelling habitat loss, rates were applied to
inbreeding due to recessive lethal alleles the remaining habitat each year, such that
(100% for populations >5000). the actual amount of habitat loss is not linear
but diminishes over time; this was done to
Catastrophes: Disease and fire are among
match the method chosen to model habitat
those catastrophes thought to impact wild
loss in actual orangutan populations. Habitat
orangutan populations. In the absence of
changes were modelled as a permanent
sufficient data for specific catastrophes, a
reduction in carrying capacity for orangutans,
collective ‘generic’ catastrophe was modelled
which not only reduces K but also removes
based upon a review of severe catastrophes in
individuals from the population when N>K
88 vertebrate species by Reed et al. 2003. This
proportionately across all age-sex classes.
was modelled as a 14% risk per generation
Habitat loss rates for actual orangutan
of a 50% reduction in the population, which
populations were estimated by the PHVA
translates to an annual risk of 0.46% annual
working groups.
risk (severe catastrophe hitting approximately
once every 215 years). Direct loss of orangutans: No additional loss
of orangutans due to anthropogenic causes
Population inputs
(e.g., poaching, illegal trade) was included
Initial population size (N) and carrying in the ST or MVP scenarios unless otherwise
capacity (K): Scenarios for sensitivity testing noted. Additional losses for actual orangutan
(ST) and exploration of MVP under various populations were estimated by the PHVA
conditions were initiated with populations at working groups.

Orangutan Population and Habitat Viability Assessment 55

Model runs and timeline model to artificially truncate populations that
Due to the long-lived and slowly reproducing exceed K except in instances of habitat loss.
nature of this species, orangutan populations
Sensitivity Testing
were modelled for 500 years (~16 generations)
Recognizing that there is some uncertainty
so that long-term population trends could be
around model input parameters, sensitivity
observed and results compared to population
testing (ST) was conducted by varying a
viability goals. Results are presented for
single parameter at a time to assess the
both 100 years and 500 years. Note that
sensitivity of the model results to different
uncertainty in projection results increases over
input values. All ST scenarios were run for
time due to stochastic processes. In addition,
500 years with 500 iterations with an initial
it is unlikely that conditions are adequately
population of 500 Sumatran orangutans at
understood or will remain constant to allow
capacity (K=500) with no future reduction in
us to accurately predict population status so
K. While stochastic r is often used to assess ST
far into the future. All scenarios were run for
results, this metric is of less value here given
a minimum of 500 iterations.
that these populations are near K and r is
Deterministic results small; thus other metrics such as mean final
The baseline model for orangutans describes a population size and probability of extinction
population that shows positive deterministic (PE) were used. Detailed results can be found
growth (r = 0.014 for Sumatran, r = 0.016 at the end of this section.
for Bornean) in low density conditions. This
Demographic Sensitivity
is the average population growth expected
Mortality: Juvenile, sub-adult and adult
based on mean fecundity and mortality rates
mortality rates were varied independent by
in the absence of inbreeding, human-related
+10% and +20%, for males and females.
mortality, and stochastic processes (e.g.,
Male mortality rates and female juvenile
shortage of mates, skewed sex ratio). This
mortality have little impact on model results.
is a plausible growth rate for a large, long-
As might be expected in a long-lived, slow
lived and slowly reproducing species such as
reproducing polygynous species, adult female
the orangutan. Population growth is reduced
mortality (and, to a lesser extent, female
under crowded conditions where resources
sub-adult mortality) does affect population
are limited and the carrying capacity of the
growth and the ability of the population to
habitat is reached. In these conditions, the
recover from stochastic declines, resulting in
percent of breeding females drops to 11.1%
a slow decline in mean population size over
(Sumatran) or 11.8% (Bornean), resulting
time (Figures 8 & 9). Overall viability remains
in almost zero growth rate (rSumatran = 0.002;
high, with high gene diversity and almost no
rBornean = 0.004). Thus in the model, populations
risk of extinction. Final mean population sizes
living in saturated conditions regulate their
range from 442 (20% lower mortality) to 394
population size by breeding just enough to
(20% higher mortality).
balance the population around the habitat’s
carrying capacity. This negates the need for the

56 Orangutan Population and Habitat Viability Assessment

 Figure 13. Mean population size at Y500 for mortality rates tested (K = 500). Black dot = base
model value.

As might be expected in a long-lived, slow to age 45; thus, reducing maximum age to
reproducing polygynous species, adult female 45 years can have a significant impact on the
mortality (and, to a lesser extent, female reproductive potential of the population.
sub-adult mortality) does affect population
Changing the interbirth interval at low density
growth and the ability of the population to
(6 to 7 years) and at high density (8 to 9
recover from stochastic declines, resulting in
years) each also have a similar impact on final
a slow decline in mean population size over
population size. IBI at low density affects the
time (Figures 8 & 9). Overall viability remains
ability of the population to grow following
high, with high gene diversity and almost no
decline, while IBI at K impacts the population’s
risk of extinction. Final mean population sizes
ability to maintain its size in saturated habitat.
range from 442 (20% lower mortality) to 394
(20% higher mortality).
Changes in birth sex ratio have an even
larger impact over the range of values tested
Reproduction: Varying the age of first
(male:female = 50:50; 55:45, 60:40). Male-
reproduction from 14 to 16 years (base model
biased sex ratios lead to relatively fewer
value = 15) has an almost identical effect
breeding females, which limits population
on model results as changes in adult female
growth in polygynous species. A 60% male
mortality of +20%. Reducing maximum age
bias results in a final mean N500 = 330.
from 60 to 55 or 50 has little effect but does
negatively impact the population at Max
Demographic impacts: The general conclusion
Age = 45 years. Survival rates used in the
of demographic sensitivity testing is that
model result in about 44% of females living
population size (and growth) is impacted

Orangutan Population and Habitat Viability Assessment 57

by the number of breeding females, their of 6.29 lethal equivalents (LEs) is a ‘rule of
reproductive lifespan, and their productivity thumb’ estimate for incorporating inbreeding
(IBI). Large populations (e.g., N > 500) are impacts into the PVA. This is implemented as
viable over the range of values tested (PE500 reduced first-year survival of inbred infants
< 0.004) and on average maintain N at 66- and becomes more severe as inbreeding levels
95% of K with high gene diversity (> 95%). rise. Sensitivity analysis explored halving and
Of course, higher rates of ‘mortality’ (whether doubling this value (to 3.145 and 12.58 LEs,
it be deaths or other sources of loss of female respectively) as well as removing all inbreeding
orangutans from the population) will have effects. Genetic load (as LEs) affected the
greater negative impacts. While some of model results in a manner and magnitude
these demographic traits cannot be easily similar as the above demographic effects,
influenced, model results suggest that the loss with some impact on mean population size
of breeding females can be especially harmful but little effect on gene diversity or extinction
to wild orangutan populations. Management risk.
actions that minimize loss of adult females
Since the base model assumes that all
(e.g., poaching) and disturbance to breeding
orangutans in the initial population are
behavior should promote population
unrelated, inbreeding levels build slowly in a
sustainability.
population of 500 individuals and only reach
Genetic sensitivity mean coefficient of inbreeding (F) = 0.0286 at
Genetic load: In the absence of species- or Year 500. Inbreeding will accumulate faster in
population-specific inbreeding depression small populations; for example, a population
data, the recommended conservative value of 150 orangutans reaches mean F = 0.1592

Figure 14. Mean population size over time with adult base mortality rates (black line),
and + 20% of base rates.

58 Orangutan Population and Habitat Viability Assessment

 Figure 15. Mean population size at Y500 varied across genetic load (LE) and initial kinships
(relatedness) in the population.

in 500 years, which is well above the genetic low (< 5% over 500 years) for all scenarios
kinship between half siblings (0.1250). As a except one (LE=12.58, Kin=0.1250), inbred
general rule, inbreeding effects often are seen populations show decline and reduced gene
in populations with inbreeding > 0.10, which diversity. Populations modelled under the
corresponds to ~90% gene diversity. Thus, default LE value are vulnerable to inbreeding.
smaller populations are likely to be more As orangutan populations become increasingly
vulnerable to inbreeding impacts and genetic fragmented and isolated from other habitat
load. fragments, inbreeding may impact long-term
viability without genetic augmentation.
Initial kinships: In order to separate inbreeding
effects from other stochastic processes Impacts Of Population Size:
affecting small populations, a set of scenarios Defining Minimum Viable
were run by varying levels of kinship among Population Size
the founding individuals (initial kinships = Small populations are vulnerable to decline
0, 0.0156, 0.03125, 0.0625, 0.1250) for and extinction due to demographic and
a population of 500 individuals. Figure 10. genetic stochastic processes, including
demonstrates the interaction between the demography stochasticity, environmental
severity of inbreeding depression measured by variation, catastrophic events, genetic drift,
LE and the level of inbreeding in the starting and inbreeding (Shaffer 1987). Inbreeding
population. If the population is genetically accumulates faster in small populations,
diverse, the genetic load has relatively small reducing survival and reproduction that, in
impact. With increasing relatedness in the turn, leads to further decline. This feedback
population, increased LE can lead to significant loop has been termed the “extinction vortex”
population decline. While extinction risk is (Gilpin and Soulé 1986) and may drive a

Orangutan Population and Habitat Viability Assessment 59

small population to extinction in the absence threats and stochastic processes on long-term
of anthropogenic threats such as poaching. viability.
Minimum viable population (MVP) is the term
Scenarios were run for both Sumatran and
historically used to denote the population size
Bornean orangutan populations ranging
below which extinction risks are unacceptably
from 5 to 1500 individuals (N0=K). Initial
high. Shaffer initially defined MVP as the
founders were assumed to be unrelated; as
smallest isolated population having a 99%
demonstrated earlier, viability will decline
chance of remaining extant for 1000 years.
more quickly if the initial animals are related
However, risk tolerance is a societal construct,
or are genetically impoverished. Model results
and stakeholders vary in their definition
at 100 years and at 500 years (probability of
of unacceptable risk. Thus MVP will vary
extinction PE, mean population size N, and
depending upon each group’s definition of
gene diversity GD) can be seen in Table 17.
‘viable’.

To meet the MVP definition based on PE in

Participants at the 2016 Orangutan PHVA
100 and 500 years as proposed by the PHVA
defined a minimum viable population for
participants, a population of 150 is needed for
orangutans as one with less than 1% risk
Sumatran orangutans and 100 for Bornean
of extinction in 100 years (PE100 < 1%) and
orangutans (Table 12). Figure 11 illustrates
less than 10% risk of extinction in 500 years
the significant improvement in PE at N>150
(PE500 < 10%). Additional measures such as
for Sumatran orangutans. While populations
population trend and genetic diversity also
of 100-150 may meet these PE criteria, they
are pertinent to assessing viability. To avoid
still demonstrate a slow declining trend
inbreeding depression and to retain genetic
and reduced gene diversity (i.e., inbreeding
adaptive potential, a common genetic target
accumulation). A minimum population of 200
is to retain at least 90% gene diversity –
is needed for both species to retain 90% GD
suggested by Soule et al. 1986 as a reasonable
for 500 years. At least 500 orangutans are
zone between potentially damaging loss
needed to stabilize population size (~85% K)
and tolerable loss of genetic diversity. Due
and avoid decline (Fig. 12). These thresholds
to the long generation time (~30 years) of
would need to be higher if the initial animals
this species, it is appropriate to consider
are related or with increased threats.
population status over multiple (perhaps at
least 10) generations to detect impacts of

60 Orangutan Population and Habitat Viability Assessment

 Table 12. Model results (at Years 100 and 500) for Sumatran and Bornean populations of varying size.

Sumatran Bornean
Pop Size PE100 PE500 N N500 GD100 GD500 PE100 PE500 N100 N500 GD100 GD500
100

5 0.948 1.000 0 0 0.576 -- 0.931 1.000 0 0 0.566 --

10 0.539 1.000 3 0 0.686 -- 0.532 1.000 3 0 0.681 --
25 0.060 0.997 17 0 0.854 0.338 0.045 0.980 18 10 0.858 0.482
50 0.007 0.758 40 4 0.927 0.637 0.007 0.599 42 23 0.929 0.654
75 0.002 0.376 64 20 0.953 0.751 0.001 0.244 66 41 0.965 0.759
100 0.000 0.209 86 41 0.964 0.800 0.000 0.096 90 66 0.965 0.822
150 0.001 0.051 131 90 0.976 0.873 0.000 0.034 137 115 0.977 0.887
200 0.000 0.024 178 139 0.982 0.909 0.000 0.008 185 161 0.983 0.917
250 0.000 0.004 225 183 0.986 0.927 0.000 0.006 237 213 0.986 0.935
500 0.000 0.001 460 423 0.993 0.967 0.000 0.000 475 455 0.993 0.969
750 0.000 0.001 687 645 0.995 0.978 0.000 0.000 716 671 0.995 0.979
1000 0.000 0.000 928 900 0.997 0.984 0.000 0.000 952 924 0.997 0.984
1250 0.000 0.000 1152 1116 0.997 0.987 0.000 0.000 1193 1173 0.997 0.987
1500 0.000 0.000 1410 1329 0.998 0.989 0.000 0.000 1426 1410 0.998 0.990

Figure 16.
Probability of
survival over time
for Sumatran
orangutan
population, varied
by size.

Figure 17. Density

(N/K) over time
for Sumatran
orangutan
population, varied
by size.

Orangutan Population and Habitat Viability Assessment 61

MVP Under Alternative removal due to habitat loss, or any other threat
Conditions that results in the animal no longer being in

Initial relatedness the population. Referring back to the model

input values, the maximum deterministic
Populations with diminished genetic variation
growth rate (at relatively low density with
may have lower demographic rates due to
abundant resources) is 1.4% per year for
inbreeding depression, which can reduce
Sumatran and 1.6% for Bornean orangutans,
viability. If these populations are small, further
with slower growth rates for populations
inbreeding will accumulate faster. Thus, small
near K. Observed growth will be slower yet
inbred populations have a higher extinction
due to the effects of stochastic processes not
risk than small genetically diverse populations.
included in the deterministic rate. Therefore,
The result is that MVP may be higher for
it is not possible for orangutan populations to
inbred populations. A set of models was run
reproduce fast enough to overcome additional
for populations of different sizes (N=K from
annual loss of much more than 1%.
5 to 1500) and at different starting levels
of kinship between orangutans. Results in A set of models was run for populations of
Table 18 illustrate that MVP (based on PE as different sizes (N=K from 5 to 1500) and at
defined by the PHVA participants) increases different rates of annual loss of orangutans
to 200 for Sumatran orangutans and 150 for (across all age and sex classes) of 0.5%,
Bornean orangutans for moderately inbred 0.75% and 1%. Results in Table 13 illustrate
populations. Larger populations are needed that MVP (based on PE as defined by the
to maintain at least 90% gene diversity and PHVA participants) increases significantly
relatively stable population size over time. with continued additional loss, for example,
As with the MVP results presented above for to 750 for Sumatran orangutans and 400
unrelated populations, these results assume for Bornean orangutans. While these MVPs
no additional loss of orangutans due to meet the PE criteria, they result in an average
removals (e.g., poaching) or habitat loss. population size in 500 years of 192 (26%
of K) and 155 (39% of K), respectively. It is
Loss of orangutans
indicative of these populations’ inability to fully
Populations under threat that result in the
recover from stochastic declines. These model
additional loss of orangutans beyond ‘normal’
results assume initial unrelated populations;
mortality have reduced viability. Such losses
the viability of inbred populations under
could be the result of poaching for trade,
continuous threat may be lower.
conflict killing for crop raiding, death or

62 Orangutan Population and Habitat Viability Assessment

 Table 13. MVP based on various criteria for Sumatran and Bornean populations varied by initial kinships
and by rate of loss (annual loss across all age and sex classes). *indicates the %K of an initial population
of 1500 after 500 years.

Sumatran Bornean
PE100 PE500 GD500 PE100 PE500 GD500
Minimum N GD100 N/K500 GD100 N/K500
< < > < < >
for: > 0.90 > 0.8 > 0.90 > 0.8
1% 10% 0.90 1% 10% 0.90
Initial kinship:
0 50 150 50 200 350 50 100 35 200 200
0.0156 50 150 50 250 500 50 150 50 250 250
0.03125 75 200 75 300 600 50 150 75 250 300
0.0625 75 200 100 500 1500 50 150 100 450 450
Rate of loss:
None 50 150 50 200 350 50 100 35 200 200
0.5% 75 300 75 300 -- 70%*
50 200 35 250 850
0.75% 75 400 75 350 -- 55%*
75 250 50 300 --74%*
1.0% 100 750 75 600 --36%* 75 400 50 350 --60%*

Habitat expansion
Populations under 150 Sumatran or 100 Table 14 shows the required K for these small
Bornean orangutans do not meet the viability populations to meet the criteria of PE100 <
criteria set by the PHVA participants. Model 0.01 and PE500 < 0.10. Populations of 50+
scenarios were run to investigate whether orangutans or have the ability to meet the
smaller populations might meet these criteria viability criteria if given habitat to expand.
if provided with additional habitat in which Smaller populations have more difficulty
to expand (e.g., new adjacent habitat, release growing quickly enough to overcome the
of orangutans into new habitat, etc.). Initial demographic and genetic stochastic effects
unrelated populations of 10, 25, 50 and 75 of small size. Some iterations show growth
orangutans were modelled in a habitat with to near K while other runs remain small and
K>100 (Bornean) or K>150 (Sumatran). may eventually go extinct. Expanding K>100
Because the initial populations were at for these populations can be beneficial
relatively low densities they exhibited faster (e.g., decreasing PE500 from 0.980 to <
growth rates than populations near K due to 0.20 for N0=25); however, PE500 <0.10 is
density dependent reproduction incorporated not achievable. For populations under 50,
into the model. No additional threats (losses) periodic supplementation through releases
were included in these models, and no may be needed, alone or in combination
additional orangutans were supplemented to with increased habitat, to meet the defined
the populations. viability criteria.

Orangutan Population and Habitat Viability Assessment 63

 Table 14. Carrying capacity (Kviable) needed to meet PE criteria for viable with initial
population sizes of 10 to 100 orangutans. N500 and GD500 denote the mean N
(+SD) and mean GD at Kviable.

Sumatran Bornean
Pop size (N0) Kviable N500 GD500 Kviable N500 GD500
10 -- -- -- -- -- --
25 -- -- -- -- -- --
50 150 83+50 0.848 125 83+41 0.844
75 150 88+47 0.863 100 59+33 0.818
100 150 89+46 0.873 100 59+33 0.822

Supplementation constructed to evaluate two supplementation

Periodic supplementation (release of animals strategies, in which one young adult female
into the population) can help to offset both was added to the population either: 1) at set
demographic and genetic instability in a small intervals (e.g., every 20 years); or 2) in any
population. Ideally, small populations would year in which the number of adult females in
be carefully monitored and supplemented the population fell below a minimum count.
only when needed (i.e., few breeding age Releases began in Year 5 and did not occur in
adults, very low numbers, poorly balanced the last year of the simulation.
sex ratio). This may not always be practical,
Table 15 shows the rate of supplementation
however, and a more regular supplementation
needed to produce a viable population (using
schedule may be more feasible. In either
the PHVA PE criteria) under both strategies.
case, care should be taken to avoid releases
Careful monitoring of populations and
into populations already at capacity of the
conducting releases based on the results
available habitat.
can substantially reduce the frequency of
A set of models were developed to explore the supplementation needed to keep PE low.
minimum level of supplementation needed to However, a regular and more frequent
promote viable small populations (N = 10 to 50 supplementation schedule leads to a larger
Bornean orangutans). These models assume population size and higher gene diversity
that the initial small population is unrelated, (i.e., healthier population), and also has
which may be a reasonable assumption if the advantage of predictability and no
isolation has occurred recently. In the model, dependence upon monitoring. Adding one
new supplements (i.e., released animals) young adult female every 10 to 35 years
are unrelated to the receiving population (depending upon population size) can
and have the same age- and sex-specific greatly improve the viability of small Bornean
survival and reproductive rates as the resident orangutan populations. Slightly higher rates
orangutans. Models also assume constant K would be recommended for small Sumatran
(no habitat loss or expansion). Models were populations.

64 Orangutan Population and Habitat Viability Assessment

 Very small populations of 10 orangutans time releases are considered (evaluated
present a special case. These small annually for ‘monitored’ populations and at
populations are at risk of losing all adult the release interval for scheduled releases).
males from the population by chance Results in Table 20 indicate that strategic
(demographic stochasticity) and hence releases needed to maintain a very small
stopping reproduction, temporarily or even viable (monitored) population are likely to be
permanently. This risk is large enough such that less intense than scheduled releases not tied
no schedule of female-only supplementation to population status. Raising the minimum
meets the PE criteria for viability. Therefore, criterion from < 2 adult females to <3 adult
scenarios for 10 orangutans included the females leads to a slightly larger and more
provision to supplement an adult male IF genetically diverse population (which is true
none is present in the population at the for larger populations as well).

Table 15. Supplementation rate needed to meet PE criteria for viability with population sizes of 10 to 50 Bornean
orangutans. Scheduled releases occur at set intervals while releases based on monitoring occur on all years that
meet the criterion listed. Releases = one adult female (*and/or one adult male if none are in the population).

Scheduled releases Releases based on monitoring

Pop Ap- Total
Inter- Total re-
size Release N500 GD500 Criterion prox. re- N500 GD500
val leased
(N=K) interval leased
50 1 adult F 35 yr 16 30.7 0.819 <3 AF ~131.5 3.8 22.1 0.763
40 1 adult F 25 yr 20 34.9 0.889 <3 AF ~89.3 5.6 18.6 0.743
30 1 adult F 20 yr 25 22.2 0.846 <4 AF ~46.9 10.7 20.6 0.787
20 1 adult F 13 yr 38 17.2 0.875 <5 AF ~18.4 ~27 18.0 0.845
1 adult F <2 AF
50F ~14F
10 *1 adult 10 yr 10.2 0.872 *<1 ~27.8 8.7 0.789
~3M ~4M
M AM
<3 AF
~25F
*<1 ~16.7 9.9 0.830
~4M
AM

Reintroduction schemes
The establishment of a new orangutan The following reintroduction scheme was
population through multi-year releases into modelled using the Bornean orangutan
unoccupied habitat is a potential strategy to model:
increase wild orangutan populations. Many
different release strategies can be used and • Year 1: 20 releases (13 females, 7 males)
may vary by the age, sex and number of • Year 2: 50 releases (34 females, 16 males)
orangutans released as well as the length and
• Year 3: 50 releases (34 females, 16 males)
schedule of release. A thorough assessment
of reintroduction schemes is beyond the • Year 4: 50 releases (34 females, 16 males)
scope of this PVA. However, a specific scheme • No further releases after Year 4
was requested to be modelled as an example.

Orangutan Population and Habitat Viability Assessment 65

 ages and approaches K, the population levels
off, with slight oscillations as the sex and
age structure adjust to reach a more stable
balance.

Viability Of Sumatran Orangutan

Populations
PVA Vortex models for Sumatran orangutan
populations were developed in collaboration
with participants at the 2004 PHVA and 2005
Figure 18. Mean population size over first Action Plan workshops using the most current
100 years of sample reintroduced Bornean field data and other expertise and resources
population (K=350). Bars indicate SD.
available at that time (Singleton et al. 2004; Ellis
et al. 2006). These models served as a basis for
Released orangutans were 8-15 years old
this PVA, with revisions to the population-specific
(except for two 18-year-old males in Year 1 to
model inputs provided by 2016 PHVA participants
provide a breeding age male in the population).
as outlined below (Table 16).
Mortality was 13-18% during the first year
of release, 3-6% during the second year,
Population-Specific Inputs
and then was the same as wild orangutans.
Initial population size (N) and carrying
Releases were made into unoccupied habitat
capacity (K): Populations were defined by
with a carrying capacity of 350. No habitat
the PHVA working groups based on GIS
loss or losses (e.g., poaching) were included.
habitat data and other information and
Model results suggest that this scheme leads were delineated to represent populations
to a viable population (PE500=0.001; N500=309; or population fragments whose members
GD500=0.951) and are similar to those for a interbreed and undergo similar threats.
starting population of 350. Although mortality Habitat modelling was used to estimate
is substantially higher during the first two current carrying capacity of spatially defined
years after release, reproduction is higher at populations. Populations were assumed to be
the initial low densities based on the density- at carrying capacity (except for reintroduced
dependent reproduction incorporated into populations, as noted) and were distributed
the model. The young age of the population across age-sex classes according to a stable
combined with a female-biased sex ratio also age distribution that is characteristic of the
promote rapid growth (high reproduction mortality and reproductive rates described for
and low mortality), allowing the population the model. Initial individuals were assumed to
to reach K in approximately 35 years. Figure be unrelated; this is a reasonable assumption
13 shows the rapid growth during years for large populations but may underestimate
1-4 (releases) and shortly thereafter due to current inbreeding levels in small isolated
reproduction for ~30 years. As the population populations if isolation is not recent.

66 Orangutan Population and Habitat Viability Assessment

 Habitat loss and fragmentation: Habitat loss is in association with logging or habitat
or alteration is a primary threat to orangutans conversion and is already incorporated into
on both Sumatra and Borneo. Future rates the model as immediate reduction in K and
of habitat loss were estimated based on past associated removal of orangutans. The PHVA
trends and anticipated future conditions. working groups estimated the annual loss of
These rates were applied to the remaining orangutans from each population based upon
habitat each year, such that the actual historical information. Losses accounted for by
area of habitat lost each year is not linear the estimated reduction in K were calculated,
but diminishes over time. Habitat changes and any additional losses above that were
were modelled as a permanent reduction in incorporated into the model as direct harvest.
carrying capacity for orangutans, which not
New migrants or releases: Most populations
only reduces K but also removes individuals
were assumed to be isolated in the model and
from the population when N>K by imposing
receive no new individuals. A few Sumatran
additional probabilistic mortality across all
populations were estimated to receive one
age-sex classes. Habitat loss was applied each
migrant every 10 or 20 years, modelled as
year for the first 100 years of the simulation
an adult male. For the two reintroduced
only.
populations, future releases were modelled
Direct loss of orangutans: Orangutans as specified by the PHVA working groups (see
are also hunted or otherwise removed Table 16).
illegally from the wild. Some of this loss

Table 16. Population-specific model inputs (initial N, initial K, % loss in K, removals, additions) and resulting
K and % lost over 100 years for eight wild and two reintroduced* Sumatran orangutan populations.

% loss in K lost in Total removals,

Population Initial N Initial K KY100 Additions
K (annual) 100 yrs all causes (annual)
West Leuser 5,920 5300 0.29 4429 25% 10M / 18F / 7inf 1M/10 yrs
Sikulaping 260 260 0.01 258 1% 0.5M / 1F / 0.5inf 1M/10 yrs
East Leuser 5,780 5780 0.33 4152 28% 11M / 20F / 9inf 1M/10 yrs
Tripa Swamp 210 210 11.48 0 100% 1M / 2F / 1inf 1M/10 yrs
Trumon-Singkil 1270 1270 0.43 825 35% 2M / 3.5F / 1.5inf 1M/10 yrs
Siranggas/BatuArdan 90 90 0.10 79 10% 0.5M / 1F / 0.5inf 1M/20 yrs
West Batang Toru 600 600 0.03 587 3% 2.45M / 0.95F / 0.5inf --
East Batang Toru 160 160 0.03 157 3% 1.25M / 0.75F / 0.5inf --
Bukit Tiga Puluh* 120 1560 1.92 224 86% -- 8/yr
Jantho landscape* 60 400 0.001 400 0% -- 20/yr
TOTAL 68% ~29M / ~47F / ~20inf

Orangutan Population and Habitat Viability Assessment 67

 Population Scenarios
Five scenarios were run for each of the eight extant orangutan populations:

• Best Estimate: projected habitat loss and/or removals (habitat loss for 100 yrs; harvest for
500 yrs)
• HarvOnly: Additional removals only (i.e., those not due to habitat loss), for 500 yrs; no
habitat loss
• HarvOnly100Y: Additional removals only, for 100 yrs and then stopped; no habitat loss
• HabitatLossOnly: Habitat loss (i.e., loss of K) for 100 yrs; no additional removals
• NoLoss: No projected loss of habitat (K) and no removals (e.g., hunting)

Comparison of these scenarios provides upon those from the Reintroduction Scheme
insight into the relative impacts of habitat discussed above. Releases started in Year 2 of
loss and direct removals as well as the ability the model and were tested for 10, 20 or 50
of the population to recover and persist if years of releases.
these threats were to be removed. Graphs are
West Leuser
presented with results of mean population
size over time for all five scenarios. Variation Projected viability: Poor
around these means is quite large, but these PE100=0.008; PE500=1; N500=0; GD500=0
mean trends are informative in determining
At projected rates of habitat loss and removals,
the drivers of population size and persistence
the West Leuser population is projected to
under the rates tested.
decline to extinction, with median time to
For the two reintroduced populations (Bukit extinction = 235 years. Much of this decline
Tiga Puluh and Jantho landscape), these is driven by the estimated harvest. If harvest
populations were supplemented with 8 (5 is stopped, the population is able to recover
female, 3 male) or 20 (13 female, 7 male) as long as it is not fragmented. If habitat
orangutans, respectively, per year (Table 16). loss is not too severe or does not cause
Animals were 9-15 years old at time of release, fragmentation, the population may stabilize
and had higher mortality rates during the first around the new K. Eliminating all habitat loss
year (13-18%) and second year (3-6%) after and other removals immediately results in a
release, then assumed ‘normal’ mortality risk. large, genetically diversity population with
These ages and mortality rates were based no risk of extinction in 500 years (PE100=0;
PE500=0; N500=5420; GD500=0.997).

68 Orangutan Population and Habitat Viability Assessment

Figure 19. Mean population size over 500 years for West Leuser, under projected best estimated future
conditions (left, with SD bars) and under all five estimated and alternate future situations (right).

Sikulaping
Projected viability: Poor PE100=0.15; PE500=1; N500=0; GD500=0

At projected rates of habitat loss and removals, relatively small size of this population and
the Sikulaping population is projected to habitat. Habitat loss is estimated to be minimal
decline to extinction, with median time to for this area. Eliminating all habitat loss and
extinction = 168 years. This decline is driven other removals results in a small, genetically
entirely by the estimated harvest. If harvest is diversity population with very little risk of
stopped, the population is able to recover to extinction in 500 years (PE100=0; PE500=0.004;
some extent, depending upon how quickly N500=206; GD500=0.954).
harvest is reduced or eliminated given the

Figure 20. Mean population size over 500 years for Sikulaping, under projected best estimated future
conditions (left, with SD bars) and under all five estimated and alternate future situations (right).

Orangutan Population and Habitat Viability Assessment 69

East Leuser
Projected viability: Poor PE100=0.004; PE500=1; N500=0; GD500=0

At projected rates of habitat loss and removals, If habitat loss is not too severe or does not
the East Leuser population is projected to cause fragmentation, the population may
decline to extinction, with median time to stabilize around the new K. Eliminating all
extinction = 202 years. Similar to West Leuser, habitat loss and other removals results in a
much of this decline is driven by the estimated large, genetically diversity population with
harvest. If harvest is stopped, the population is no risk of extinction in 500 years (PE100=0;
able to recover as long as it is not fragmented. PE500=0; N500=5364; GD500=0.997).

Figure 21. Mean population size over 500 years for East Leuser, under projected best estimated
future conditions (left, with SD bars) and under all five estimated and alternate future situations
(right).

Tripa Swamp
Projected viability: Very poor PE100=1; PE500=1; N500=0; GD500=0

The Tripa Swamp population is projected to drive the population to extinction (median
decline rapidly to extinction (median time to time to extinction = 58 years, vs 37 years for
extinction = 27 years) due to projected high habitat loss only). Eliminating all habitat loss
rates of habitat loss and harvest. Both habitat and other removals results in a small viable
loss and harvest are strong drivers of decline, population with little risk of extinction in
with habitat loss being more significant given 500 years (PE100=0; PE500=0.002; N500=164;
projected rates. In the absence of habitat loss, GD500=0.947).
direct harvest at the projected levels may also

Figure 22. Mean population size over 500 years for Tripa Swamp, under projected best estimated
future conditions (left, with SD bars) and under all five estimated and alternate future situations
(right).

70 Orangutan Population and Habitat Viability Assessment

Trumon-Singkil
Projected viability: Poor PE100=0; PE500=1; N500=0; GD500=0

At projected rates of habitat loss and If habitat loss is not too severe or does not
removals, the Trumon-Singkil population cause fragmentation, the population may
is projected to decline to extinction, with stabilize around the new K. Eliminating all
median time to extinction = 237 years. This habitat loss and other removals results in a
decline is driven by harvest and habitat loss. large, genetically diversity population with
If harvest is stopped, the population is able no risk of extinction in 500 years (PE100=0;
to recover as long as it is not fragmented. PE500=0; N500=1110; GD500=0.988).

Figure 23. Mean population size over 500 years for Trumon-Singkil, under projected best estimated
future conditions (left, with SD bars) and under all five estimated and alternate future situations
(right).
Siranggas/Batu Ardan
Projected viability: Very poor PE100=0.996; PE500=1; N500=0; GD500=0

At projected rates of habitat loss and removals, habitat, making this small population even
the Siranggas/Batu Ardan population is more vulnerable. Eliminating all habitat loss
projected to decline rapidly to extinction, and other removals results in a small, slightly
with median time to extinction = 49 years. inbred population with some long-term risk
Most of this decline is driven by the estimated of extinction if there is no supplementation
harvest. If harvest is stopped immediately, the (PE100=0; PE500=0.086; N500=50; GD500=0.881).
population still slowly declines with loss of

Figure 24. Mean population size over 500 years for Siranggas/Batu Ardan, under projected best
estimated future conditions (left, with SD bars) and under all five estimated and alternate future
situations (right).

Orangutan Population and Habitat Viability Assessment 71

West Batang Toru
Projected viability: Moderate to poor PE100=0.008; PE500=0.41; N500=225; GD500=0.964

At projected rates of habitat loss and recover as long as it is not fragmented. Habitat
removals, the West Batang Toru population loss is estimated to be minimal for this area.
is projected to decline slowly over time and Eliminating all habitat loss and other removals
has a significant risk of extinction, with mean results in a moderate size, genetically diversity
time to extinction = 310 years. This decline population with very little risk of extinction in
is driven entirely by the estimated harvest. If 500 years (PE100=0; PE500=0.002; N500=512;
harvest is stopped, the population is able to GD500=0.973).

Figure 25. Mean population size over 500 years for West Batang Toru, under projected best estimated
future conditions (left, with SD bars) and under all five estimated and alternate future situations (right).

East Batang Toru

Projected viability: Poor PE100=0.312; PE500=1; N500=0; GD500=0

At projected rates of habitat loss and

removals, the East Batang Toru population is supplementation. Habitat loss is estimated
projected to decline to extinction, with mean to be minimal for this area. Eliminating all
time to extinction = 124 years. This decline habitat loss and other removals results in a
is driven entirely by the estimated harvest. small, slightly inbred viable population with
This population is currently at ~MVP and so little risk of extinction in 500 years (PE100=0;
harvest must be reduced or stopped quickly PE500=0.014; N500=102; GD500=0.882).
to maintain viability without the need for

Figure 26. Mean population size over 500 years for East Batang Toru, under projected best estimated
future conditions (left, with SD bars) and under all five estimated and alternate future situations (right).

72 Orangutan Population and Habitat Viability Assessment

Bukit Tiga Puluh: reintroduced population
Projected viability: Good PE100=0; PE500=0.016; N500=162; GD500=0.924 (releases for 10 years)

The Bukit Tiga Puluh population is projected is driven to decline due to continuing habitat
to increase for about 50 years under all three loss, stabilizing once habitat loss stops.
release schemes, assuming no additional Population size and viability will depend upon
harvests and using the age, sex ratio and the control of habitat loss and other removals.
survival of released animals modelled. If no habitat loss occurs, the population
Additional years of release lead to faster grows to K and is a large, genetically diverse
growth to K, but only 10 years of releases population (PE100=0; PE500=0.002; N500=1394;
result in a viable population. After about 50 GD500=0.981).
years the population fills the available K and

Figure 27. Mean population size over 500 years for Bukit Tiga Puluh, under projected rates of habitat
loss at different lengths of annual releases (10, 20, 50 yrs) (left), and with no habitat loss and releases
for 10 years (right, with SD bars).

Jantho Landscape: reintroduced population

Projected viability: Good PE100=0; PE500=0; N500=323; GD500=0.956 (releases for 10 years)

The Jantho population is projected to increase

quickly and then level off close to K under all
three release schemes, assuming no habitat
loss or additional harvests and using the age,
sex ratio and survival of released animals
modelled. Additional years of release lead
to slightly faster growth, but only 10 years
of releases result in a viable population.
Population size and viability will depend upon
the control of habitat loss and other removals. Figure 28. Mean population size over 500 years for Jantho,
at different lengths of annual releases (10, 20, 50 yrs) and
assuming no habitat loss or other harvest.

Orangutan Population and Habitat Viability Assessment 73

 Forest fragmentation and loss scenarios

Alternative scenarios were modelled for and time to extinction. All scenarios for West
West Leuser, East Leuser, and Batang Leuser and East Leuser project complete
Toru to investigate the potential impact extinction within 500 years (mean times to
of forest loss and road construction. The extinction of 156-259 years). Scenarios for
only impact modelled here was population Batang Toru with 6 fragments also project
fragmentation. Other potential impacts of certain extinction. When modelled as 1-3
roads such as additional mortality were not fragments, only West Batang Toru is large and
included in these models. Habitat loss and has some probability of long-term survival (43-
removal rates from the default scenarios were 54%) as a reduced and declining population.
proportionally distributed across fragments. If all habitat loss and harvest are removed
Table 17 lists the scenario inputs (number and from these populations, most fragments are
size of fragments) along with model results. viable. Fragments under 100 animals are not
viable (WL1, EL5, Sibual-buali area of BT, and
Under the projected rates of habitat loss
West BT 1, 2 and 4), and fragments between
and other loss, none of these populations or
100-200 animals met viability criteria but are in
fragments meets the criteria for viability. In
decline (EL1, EL3, East BT, and West BT 3).
most cases, fragmentation hastens the decline

Table 17. Population size, carrying capacity, and results for road fragmentation scenarios.

Population Initial N=K KY100 PE100 PE500 N100 N500 GD100 GD500
West Leuser – 1 pop* 5922 4429 0.008 1 3641 -- 0.999 --
West Leuser – 2 pops 5922 4429 0.014 0.994 3181 -- 0.999 --
WL1 35 26 0.258 1 13 -- 0.865 --
WL2 250 187 0.038 0.998 130 -- 0.979 --
WL3 1065 797 0.044 1 567 -- 0.995 --
WL4 4020 3006 0.028 0.996 2177 -- 0.999 --
WL5 522 413 0.046 1 293 -- 0.991 --

East Leuser – 1 pop* 5779 4152 0.004 1 3276 -- 0.999 --

East Leuser – 2 pops 5779 4152 0.024 1 2655 -- 0.999 --
EL1 174 125 0.078 1 80 -- 0.969 --
EL2 1771 1273 0.044 1 819 -- 0.997 --
EL3 141 101 0.126 1 60 -- 0.973 --
EL4 562 404 0.070 1 256 -- 0.990 --
EL5 76 55 0.138 1 31 -- 0.930 --
EL6 3055 2194 0.042 1 1410 -- 0.998 --

Batang Toru – 1 pop 767 744 0.034 0.714 515 124 0.993 0.966
Batang Toru – 2 pops* 767 744 0.006 0.458 511 194 0.993 0.962
East BT 162 157 0.302 1 48 -- 0.950 --

74 Orangutan Population and Habitat Viability Assessment

 West BT 605 587 0.006 0.458 463 194 0.993 0.962
Batang Toru – 3 pops 726 704 0.014 0.566 450 141 0.991 0.956
East BT 162 157 0.336 1 42 -- 0.945 --
Sibual-buali area 31 30 0.104 1 18 -- 0.863 --
West BT (- PLTA&HPH) 533 517 0.020 0.566 391 141 0.956 0.956
Batang Toru – 6 pops 492 477 0.028 0.992 205 -- 0.977 --
East BT 140 136 0.492 1 22 -- 0.928 --
Sibual-buali area 31 30 0.346 1 12 -- 0.852 --
West BT1 (- PLTA&HPH) 61 59 0.174 1 30 -- 0.916 --
West BT2 (- PLTA&HPH) 47 46 0.246 1 21 -- 0.892 --
West BT3 (- PLTA&HPH) 157 152 0.090 0.992 92 -- 0.962 --
West BT4 (- PLTA&HPH) 56 54 0.174 1 29 -- 0.912 --

Summary of Sumatran orangutan PVA results

Model results suggest that none of the by additional releases and are not subject to
eight extant wild populations of Sumatran harvest or substantial habitat loss.
orangutans are viable in the long term under
Lower rates and shorter periods of habitat
the projected rates and periods of habitat
loss and/or harvest will lead to intermediate
loss and harvest (Figure 24). Population
levels of viability between these two
fragmentation (e.g., due to road construction)
extremes. The actual future of Sumatran
is likely to increase the rate of decline and
orangutan populations will depend to a
risk of extinction. Alternatively, if all habitat
great extent upon the future rates of habitat
loss and harvest is immediately eliminated,
loss, fragmentation and harvest, and how
then population viability is high with good
long these threats continue before they are
retention of genetic diversity (Figure 25).
reduced or eliminated.
Similarly, the two reintroduced populations
may be viable if the populations are built up

Figure 29. Probability of survival

(PS) over time for each of the
10 Sumatran sub-populations.
Only West Batang Toru and the
two reintroduced populations
show PS > 0 in 500 years.v

Orangutan Population and Habitat Viability Assessment 75

 Viability Of Bornean Orangutan Populations

The Vortex model modified for Bornean includes an estimate of fragments within each
orangutans was used as a basis to assess habitat management unit, estimated current
the viability of the three Bornean taxa: P.p. population size and carrying capacity, and
pygmaeus, P.p. morio and P.p wurmbii. projected future habitat loss and removal rate
for each habitat management unit. Five of
Pongo pygmaeus pygmaeus Populations
these populations represent fewer than 100
Detailed population-specific model inputs individuals and are below the MVP identified
were provided by 2016 PHVA participants for even the absence of threats.
this taxon as outlined below in Table 18. This

Table 18. Population-specific model inputs for eight Bornean orangutan meta-populations (P.p. pygmaeus).

Within Estimated Removal rate

Estimated
Habitat Management Unit MP carrying Habitat loss (% loss per year) (number removed
pop size
units capacity annually)
0.38% annual loss for 10
Betung Kerihun NP and 1,790
3 1,790 years (reduction of K to 1 adult per year
Protection Forest**
3421)
0.2% annual loss for 10
Batang Ai-Lanjak-Entimau 2 adults per 5
1 1,810 2,010 years (reduction of K to
Landscape years
1970)
Danau Sentarum NP and 680 0.68% annual loss for 10 1-2 adults and 1
2 680
Corridor** years (reduction of K to 633) infant per year

Klingkang Range NP and 1% annual loss for 10 years 1 adult per year
2 80 80
Sintang Utara (reduction of K to 72) for 2 years

Bungoh NP-Gunung Nyiut 1% annual loss for 10 years 1 adult per year
2 90 90
NR and Penrisen HL (reduction of K to 85) for 2 years

Pygmaeus fragmented 10% annual loss for 10 yrs

1 30 30 2-3 adults per year
North (100% loss of habitat; K=0)

Pygmaeus fragmented 10% annual loss for 10 yrs

1 10 10 2-3 adults per year
South (100% loss of habitat; K=0)

Ulu Sebuyau-Sedilu
1 30 30 None at present 1 adult per year
Landscape

**Discrepancies in the numbers provided led to the adoption in the models of the most conservative values.
Discrepancy 1. Estimates for K for Betung Kerihun NP and Protection Forest were based on estimates for
three areas (BKNP, Hutan Lindung, Corridor), with the mid-point used for the estimated K of the corridor.
Discrepancy 2. K for Danau Sentarum NP & Corridor is given as 679 in the site characteristics table and as
890 in the threats table. 679 is adopted as the conservative estimate.

76 Orangutan Population and Habitat Viability Assessment

Betung Kerihun NP and Protection Forest
Projected viability: High PE100=0; PE500=0; N500=3222; GD500=0.995

This large population is projected to undergo the available habitat and remain large and
a relatively small rate of habitat loss for 10 genetically diverse. Immediate cessation of
years only, leaving sufficient habitat for a habitat loss and harvest results in a slightly
large population. Projected harvest rate is larger population due to higher K. The viability
small and sustainable. Given these conditions, of this population may be threatened under
this population is projected to grow to higher rates of habitat loss and harvest.

Figure 30. Mean population

size over 500 years for Betung
Kerihun NP and Protection Forest,
under projected best estimated
future conditions (red) and with
no habitat loss or harvest (blue).

Batang Ai-Lanjak-Entimau Landscape

Projected viability: High PE100=0; PE500=0; N500=1841; GD500=0.992

Like Betung Kerihun, this large population is to remain large and genetically diverse.
projected to undergo a relatively small rate of Immediate cessation of habitat loss and
habitat loss for 10 years only, leaving sufficient harvest results in a slightly larger population
habitat for a large population. Projected due to slightly higher K. The viability of this
harvest rate is small and sustainable. Given population may be threatened under higher
these conditions, this population is projected rates of habitat loss and harvest.

Figure 31. Mean population size

over 500 years for Batang Ai-Lanjak-
Entimau landscape, under projected
best estimated future conditions
(red) and with no habitat loss or
harvest (blue).

Orangutan Population and Habitat Viability Assessment 77

Danau Sentarum NP and Corridor

Projected viability: High PE100=0; PE500=0.002; N500=580; GD500=0.974

This moderate sized population is projected Immediate cessation of habitat loss and harvest
to decline in the short term under projected results in a larger population (N500=624) due
rates of habitat loss and harvest that combine to higher K. The viability of this population
to remove animals at an unsustainable rate. If may be threatened under longer periods or
habitat loss is stopped while the population higher rates of habitat loss and harvest or this
is large it is eventually able to recover and population becomes fragmented.
stabilize even under a low level of harvest.

Figure 32. Mean population size

over 500 years for Danau Sentarum
and Corridor, under projected best
estimated future conditions (red) and
with no habitat loss or harvest (blue).

Klingkang Range NP and Sintang Utara

Projected viability: Moderate to poor PE100=0.001; PE500=0.272; N500=28; GD500=0.746

While this population is projected to persist

in the short term (under essentially no
harvest), its small size makes it vulnerable
to stochastic processes, resulting in smaller
size, reduced gene diversity, and moderate
risk of extinction. Projections are slightly
better with no habitat loss or removals,
but do not meet viability criteria if isolated
from other orangutan populations (PE100=0;
PE500=0.176; N500=37; GD500=0.774).
Periodic supplementation has the potential
to substantially increase viability (e.g.,
PE100=0; PE500=0.005; N500=65; GD500=0.886, Figure 33. Mean population size over 500 years for Klingkang
Range NP and Sintang Utara, under projected best estimated
with 1 adult female added every 20 years) future conditions (red), with no habitat loss or harvest (blue),
(Figure 29). and with no losses plus supplementation of one adult female
every 20 years (green).

78 Orangutan Population and Habitat Viability Assessment

Bungoh NP-Gunung Nyiut NR and Penrisen HL

Projected viability: Moderate to poor PE100=0; PE500=0.191; N500=40; GD500=0.783

Similar to the Klingkang/Sintang Utara other orangutan populations (PE100=0;

population, this population is projected to PE500=0.116; N500=52; GD500=0.807). Periodic
persist in the short term (with essentially supplementation has the potential to
no harvest) but at reduced size and gene substantially increase viability (e.g., PE100=0;
diversity and with moderate risk of extinction. PE500=0.005; N500=77; GD500=0.895, with 1
Projections with no habitat loss or removals adult female added every 20 years) (Figure
do not meet viability criteria if isolated from 30).

Figure 34. Mean population

size over 500 years for Bungoh
NP-Gunung Nyiut NR/Penrisen
HL, under projected best
estimated future conditions
(red), with no habitat loss or
harvest (blue), and with no
losses plus supplementation
of one adult female every 20
years (green).

Fragmented North Population

Projected viability: Moderate to poor PE100=1; PE500=1; N500=0; GD500=0

This very small population is projected to

undergo heavy harvest and total habitat loss
in 10 years. Even if harvest and habitat loss
were eliminated, its small size leaves it highly
vulnerable to stochastic processes, both
demographic and genetic (PE100=0.043;
PE500=0.955; N500=0.5; GD500=0.5). Periodic
supplementation has the potential to
maintain this population provided habitat
loss and harvest could be eliminated
Figure 35. Mean population size over 500 years for
(e.g., PE100=0.006; PE500=0.109; N500=20; the fragmented North pygmaeus population, under
GD500=0.837, with 1 adult female added projected best estimated future conditions (red),
with no habitat loss or harvest (blue), and with no
every 20 years) (Figure 31). losses plus supplementation of one adult female
every 20 years (green).

Orangutan Population and Habitat Viability Assessment 79

Fragmented South Population
Projected viability: Moderate to poor PE100=1; PE500=1; N500=0; GD500=0

This extremely small population is projected every 20 years improves this population
to undergo heavy harvest and total habitat fragment (PE100=0.045; PE500=0.369; N500=8;
loss in 10 years. Even if harvest and habitat GD500=0.800; see Figure 32) but may be
loss were eliminated, its very small size insufficient. Modeling of supplementation
leaves it highly vulnerable to stochastic rates in this PVA suggest that a
processes, both demographic and genetic supplementation rate of one female every
(PE100=0.219; PE500=1; N500=0; GD500=0). 10-12 years, plus the potential addition of
Periodic supplementation has the potential an adult male if all breeding males disappear
to maintain this population provided habitat from the population, may be needed to
loss and harvest could be eliminated. For produce a long-term viable population.
example, the addition of one adult female

Figure 36. Mean population size over 500 years

for the fragmented South pygmaeus population,
under projected best estimated future conditions
(red), with no habitat loss or harvest (blue), and
with no losses plus supplementation of one
adult female every 20 years (green).

Ulu Sebuyau-Sedilu Landscape

Projected viability: Moderate to poor PE100=1; PE500=1; N500=0; GD500=0

While no habitat loss is projected at this time

for this very small population, the harvest of
one adult per year (>3%) is unsustainable. Even
if harvest were eliminated, its small size leaves
it highly vulnerable to stochastic processes,
both demographic and genetic (PE100=0.021;
PE500=0.955; N500=0.5; GD500=0.48). Periodic
supplementation has the potential to
maintain this population provided harvest and
habitat loss are eliminated (e.g., PE100=0.003;
Figure 37. Mean population size over 500 years for the
PE500=0.078; N500=22; GD500=0.836, with 1 Ulu Sebuyau-Sedilu landscape population, under projected
best estimated future conditions (red), with no habitat loss
adult female added every 20 years) (Figure or harvest (blue), and with no losses plus supplementation
33). of one adult female every 20 years (green).

80 Orangutan Population and Habitat Viability Assessment

Summary of Pongo pygmaeus pygmaeus Population Viability

Two large P.p. pygmaeus meta-populations populations were substantially less complete
(Betung Kerihun NP and Protection Forest, than for P.p. pygmaeus. There are many
and Batang Ai-Lanjak-Entimau Landscape) are data gaps with respect to estimated carrying
projected to undergo small amounts of short- capacity and threats. In addition, population
term habitat loss and relatively low levels of size estimates derived from GIS analysis do
harvest. These two meta-population have not correspond well with those estimated
high viability under the conditions modelled from survey data. For some of the specified
and are projected to maintain about 3,500 sites we were unable to locate the equivalent
orangutans combined. The smaller population GIS polygon and so comparisons could
at Danau Sentarum NP is projected to have not be made. These data gaps meant that
higher rates of short-term habitat loss and population-specific PVA models could not be
higher relative harvest rates, but if habitat developed for P.p. morio.
loss ceases as projected this population may
stabilize at 500-600 orangutans. Protection However, the PVA results for Bornean
of these large populations and their habitat populations in general as well as those for P.p.
will be critical for the persistence of this taxon pygmaeus provide a useful guide to the range
on Borneo. of viability of P.p. morio populations under
various conditions. Table 24. outlines the 17
None of the five remaining small fragments identified meta-populations for this taxon
meets the viability criterion if they remain along with estimates of current population
isolated, even if all threats are removed. size (from the PHVA and from GIS), carrying
Periodic supplementation through natural capacity, population trend, and relative
or managed translocations or releases will intensity of habitat loss and removals, all
be necessary to maintain long-term viability based on the working group’s report. The PVA
of these fragments. The required rate of results from other Bornean orangutan models
releases will vary with population size, outlined in this report were used to develop
threats, and stochastic events, but in most some general viability assessments for these
cases should be relatively infrequent. The meta-populations under various scenarios
three smallest fragments are not viable under (no future threats, with habitat loss, with
current projected high rates of habitat loss removals). High to good long-term viability is
and/or harvest; these threats would need to colored in green, moderate viability in yellow,
be addressed in these small populations in and low to poor viability in orange.
addition to periodic supplementation if they
are to persist. Summary of Pongo pygmaeus morio
Population Viability
Pongo pygmaeus morio Populations
Specific population viability estimates cannot
Data estimates compiled by the 2016 be developed for P.p.morio, as detailed
PHVA workshop participants for P.p. morio estimates of threats (habitat loss and

Orangutan Population and Habitat Viability Assessment 81

fragmentation, removal of orangutans) are not under threat, possibly representing another
available. Based on the available information, ~1,000 orangutans. Trus Madi landscape may
there are 6 large meta-populations that are be at risk depending upon the level of habitat
likely to show long-term viability as long as conversion, while Sangkulirang appears to be
any loss of habitat or orangutans remains low at risk due to both habitat loss and harvest.
and/or short term (Kutai, Tabin, Central Forest,
Seven meta-populations are small (most
Lower Kinabatangan, North Kinabatangan,
under 100 individuals) and subject to some
Ulu Kalumpang). These meta-populations,
extinction risk even in the absence of threats.
many of which are in Sabah in protected
All of these populations appear to be under
areas, represent the core populations for
risk of continued threat, resulting in poor
this taxon and could potentially combine to
long-term viability. Depending upon their
total ~11,730 (SD ±1,560) orangutans (see
specific situation, these small populations
Appendix IV for details). Wehea landscape
may be able to maintain good viability with
represents a moderate-sized meta-population
periodic supplementation if current threats
that may be vulnerable depending upon the
can be significantly reduced or eliminated.
level of habitat loss and removals that impact
it.
These viability assessments for P.p. morio
populations are meant to serve as a guide
There are 7 meta-populations of ~300
only. As more information becomes available
orangutans each; populations of this size may
on the size, available habitat, fragmentation
be viable in the absence of threats but are
and threats of P.p. morio populations, the
vulnerable to loss of habitat and individuals.
viability estimates for this taxon can be revised.
Four of these (Crocker Range, Lingkabau,
Bonggaya, Sepilok) appear to be stable and not

82 Orangutan Population and Habitat Viability Assessment

 Table 19. Estimates of current N, K, population trend, threats, and relative viability for 17 Bornean orangutan meta-populations (P.p. morio).

Popu- Habitat
#MP Est. N Est. K Removal Viability w/ no habitat Relative viability with Relative viability with
Meta-population GIS ID lation loss inten-
units Wksp (GIS) Wksp intensity loss or removal habitat loss removals
trend sity
30# Not Poor viability without Poor; cannot withstand Poor; cannot withstand
Beratus Landscape 1 - High Medium
found Declining releases loss of K harvest
Sungai Wain Land- Not Poor viability without Poor; cannot withstand Poor; cannot withstand
1 20 20* High --
scape found Declining releases loss of K harvest
Kutai NP-Bontang Variable
Not Low to High viability (if not Good viability if K Good viability if annual
Landscape 7 1,700 1,700 declin- High
found to medium fragmented) remains >500 removal <1%
ing
Belayan-Senyiur Not Moderate viability (if Moderate if K remains Low viability if harvest-
3 220 220 Medium Medium
Landscape found Declining not fragmented) >200 ed
KAL
14,
Wehea-Lessan PF 620 Mostly Good viability (if not Good viability if K Good if annual removal
4 670 15 Medium Low
Landscape (1909+2094) declining fragmented) remains >500 <0.5%
and
16
Sangkulirang Land- 310 Moderate viability (if Moderate if K remains Moderate if annual
4 310 KAL 2 Declining High Variable
scape (775) not fragmented) >200 removal <0.5%
Tabin Range Land- 1,250 High viability (if not Good viability if K Good viability if annual
2 2150 SAB 6 Stable -- --
scape (2,207) fragmented) remains >500 removal <1%
Central Forest 5,320 to High in High viability (if not Good viability if K Good viability if annual
3 6,900 SAB 7 Stable --
Range Landscape (4,765) declining areas fragmented) remains >500 removal <1%
Lower Kinabatan- 1,500 to High in High viability (if not Good viability if K Good viability if annual
gan Range Land- 2 1,500 SAB 5 Stable --
(1,082) declining areas fragmented) remains >500 removal <1%
scape
North Kinabatan- 2,030 3,000 High viability (if not Good viability if K Good viability if annual
gan Range Land- 1 SAB 4 Stable Medium --
(979) fragmented) remains >500 removal <1%
scape
Ulu Kalumpang 600 800 Good viability (if not Good viability if K Good if annual removal
1 SAB 8 Declining High --
Range Landscape (226) fragmented) remains >500 <0.5%
Crocker Range 180 Moderate viability (if Moderate if K remains May reduce viability
1 300 SAB 2 Stable -- --
Landscape (106) not fragmented) >200 until N nears K
Lingkabau Land- 150 300 Moderate viability (if Moderate if K remains May reduce viability
2 SAB 1 Stable -- --
scape (107) not fragmented) >200 until N nears K
Bonggaya Land- 190 Moderate viability (if Moderate if K remains May reduce viability
2 300 SAB 9 Stable -- --
scape (104) not fragmented) >200 until N nears K

Orangutan Population and Habitat Viability Assessment

Ulu Tungud Land- 30 SAB Low viability without Poor; cannot withstand Poor; cannot withstand
1 80 Declining High --
scape (285) 10 releases loss of K harvest
Trus madi Land- 280 SAB Moderate viability (if Moderate if K remains May reduce viability
1 350 Declining High --

83
scape (111) 11 not fragmented) >200 until N nears K
Sepilok Landscape Not Moderate viability (if Moderate if K remains Moderate if annual
1 200 300 -- --
found Stable not fragmented) >200 removal <0.5%
P.p. wurmbii Population Viability
Sixteen primary meta-populations were loss or removals, all meta-populations (except
identified for this taxon based on data for those few < 300 orangutans) are viable
compiled by the 2016 PHVA workshop and stable, with high genetic diversity and
participants at or subsequent to the workshop no risk of extinction within 100 years (Table
(see P.p. wurmbii working group report). 20). In contrast, the long-term viability of
Data availability was intermediate between most meta-populations is moderate to poor
that available for P.p. pygmaeus and for under current estimated rates of habitat
P.p.morio, with general estimates provided loss and removals. While most have no risk
for population size and threats. The data of extinction within 100 years, these meta-
provided in Table 20 were used to develop a populations are projected to decline by 60-
general PVA model for each meta-population 90%, reducing their size such that they may
to provide a relative viability assessment for become vulnerable to stochastic threats and
each. This information is subject to revisions at risk. Only the three large meta-populations
that may alter these viability assessments; (Tanjung Puting, Sebangau, Arabela
thus, they should be used only as guides for Schwaner) remain large after 100 years given
relative viability comparisons. projected threat levels.

The following assumptions were made for

these models, based on those used in other PVA
models in this report: 1) each meta-population
was modelled as a single population with
complete connectivity among sub-populations
and fragments within the meta-population;
2) meta-populations are at carrying capacity
for their current habitat; 3) % habitat loss was
applied to the K current in that year, meaning
that the actual area lost diminishes each year
over time; and 4) removals are applied as the
% of adults removed each year, proportional Figure 38. Mean population size over 100 years for the Kubu
Raya meta-population, under estimated threat conditions (red
across sex. Estimates that include < or > were for lower estimated N, purple for upper estimated N), and
with no habitat loss or harvest (blue for lower estimated N,
increased or decreased by 0.1% (e.g., < 2% green for upper estimated N). Bars indicate + 1 SD.
= 1.9%; > 2% = 2.1%). Four scenarios were
run for each meta-population, using lower Note that projected rate of decline tapers
or upper population estimates, and with or over time, as habitat loss and removals are
without threats (habitat loss and removals). modelled as being proportional to density. If
All scenarios were run for 100 years only the area of habitat lost and/or the number of
orangutans removed remains constant each
The results follow a similar pattern for each
year, these meta-populations (and the taxon)
of the 16 meta-populations, as illustrated
will decline to extinction within 100 years
by Figure 38. for the Kubu Raya meta-
population. In the absence of further habitat

84 Orangutan Population and Habitat Viability Assessment

 Table 20. Estimates of current N, population trend, threats, and relative viability for 16
Bornean orangutan meta-populations (P.p. wurmbii) over 100 years.

Within Population Habitat loss Removal Viability with no threats

Meta-population Est N Viability with est. threats (100 yrs)
MP units trend intensity intensity (100 yrs)
Kubu Raya 3 +frag- 1,240 Declining High (2%) Medium ~86% decline; PE100=0 Good viability
ments (1-2%) N100 = 111-235 Stable near K
Gunung Palung 3 +frag- 3,280 Stable/ Medium to Medium to ~86% decline; PE100=0 High viability
-Sg Putri ments declining high (2%) low (~1%) N100 = 375-562 Stable near K
Pematang Ga- 4 +frag- 630 Declining High (2%) Medium ~86% decline; PE100=0 Good viability
dung ments (2%) N100 = 68-107 Stable near K
Sungai Tengar 3 +frag- 160 Declining High (2%) High (>2%) ~88% decline; PE100 =0.002-0.026 Moderate viability
ments N100 = 11-27; G100 = 0.88-0.94 Stable near K
Kendawan- 3 +frag- 50 Declining High (2%) High (>2%) >90% decline; PE100 =0.30-0.86 Poor viability
gan-Jelai ments N100 = 1-7; G100 = 0.68-0.81 Slow decline; PE100 < 0.038
Lamandau-Suku- 2 +frag- 630 Stable High (2%) Low (<1%) ~86% decline; PE100=0 Good viability
mara ments N100 = 73-106 Stable near K
Kotawaringin 4 +frag- 640 Declining High (2%) Low (<1%) ~86% decline; PE100=0 Good viability
Lama ments N100 = 60-119 Stable near K
Tanjung Putin 1 +frag- 4,180 Stable Variable -- ~61% decline; PE100=0 High viability
ments (1%) N100 = 1441-1800 Stable near K
Seruyan-Sampit Fragments 120 Declining High (2%) Medium ~88% decline; PE100 =0.004-0.06 Poor to moderate viability
(1-2%) N100 = 9-22; G100 = 0.85-0.93 Small decline; PE100 < 0.006
Katingan 3 +frag- 4,020 Declining High (2%) -- ~86% decline; PE100=0 High viability
ments N100 = 472-663 Stable near K
Sebangau 2 +frag- 6,080 Stable Variable -- ~61% decline; PE100=0 High viability
ments (1%) N100 = 2272-2417 Stable near K
Rungan River 2 +frag- 2,260 Declining Variable -- ~86% decline; PE100=0 High viability
Landscape ments (2%) N100 = 247-401 Stable near K
Kahayan-Kapuas 6 +frag- 1,680 Declining Variable -- ~86% decline; PE100=0 High viability
ments (2%) N100 = 151-331 Stable near K
Kapuas-Barito 3 +frag- 2,550 Declining High (2%) Medium ~86% decline; PE100=0 High viability
(Mawas) ments (1-2%) N100 = 2281-434 Stable near K
Barito Timur 3 230 Declining High (2%) Medium ~87% decline; PE100=0 to 0.008 Moderate viability
(1-2%) N100 = 18-41; GD100 = 0.92-0.96 Stable near K
Siawan-Belida 0 0 0 -- -- Not assessed (no orangutans pres- --

Orangutan Population and Habitat Viability Assessment

ent)
Arabela Schwan- 6 +frag- 10,450 Stable Medium to Low (<1%) ~59% decline; PE100=0 High viability
er ments low (<2%) N100 = 3479-5133 Stable near K

85
TOTAL 38,200
Summary of P.p. wurmbii Population Viability viable in the long term under the projected
The three large, stable meta-populations rates and periods of habitat loss and harvest.
(Tanjung Puting, Sebangau, Arabela Schwaner) The two reintroduced populations may be
are likely to be viable over time, provided that viable with additional releases provided they
habitat loss does not significantly reduce K or are not subject to harvest or substantial habitat
fragment the population and that removals loss. If all habitat loss and harvest were to
are low. These meta-populations could total be immediately eliminated, then population
~17,000 to 22,000 orangutans if carrying viability would be high for Sumatran
capacity (habitat) is not lost and orangutans orangutans. Lower rates and shorter periods
are not extracted or killed. Estimated current of habitat loss and/or harvest will lead to
habitat loss and removal rates for these meta- intermediate levels of viability between these
populations, while low, would result in ~60% two extremes.
reduction in orangutan numbers in these
Bornean populations are divided into three
areas over 100 years. Several moderately large
taxa; all three have large, potentially viable
populations have combined threat levels that
meta-populations, moderate-sized meta-
lead to severe decline (~86%) if allowed to
populations at various degrees of risk, and small
continue; while declining, these populations
populations under threat with low viability
may exhibit good viability IF habitat loss and
without threat abatement and/or periodic
removals can be slowed or halted while the
supplementation. The least numerous of the
populations are still large and not fragmented.
three is P.p. pygmaeus, with two large meta-
Almost all meta-populations may be viable if
populations totalling ~5000 orangutans that
habitat loss and removal of orangutans were
have good long-term viability under projected
halted immediately.
conditions, while other meta-populations are
Summary Of PVA Modelling at risk due to threats and/or small population
Results size. P.p. morio has six large meta-populations
This PVA was developed in concert with the totaling ~16,000 orangutans that have good
2016 PHVA workshop for orangutans and is viability provided habitat loss and removals
based upon the best available information remain low and/or are eliminated. Several
at that time. The following questions were moderate-size meta-populations also may
addressed by this PVA; brief conclusions are be viable if losses remain negligible, while
given below. small populations under threat are at risk of
extinction. The three large P.p. wurmbii meta-
What is the projected viability of current populations totaling ~20,000 orangutans,
orangutan populations given the best plus several moderate-size meta-populations,
estimates of population size, threats and have good viability if habitat loss can be
management? controlled. Several smaller meta-populations
are at risk due to high removal rates as well as
None of the eight extant wild populations
habitat loss and small size.
of Sumatran orangutans are projected to be

86 Orangutan Population and Habitat Viability Assessment

What is the projected impact on orangutans of What is the smallest current population that
the construction of roads through orangutan could meet the MVP standard if allowed
habitat (e.g., in West and East Leuser, in West space to grow larger (e.g., reintroductions
and East Batang Toru)? into a new area, additional habitat added to
an existing area)?
PVA results for road fragmentation scenarios
are conservative estimates of road impacts, as Populations of at least 50 orangutans are
they do not consider additional mortality or able to meet the MVP standard if they have
increased accessibility. Fragmentation hastens sufficient space to grow, provided they are not
decline and time to extinction and in most under threat of habitat loss, fragmentation
scenarios led to eventual extinction under or harvest. These results are based on the
current projected threats. In the absence of current PVA model, which incorporates
habitat loss, removals or additional mortality, density-dependent reproduction and thus
fragmentation alone did not greatly impact allows populations to grow at a faster rate at
viability. low density.

What is the smallest population size that can What level of periodic supplementation
meet the agreed standards for a Minimum would be needed to maintain the viability of
Viable Population (MVP)? How does this size small populations below the MVP?
change with different conditions or threat
Orangutan populations of 50 or fewer
levels?
animals can be maintained through
The PHVA participants defined a viable periodic supplementation. The required
population as one with < 1% probability of supplementation rate will depend upon the
extinction in 100 years and < 10% risk of population size and potentially other factors
extinction in 500 years. Using this definition, such as threat levels. PVA results suggest that
the MVP for Sumatran orangutans is 150 and the addition of one young adult female every
MVP=100 for Bornean orangutans. Although ~35 years can provide viability to a population
defined as ‘viable’, these populations of of 50, while a population of 20 may need
100-150 demonstrate a slow declining trend supplementation with one adult female every
and reduced gene diversity (i.e., inbreeding 13 years. Very small fragments may be at risk
accumulation). A minimum population of of losing their sole breeding male and may
200 orangutans is needed for both species to require addition of an adult male in some
retain 90% GD for 500 years, and at least 500 cases.
orangutans are needed to stabilize population
size and avoid decline. All of these thresholds
are higher if the initial animals are related or
subject to increased threats.

Orangutan Population and Habitat Viability Assessment 87

What is the viability of populations established
using a specified reintroduction scheme?

Release strategies may vary by the age, sex

and number of orangutans released as
well as the length and schedule of release.
A thorough assessment of reintroduction
schemes is beyond the scope of this PVA.
However, a specific scheme was modelled
that involved four consecutive years of a
large number of releases into a large area of
unoccupied habitat. Releases were of sub-
adult and young adults and were female
biased. The combination of a young, female-
biased population at low density promotes
faster growth and overall population viability.

88 Orangutan Population and Habitat Viability Assessment

 Summary

This PVA was developed to provide guidance on those factors most affecting wild
orangutan population viability, regardless of the exact definition of viability used.
This long-lived, slow reproducing species is vulnerable to factors affecting female
reproduction and survival and to the stochastic effects of small population size. Threats
that reduce population size and/or remove adult females from the population, such as
habitat loss and fragmentation as well as direct killing or removal of orangutans from
the wild, can greatly impact viability. The slow intrinsic rate of growth for this species
means that relatively small rates of continual loss (<1%) may be unsustainable. On
the other hand, low rates of periodic supplementation, especially of females, can
lead to substantial increases in viability. These conclusions may serve as a guide when
considering management and conservation strategies for this species.
c Muhammad Khair

Orangutan Population and Habitat Viability Assessment 89

90 Orangutan Population and Habitat Viability Assessment
 Orangutan GIS models

Contributors: Truly Santika, Maria Voigt, Serge Wich

Introduction (elevation, carbon content, forest-cover,

In past PHVAs the PVA models relied on expert rainfall, rainfall-variability, temperature and

opinion for orangutan population and threat temperature range) and to build a predictive

estimates, derived from local surveys. The density distribution model for the Sumatran

results, however, are often biased towards orangutan geographic range. Details are

survey areas and are not methodologically provided in Wich et al., (2016).

consistent. Using a combination of surveys

The model for Borneo is based on several types
across the known orangutan range
of data: (a) nest count data obtained from
and information about the habitat and
line transect (ground and aerial) surveys, (b)
anthropogenic threats, spatial models can
presence-absence data from line transect and
produce density maps that allow to fill the
reconnaissance walk surveys (mainly nests),
spatio-temporal gaps in survey-coverage
and (c) presence-absence data of orangutan
and to have a consistent estimate across the
sightings from interviews. It is a hierarchical
whole range.
model that separates between the latent

Approach orangutan population status and the observed

data to predict the density of orangutan on
The models for Sumatra are based on nest-
Borneo. The model estimated the orangutan
survey data that was collected across the
survival rates and colonization rates, and they
species’ range. A generalized linear modelling
were parameterized based on site-specific
approach was used to analyse the combined
information such as altitude, monthly rainfall
influence of different habitat predictors
during the dry and wet season, proportion of
c Arif Rifqi

Orangutan Population and Habitat Viability Assessment 91

 Muslims, forest extent, distance to recently were sampled, areas with known orangutan
converted forest to industrial agriculture and populations were delimited by experts and
distance to protected areas. The model also the model results limited to these areas. For
takes into account large rivers as barrier to the orangutan populations in Sumatra, this
orangutan dispersal. was done in the publication by Wich et al.,
2016 and for Borneo, this was done at the
Because the reliability of model results
PHVA 2016.
decreases with the distance to areas that

Current orangutan numbers for Borneo

The estimated change in orangutan abundance in three time periods between 1997 and
2015 are shown in table below.

Table 21. Estimated number of individuals by region.

Estimated number of individuals per time period Overall

Region 1997-2002 2003-2008 2009-2014 %
Individuals %† Individuals %† Individuals %†
Sabah 14,354 14.1% 12,638 14.9% 10,691 15.1% 14.7%
Sarawak 2,268 2.2% 1,800 2.1% 1,664 2.4% 2.2%
West Kali-
27,291 26.9% 22,103 26.0% 17,663 25.0% 26.0%
mantan
Central Kali-
49,467 48.7% 41,542 49.0% 34,673 49.0% 48.9%
mantan
East Kali-
7,294 7.2% 6,023 7.1% 5,335 7.5% 7.3%
mantan
North
815 0.8% 746 0.9% 665 0.9% 0.9%
Kalimantan
Total 101,489 100.0% 84,852 100.0% 70,691 100.0% 100.0%

† Over total number of individuals per period (in bold).

Insights
Orangutan populations on Borneo have orangutan populations in areas most suitable
declined at a rate of >25% over the last 10 for human activities has led to an enhanced
years. Pressure on orangutan populations in risk of human-wildlife conflicts. Unless threats
the same period of time varied substantially from climate change, land use change and
among regions, with the populations in other anthropogenic pressure are abated,
Sabah, Sarawak, East and North Kalimantan we predict that most remaining populations
experiencing a relatively moderate pressure, of the Bornean orangutan will be severely
as opposed to high pressure in West and impacted by human activities.
Central Kalimantan. The occurrence of

92 Orangutan Population and Habitat Viability Assessment

Poor connectivity among orangutan habitats long-term persistence of the species. This
within the boundaries of PAs is currently includes (1) maintaining high forest cover
the predominant threat to orangutan in orangutan habitats and improving the
populations in Sabah. In Sarawak, East and connectivity among the remaining habitat
North Kalimantan, habitat loss from forest patches through better spatial planning for
conversion to industrial agriculture and all regions of Borneo, (2) close cooperation
human-orangutan conflicts are the main with plantation companies, smallholder
threats. Orangutan populations in West and farmers and wider communities in managing
Central Kalimantan, are mainly endangered by conflicts with orangutans in Kalimantan, and
habitat loss from continuing forest conversion specifically in West and Central Kalimantan.
to industrial agriculture, human-orangutan This includes (3) improving the effectiveness
conflicts, and anthropogenic activities. of anti-hunting efforts and education and
(4) developing a better understanding of the
As the populations in different regions
underlying socio-economic motivations of
face different threats, specific abatement
hunting.
plans should be implemented to ensure the

Estimated yearly deforestation rates for use as threat estimates

for the PVA models
The forest area available for each population
in the year 2000 was extracted from a land
cover layer (Miettinen et al., 2012), using the
expert-delineated population polygons and a 2
km buffer around them. From the land cover-
classes only mangrove forest, peat swamp
forest, lowland forest and lower montane
forest were considered suitable orangutan
habitat. The yearly deforestation in 2000 until
2014 was obtained from the tree-loss layer
by Hansen et al., 2013. The deforestation
that occurred outside of primary forest was
excluded and for each year the amount of
remaining forest was used to calculate the
percent of habitat available lost annually, for
each population.

Orangutan Population and Habitat Viability Assessment 93

References
Alkema, S. W. T. An Orangutan (Pongo pygmae- 850–53. Data available on-line from:
us) Population Survey in Lesan River Pro- http://earthenginepartners.appspot.com/
tection Forest, East Kalimantan, Indonesia. science-2013-global-forest.
Operasi Wallacea Terpadu (2015). Husson, S. J., Wich, S. A., Marshall, A. J., Dennis,
Ancrenaz, M., Gumal, M., Marshall, A.J., Mei- R.D., Ancrenaz, M. et al. 2009. Orang-
jaard, E., Wich, S.A. & Husson, S. utan distribution, density, abundance
(2016). Pongo pygmaeus. The IUCN and impacts of disturbance. In Orang-
Red List of Threatened Species 2016: utans: Geographic Variation in Behavioral
e.T17975A17966347. http://dx.doi. Ecology and Conservation, eds. S. A.
org/10.2305/IUCN.UK.2016 1.RLTS. Wich, S. S. Utami Atmoko, T. Mitra Setia
T17975A17966347.en. Downloaded on and C. P. van Schaik. Oxford, UK: Oxford
25 February 2017. University Press, pp. 77-96.
Cattau, M., Husson, S., and S. Cheyne 2015. Husson, S.J., Morrogh-Bernard, H.Santiano,
Population status of the Bornean orang- Purwanto, A., Harsanto, F., McLardy, C.,
utan Pongo pygmaeus in a vanishing and L D’Arcy. 2015. Status of apes: Long-
forest in Indonesia: The former Mega term temporal trends in ape populations
Rice Project. Oryx, 49(3), 473-480. in 4 case studies: Bornean orangutans
Ellis, S., I. Singleton, N. Andayani, K. Traylor-Hol- in the Sabangau peat-swamp forest. In:
zer, and J. Supriatna (eds.). 2006. Suma- State of the Apes: Industrial Agriculture
tran Orangutan Conservation Action and Ape Conservation, Arcus Founda-
Plan. Washington, DC and Jakarta, tion.
Indonesia: Conservation International. Johnson A.E., Knott C.D., Pamungkas B., Pasari-
Frankham, R., Ballou, J.D. and D.A. Briscoe bu M., and Marshall A.J. 2005 A survey
(2002). Introduction to Conservation of the orangutan (Pongo pygmaeus
Genetics. Cambridge Univ. Press. pygmaeus) population in and around
Gaveau, D.L.A., S. Sloan, E. Molidena, H. Yaen, Gunung Palung National Park, West Kali-
D. Sheil, N.K. Abram, M. Ancrenaz, R. mantan, Indonesia based on nest counts.
Nasi, M. Quinones, N. Wielaard, and E. Biological Conservation.
Meijaard. 2014. Four decades of forest Lacy, R.C. 2000. Structure of the VORTEX simula-
persistence, loss and logging on Borneo. tion model for population viability analy-
Plos One 9 (7): e 101654. sis. Ecological Bulletins 48:191-203.
Gilpin, M.E. and M.E. Soulé. 1986. Minimum Lacy, R.C., P.S. Miller, and K. Traylor-Holzer. 2017.
viable populations: processes of species VORTEX: A Stochastic Simulation of the
extinction. Pp. 19-34 in M. Soule (ed.). Extinction Process. Version 10 User’s
Conservation Biology: The Science of Manual. Apple Valley, MN: IUCN SSC
Scarcity and Diversity. Sinauer Associates: Conservation Breeding Specialist Group
Sunderland, MA. and Chicago Zoological Society.
Hansen, M. C., P. V. Potapov, R. Moore, M. Lacy, R.C. and J.P. Pollak. 2017. VORTEX: A
Hancher, S. A. Turubanova, A. Tyukavina, Stochastic Simulation of the Extinction
D. Thau, S. V. Stehman, S. J. Goetz, T. R. Process. Version 10.2.6. Chicago Zoologi-
Loveland, A. Kommareddy, A. Egorov, L. cal Society, Brookfield, IL.
Chini, C. O. Justice, and J. R. G. Town- MacPhee, R. D. E. and A. D. Greenwood 2013.
shend. 2013. “High-Resolution Global “Infectious Disease, Endangerment,
Maps of 21st-Century Forest Cover and Extinction,” International Journal of
Change.” Science 342 (15 November): Evolutionary Biology, vol. 2013, Article ID
571939. doi:10.1155/2013/571939

94 Orangutan Population and Habitat Viability Assessment

Marshal AJ, LA Salas, S Stephens, Nardiyono,L structing the demographic history of
Engstrom, E Meijard and SA Stanley. Use orang-utans using Approximate Bayesian
Limestone Forests by Bornean Orang- Computation. Mol Ecol 24, 310-327.
utans(Pongo pygmaeus morio) in the O’Grady, J.J., B.W. Brook, D.H. Reed, J.D. Ballou,
Sangkulirang Peninsula, East Kalimantan, D.W. Tonkyn, and R. Frankham. 2006.
Indonesia. American Journal of Primatol- Realistic levels of inbreeding depression
ogy 69:1–8 (2007) strongly affect extinction risk in wild
Mathewson PD, SN Spehar, E Meijaard, Nardiy- populations. Biological Conservation
ono, Purnomo, A Sasmirul, Sudiyanto, 133:42-51.
Oman, Sulhnudin, Jasary, Jumali and AJ Rijksen, H. D., and E. Meijaard. 1999. Our
Marshall. Evaluating Orangutan Cesus vanishing relative. The status of wild
Techniques Using Nest Decay Rates: orang-utans at the close of the twentieth
Implication for Population Estimates. century. Kluwer Academic Publishers,
Ecological Applications, 18(1), 2008, pp. Dordrecht, The Netherlands.
208–221
Shaffer, M. 1987. Minimum viable populations:
McCallum H. Disease and the dynamics of ex- coping with uncertainty. Pp. 69-86 in M.
tinction 2012. Philosophical Transactions Soule (ed.). Viable Populations for Con-
of the Royal Society B: Biological Scienc- servation. Cambridge University Press:
es.367(1604):2828-2839. doi:10.1098/ Cambridge.
rstb.2012.0224.
Soule, M., M. Gilpin, W. Conway, and T. Foose.
Meijaard, E., Welsh, A., Ancrenaz, M., Wich, 1986. The millenium ark: how long a
S., Nijman, V., and A.J. Marshall. 2010. voyage, how many staterooms, how
Declining orangutan encounter rates many passengers? Zoo Biology 5: 101-
from Wallace to the present suggest the 113.
species was once more abundant. PloS
Singleton, I., S. Wich, S. Husson, S. Stephens, S.
ONE, 5(8).
Utami Atmoko, M. Leighton, N. Rosen,
Meijaard E., Buchori D., Hadiprakarsa Y., Ancren- K. Traylor- Holzer, R. Lacy and O. Byers
az. M., et al. 2011. Quantifying Killing (eds.). 2004. Orangutan Population
of Orangutans and Human-Orangutan and Habitat Viability Assessment: Final
Conflict in Kalimantan, Indonesia. PLoS Report. IUCN/SSC Conservation Breeding
ONE, 6 (11) Specialist Group, Apple Valley, MN.
Miettinen, J., Shi C., Tan W.J. and Liew S.C. 2012. Singleton, I., Wich, S.A., Nowak, M. & Ush-
2010 land cover map of insular South- er, G. (2016). Pongo abelii. (errata
east Asia in 250m spatial resolution. version published in 2016) The IUCN
Remote Sensing Letters 3: 11-20. DOI: Red List of Threatened Species 2016:
10.1080/01431161.2010.526971 e.T39780A102329901. Downloaded on
Morrogh-Bernard H., Husson S., Page S.E., and 25 February 2017.
Rieley J.O. 2003 Population status of the Spehar, S. N., Loken, B., Rayadin, Y. & Royle, J.
Bornean orang-utan (Pongo pygmaeus) A. Comparing spatial capture–recapture
in the Sebangau peat swamp forest, modeling and nest count methods to es-
Central Kalimantan, Indonesia. Biol Cons timate orangutan densities in the Wehea
110:141-152. Forest, East Kalimantan, Indonesia. Biol.
Nater A, Greminger MP, Arora N, van Schaik CP, Conserv. 191, 185–193 (2015).
Goossens B, Singleton I, Verschoor EJ,
Warren KS, Krützen M (2015) Recon-

Orangutan Population and Habitat Viability Assessment 95

Tilson, R., U.S. Seal, K. Soemarna, W. Ramono,
E. Sumarjda, S. Poniran, C. van Schaik,
M. Leighton, H. Rijksen, A. Eudey (eds).
1993. Orangutan Population and Habitat
Viability Analysis Report. IUCN/SSC
Captive Breeding Specialist Group, Apple
Valley, MN.
Wich, S.A., S.S. Utami-Atmoko, T.M. Setia, H.D.
Rijksen, C. Schürmann, J.A. van Hooff,
and C.P. van Schaik. 2004. Life history of
wild Sumatran orangutans (Pongo abelii).
J. Hum. Evol. 47(6): 385-398.
Wich, S.A., Meijaard, E., Marshall A.E., Husson,
S., Ancrenaz, M. et al. 2008. Distribution
and conservation status of the orangutan
(Pongo spp.) on Borneo and Sumatra:
how many remain? Oryx, 42 (3): 1-11.
Wich, S.A., Riswan, Jenson, J., Refisch, J., Nelle-
mann, C. (2011). Orangutans and the
economics of sustainable forest man-
agement in Sumatra. Indonesia: UNEP/
GRASP/PanEco/YEL/ICRAF/GRID-Arendal.
Wich, S.A., Gaveau, D., Abram, N., Ancrenaz, M.,
Baccini, A., et al. 2012. Understanding
the Impacts of Land-Use Policies on a
Threatened Species: Is There a Future for
the Bornean Orangutan? PLoS ONE 7(11)
Wich, S. A., Singleton, I., Nowak, M. G., Atmoko,
S. S. U., Nisam, G., Arif, S. M. and
Gaveau, D. L. 2016. Land-cover changes
predict steep declines for the Sumatran
orangutan (Pongo abelii). Science ad-
vances, 2(3), e1500789.

96 Orangutan Population and Habitat Viability Assessment

 Appendix I
Gathering Information

Considering the limited data collection for trainings to present on orangutan survey
Kalimantan in PHVA 2004, FORINA, as an method, such as: Biodiversity Conservation
institution mandated by Indonesia Orangutan Technical Assistance in 2012, 2015, 2017;
Action Plan 2007-2017, conducted several
West Kalimantan BKSDA in 2012; Central
activities in Kalimantan prior to PHVA 2017,
Kalimantan BKSDA in 2013; Bukit Baka-
namely:
Bukit Raya National Park Management
1. Training for Standardizing Survey and Unit in 2012, 2013; and Betung Kerihun
Observation Method National Park Management Unit in 2013.
FORINA conducted several capacity Two guideline books were released
building trainings related on enhancing by FORINA and partners to support
capacity of Indonesia human resources standardize of survey method in 2012, i.e.:
on orangutan conservation program and Buku Panduan Survei Sarang Orangutan
biodiversity protection, such as training (written by S. S. Utami-Atmoko and M. A.
for standardizing survey and observation Rifqi) and Panduan Lapangan Pengenalan
method. FORINA recommended a Jenis Mamalia dan Burung Dilindungi
systematic design of line transects with di Sumatera dan Kalimantan (written
randomly sampling as standard method for by S. S. Utami-Atmoko, M. A. Rifqi and
orangutan survey. In total 95 participants Gondanisam).
were trained by FORINA on introduction
2. Kalimantan Wide Survey 2
of orangutan ecology, theory and
Kalimantan Wide Survey 2 (KWS 2) was
technique of nest survey for orangutan,
conducted during May-November 2012
tools practice, organizing field survey
in West Kalimantan, Central Kalimantan
and data analysis. The series of trainings and East Kalimantan and funded by
were supported by Ministry of Forestry The Nature Conservancy Indonesia.
and IFACS-USAID program, i.e.: West This survey was conducted by FORINA
Kalimantan on 16-17 September 2011, and collaborated with 12 conservation
East Kalimantan on 19-20 September organizations (FOKKAB, WWF Indonesia,
Riak Bumi, Titian Foundation, Palung
2011, and Central Kalimantan on 23-24
Foundation, PRCF Indonesia, Diantama
September 2011. Supported by FOKKAB-
Foundation, AKAR, FK3I, Indonesian
WWF Indonesia, FORINA conducted a Orangutan Foundation, Orangutan
similar training in West Kalimantan early Foundation-UK, Ecositrop), 2 universities
2011. FORINA personnel also were invited (University of Tanjungpura and University
as resource person and/or trainer on the of Mulawarman) and Ministry of Forestry
Ministry of Forestry’s unit capacity building units (BKSDA and Taman Nasional). The
survey started with 3 preparation training

Orangutan Population and Habitat Viability Assessment 97

 workshops was held to standardize the information. Meanwhile, the Web-GIS was
survey method in Samarinda on 6th of May consisting of: latest orangutan distribution
2012, Pontianak on 9th of June 2012 and and other supporting data, such as: forest
Pangkalan Bun on 16th June 2012. Team cover, concessions, peat areas and land
survey conducted ground check to 36 use maps.
locations identified as predicted orangutan
habitat based on Kalimantan Wide Survey 1 4. Pre-PHVA Workshop
result. All of locations were located outside FORINA facilitated regional Pre-PHVA
the conservation area. Team identified workshop to gather additional information
orangutan presence through nest or direct relate on latest Orangutan distribution and
encounter, current habitat condition as threats in West Kalimantan on 15-16 of
well as potential and existing threats. The June 2015, Central Kalimantan on 24-25
orangutan distribution map was updated of June 2015, North Sumatera and Aceh
base on the results of KWS 2 result that on 29-30 of September 2015 with in total
removed 6 locations in Central Kalimantan 176 people were participated. Meanwhile,
and 5 locations in West Kalimantan. the national Pre-PHVA workshop was
conducted in Bogor on 23-27 of May
3. Database Development Collect
2016 and participated by 85 people. In
FORINA started to collect related data in the workshops, the participants discussed
2013 as a preparation activity for 2013 relevant data or information in each
Orangutan Action Plan Evaluation. During population, source of information and
the regional meeting in North Sumatera method to verify the information. The Pre-
and Aceh on 19-21 of August 2013, West PHVA workshops resulted confirmation
Kalimantan on 5-6 of September 2013 and and completed maps on orangutan
Central Kalimantan on 2-3 of September distribution in Sumatera and Kalimantan
2013, FORINA were collected various as well as identified threats for Orangutan
tabular and spatial data from Ministry of sustainability in each population.
Forestry’s units, regional Orangutan Forum
(such as: FOKUS, FORA, FOKKAB, FORKAH
and KORAN), local governments and
conservation organizations, academia and
private sectors. In total 222 organizations
were participated in the evaluation process
events that funded by IFACS-USAID. Based
on these inputs, FORINA established
online database and spatial database on
website (Web-GIS) of orangutan (can be
access at webgis.forina.or.id). The online
database system was collected orangutan
in rehabilitation center information,
human-orangutan conflict data, and
survey information conducted by the
entire FORINA network, such as: transect
location, transect observations, nest decay,
and other related orangutan survey site

98 Orangutan Population and Habitat Viability Assessment

 Appendix II
PHVA collaborators
Steering Committee
NO POSITION NAME INSTITUTION
Director General of Ecosystems and
1 Patron Tachrir Fathoni, Ph.D. Nature Resources Conservation, Ministry
of Environment and Forestry
Director of Biodiversity Conservation,
2 Chief Bambang Dahono Adji
Ministry of Environment and Forestry
Biological Research Center, Indonesian
3 Hari Sutrisno, Ph.D.
Institute of Sciences
4 Prof. Jatna Supriatna, Ph.D. Indonesian Academy of Sciences
5 Jito Sugardjito, Ph.D. Universitas Nasional
Research, Development and Inno-
6 Prof. Ris. Dr. M. Bismark vation, Ministry of Environment and
Member Forestry
7 Noviar Andayani, Ph.D. University of Indonesia
Directorate of Biodiversity Conservation,
8 Puja Utama
Ministry of Environment and Forestry
9 Samedi, Ph.D. KEHATI Foundation
10 Sri Suci Utami Atmoko, Ph.D. FORINA-UNAS
11 Wahjudi Wardojo The Nature Conservancy

Organizing Committee
NO POSITION NAME INSTITUTION
Director General of Ecosystems and
1 Patron Tachrir Fathoni, Ph.D. Nature Resources Conservation, Ministry
of Environment and Forestry
Director of Biodiversity Conservation,
2 Bambang Dahono Adji
Ministry of Environment and Forestry
Supervisor
3 Puja Utama Ministry of Environment and Forestry
4 Herry Djoko Susilo FORINA
5 Chief I Aldrianto Priadjati, Ph.D. FORINA
6 Chief II Badiah Achmad Ministry of Environment and Forestry
7 Secretariat Coordinator Ermayanti. FORINA
8 Febriany Iskandar Ministry of Environment and Forestry
Secretariat Members
9 Drajat Dwi Hartono Ministry of Environment and Forestry
10 Frida Mindasari Saanin FORINA
Treasurers
11 Rini Aryani Ministry of Environment and Forestry
12 Plenary Coordinator Dr. Pahrian Siregar FORINA

Orangutan Population and Habitat Viability Assessment 99

 NO POSITION NAME INSTITUTION
13 Desi Satya Chandradewi Ministry of Environment and Forestry
14 Fitty Machmudah Ministry of Environment and Forestry
15 Indra Exploitasia Ministry of Environment and Forestry
16 Irham Fauzi FORINA
Plenary Member
17 Joko Nugroho Ministry of Environment and Forestry
18 Mohamad Arif Rifqi FORINA
19 Niken Wuri Handayani Ministry of Environment and Forestry
20 Rizal Buchari The Nature Conservancy
21 Logistic and Accommo- Herdiana Ministry of Environment and Forestry
22 dation Susi Oktalina Ministry of Environment and Forestry
23 Egi Ridwan Ministry of Environment and Forestry
Documentation
24 Fajar Saputra FORINA

PHVA Participants
NO NAME INSTITUTION
1 Dr. Ade Soeharso Orangutan Foundation-UK
2 Adiyar Bureau of Planning and Cooperation, Ministry of Energy and Mineral Resources
Directorate of Environmental Services Utilization of Conservation Forests, the
3 Agung M
Ministry of Environment and Forestry
4 Albertus Tjiu WWF Indonesia
5 Aldrianto Priadjati, Ph.D. FORINA
6 Prof. Dr. Ani Mardiastuti Faculty of Forestry, Bogor Agricultural Institute
7 Prof. Dr. Anne Russon Kutai National Park
8 Ari Meididit WWF Indonesia
9 Azhari Purbatrapsila Orangutan Foundation-UK
10 Badiah Achmad Ministry of Environment and Forestry
11 Bernat Ripoll Capilla Borneo Nature Foundation
12 Prof. Dr. Birute Mary Galdikas Orangutan Foundation International
13 Caroline Lees CBSG-IUCN
14 Chaerul Saleh Association of Indonesian Primate Experts and Observers (PERHAPPI)
15 Dedi Yansyah Aceh Forum (FORA)
16 Desi Satya Chandradewi Ministry of Environment and Forestry
17 Diaz Sari Pusparini Bogor Agricultural Institute
18 Donna Simon WWF Sabah
19 Drajat Dwi Hartono Ministry of Environment and Forestry
20 Egi Ridwan Ministry of Environment and Forestry
21 Eko Praptono Ministry of Agriculture
22 Eko Prasetyo Borneo Orangutan Survival Foundation
23 Ermayanti FORINA
24 Ettie Tatiana Conservation and Natural Resources Authority of Central Kalimantan
25 F. Maftukhakh Hilmya Nada Ministry of Environment and Forestry
26 Fajar Dewanto Orangutan Foundation International
27 Fajar Saputra FORINA
28 Fika Rahimah Borneo Orangutan Survival Foundation

100 Orangutan Population and Habitat Viability Assessment

NO NAME INSTITUTION
Director General of Conservation of Natural Resources and Ecosystems
29 Fitri Noor Chasanatun
(Sumatra)
30 Fitty Machmudah Ministry of Environment and Forestry
31 Frida Mindasari Saanin FORINA
32 Gail Campbell-Smith, Ph.D. International Animal Rescue
33 Hadi Sofyan Conservation and Natural Resources Authority of Aceh
34 Hardi Baktiantoro Centre for Orangutan Protection
35 Hari Sutrisno, Ph.D. Biological Research Center, Indonesian Institute of Sciences
36 Hendra Gunawan, Ph.D. Forestry Research and Development
37 Hendrik Segah, Ph.D. Central Kalimantan Forum (FORKAH)
38 Herry Djoko Susilo FORINA
39 Ian Singleton, Ph.D. PanEco Foundation - Sumatra Orangutan Conservation Programme
40 Iman Sapari Indonesian Orangutan Foundation (YAYORIN)
41 Irham Fauzi FORINA
Directorate of Essential Ecosystems Management, the Ministry of Environment
42 Irni Syafriani
and Forestry
43 Dr. Jamartin Sihite Borneo Orangutan Survival Foundation
44 Jito Sugardjito, Ph.D. Universitas Nasional
45 Julius Siregar Frankfurt Zoological Society
46 Karmele Llano Sanchez International Animal Rescue
47 Kathy Traylor-Holzer, Ph.D. CBSG-IUCN
48 Khairul Azmi North Sumatra Forum (FOKUS)
49 Kuswandono Gunung Leuser National Park
50 Larissa D. Salaki University of Indonesia
51 Prof. Ris. Dr. M. Bismark R&D and Innovation, Ministry of Environment and Forestry
52 Made Wedana FORINA
53 Maria Ulfah FORINA
54 Maria Voigt Max Planck Institute Evan / IDIV
55 Matthew G. Nowak PanEco- Sumatra Orangutan Conservation Programme
56 Melvin Gumal, Ph.D. WCS Malaysia
57 Mohamad Arif Rifqi FORINA
58 Muhammad Syamsuri West Kalimantan Forum (FOKKAB)
59 Niken Wuri Handayani Ministry of Environment and Forestry
60 Nurdita National Development Planning Agency (BAPPENAS)
61 Dr. Pahrian Siregar FORINA
62 Panut Hadisiswoyo North Sumatra Forum (FOKUS)
63 Prima Lady Universitas Nasional
64 Puja Utama Directorate of Biodiversity Conservation, Ministry of Environment and Forestry
65 Purwo Kuncoro Kutai Orangutan Project
66 R. Ramayadi Ministry of Agriculture
67 Renie Djojoasmoro Orangutan Foundation International
68 Rizal Buchari The Nature Conservancy
69 Robert Yappi Orangutan Foundation International
70 Sendi Yusandi Ministry of Environment and Forestry
71 Prof. Dr. Serge A. Wich Liverpool John Moores University
72 Sigit Ibrahim The Aspinall Foundation

Orangutan Population and Habitat Viability Assessment 101

 NO NAME INSTITUTION
73 Simon Husson, Ph.D. Borneo Orangutan Survival Foundation / Borneo Nature Foundation
74 Sofian Iskandar Forestry Research and Development
75 Sri Suci Utami Atmoko, Ph.D. FORINA-UNAS
76 Sylvia Ng WCS Malaysia
77 Dr. Tatang Mitra Setia Universitas Nasional
78 Tonny Soehartono, Ph.D. ADB – HOB
79 Truly Santika University of Queensland
Directorate of Essential Ecosystems Management, the Ministry of Environment
80 Vidya Sari Nalang
and Forestry
81 Wahjudi Wardojo The Nature Conservancy
82 Yarrow Robertson Orangutan Foundation-UK
83 Yaya Rayadin, Ph.D. East Kalimantan Forum (KORAN)
84 Yulita Kabangnga Kutai National Park Authority

102 Orangutan Population and Habitat Viability Assessment

 Appendix III
Data for Pongo abeli

The following data were collated by the medium scale agricultural encroachment
Pongo abelii working group during the
Mining: Normally legal if large scale but also
2016 PHVA workshop. Estimates for current
sometimes smaller scale and illegal.
population size and carrying capacity (K) were
derived from GIS models, except for the two
Energy projects. Predominantly legal hydro-
reintroduction sites, Bukit Tiga Puluh and
electric and geothermal.
Jantho. Habitat loss rates are derived from GIS
models for all sites. Settlement. Both legal settlement expansion
and establishment of illegal new settlements.
Definitions:
Agricultural encroachment (medium
Poaching as trade. Deliberate killing/removal
scale). Intended to include illegal medium
of orangutans to obtain infants (still live) for
sized plantations and encroachment of
pets
dozens up to hundreds or even thousands of
hectares.
Conflict killing. Killing of orangutans in
conflict situations, sometimes leading to
Agric. encroachment (small scale). Much
surviving infants becoming pets
smaller illegal encroachment of a few or a few
tens of hectares.
Hunting/food. Deliberate hunting and killing
of orangutans for food
Fires/burning forest. Intended to represent
fires outside of areas being converted for
Reintroduction. Introduction of new animals
agriculture and plantation conversion.
into the population

Palm oil plantations. Large scale plantations

usually with permits

Timber/pulp & paper plantations. Large

scale concessions usually with permits

Road construction. Legal & illegal, outside

concessions

Illegal logging. Random small scale illegal

logging. In some cases, followed by small and

Orangutan Population and Habitat Viability Assessment 103

 Table 22. Pongo abelii site designations (Population/area), estimated current orangutan population size (Pop. est.) and carrying capacity (Est. K), and
estimated rates of loss resulting from direct removal of orangutans or as a result of habitat loss.

104
REMOVAL or LOSS of orangutans from the
HABITAT LOSS
population
Population / area Pop. Est. K Pop. trend Cause Intensity Rate Cause Intensity Rate Impact
est. (H/M/L) (H/M/L)

West Leuser 5,922 5,922 Declining Poaching as L 7 adult females Total forest loss - 0.29% 100% reduction of K in
trade and 7 infants per converted area
year
Conflict killing L 21 per year? Palm oil plantations M 0.0276
Hunting/food L 0 Timber/pulp & paper planta- L 0.0138
tions
Road construction H 0.0414
Illegal logging M 0.0276
Mining M 0.0276
Energy projects H 0.0414
Settlement L 0.0138
Agricultural encroachment M 0.0276

Orangutan Population and Habitat Viability Assessment

(medium scale))
Agric. Encroachment (small M 0.0276
scale)
Fires/burning forest L 0.0414
Sikulaping (Pakpak 261 261 Declining Poaching as L 0.5 adult female Total forest loss - 0.01% 100% reduction of K in
Bharat) trade and 0.5 infants converted area
per year
Conflict killing L 1 per year Palm oil plantations L 0.0005
Hunting/food - - Timber/pulp & paper planta- L 0.0005
tions
Road construction L 0.0005
Illegal logging M 0.0010
Mining L 0.0005
Energy projects L 0.0005
Settlement L 0.0005
Agricultural encroachment L 0.0005
(medium scale))
Agric. Encroachment (small M 0.0010
scale)
Fires/burning forest L 0.0005
 REMOVAL or LOSS of orangutans from the
HABITAT LOSS
population
Population / area Pop. Est. K Pop. trend Cause Intensity Rate Cause Intensity Rate Impact
est. (H/M/L) (H/M/L)

East Leuser 5,779 5,779 Declining Poaching as L 9 adult females Total forest loss - 0.33% 100% reduction of K in
trade and 9 infants per converted area
year
Conflict killing L 18 per year Palm oil plantations H 0.0471
Hunting/food L 0 Timber/pulp & paper planta- L 0.0157
tions
Wounding (for - 4 per year Road construction H 0.0471
crop guarding
Illegal logging M 0.0314
and scare)
Mining M 0.0314
Energy projects H 0.0471
Settlement M 0.0314
Agricultural encroachment H 0.0471
(medium scale))
Agric. Encroachment (small M 0.0314
scale)
Fires/burning forest L 0.0471
Tripa Swamp 212 212 Declining Poaching as L 1 adult female Total forest loss - 11.48% 100% reduction of K in
trade and 1 infant per converted area
year
Conflict killing L 1 per year Palm oil plantations H 1.6400
Hunting/food L 0 Timber/pulp & paper planta- L 0.5467
tions
Fire (Medium) - 1 per year Road construction H 1.6400
Illegal logging H 1.6400
Mining L 0.5467
Energy projects L 0.5467
Settlement L 0.5467
Agricultural encroachment H 1.6400
(medium scale))

Orangutan Population and Habitat Viability Assessment

Agric. Encroachment (small H 1.6400
scale)
Fires/burning forest H 1.6400

105
 REMOVAL or LOSS of orangutans from the
HABITAT LOSS
population
Population / area Pop. Est. K Pop. trend Cause Intensity Rate Cause Intensity Rate Impact

106
est. (H/M/L) (H/M/L)

Trumon-Singkil 1,269 1,269 Declining Poaching as L 1.5 adult female Total forest loss - 0.43% 100% reduction of K in
trade and 1.5 infant per converted area
year
Conflict killing L 3 per year Palm oil plantations M 0.0410
Hunting/food L 0 Timber/pulp & paper planta- L 0.0614
tions
Wounding (for - 1 per year Road construction H 0.0614
crop guarding
and scare)
Fire (low) - - Illegal logging H 0.0614
Mining L 0.0205
Energy projects L 0.0205
Settlement M 0.0410
Agricultural encroachment H 0.0614
(medium scale))

Orangutan Population and Habitat Viability Assessment

Agric. Encroachment (small H 0.0614
scale)
Fires/burning forest H 0.0614
Siranggas/ Batu 87 87 Declining Poaching as L 0.5 adult female Total forest loss - 0.10% 100% reduction of K in
Ardan trade and 0.5 infant per converted area
year
Conflict killing L 1 per year Palm oil plantations L 0.0048
Hunting/food - - Timber/pulp & paper planta- L 0.0048
tions
Road construction L 0.0048
Illegal logging H 0.0143
Mining H 0.0143
Energy projects L 0.0143
Settlement M 0.0095
Agricultural encroachment M 0.0095
(medium scale))
Agric. Encroachment (small H 0.0143
scale)
Fires/burning forest L 0.0048
 REMOVAL or LOSS of orangutans from the
HABITAT LOSS
population
Population / area Pop. Est. K Pop. trend Cause Intensity Rate Cause Intensity Rate Impact
est. (H/M/L) (H/M/L)

West Batang Toru 604 604 Declining Poaching as L 0.5 adult female Total forest loss - 0.03% 100% reduction of K in
trade and 0.5 infant per converted area
year
Conflict killing L 1.99 adult male Palm oil plantations M 0.0029
per year
Hunting/food L 0.89 per year Timber/pulp & paper planta- L 0.0043
tions
Road construction H 0.0043
Illegal logging M 0.0029
Mining M 0.0029
Energy projects H 0.0043
Settlement M 0.0029
Agricultural encroachment M 0.0029
(medium scale))
Agric. Encroachment (small H 0.0043
scale)
Fires/burning forest L 0.0014
East Batang Toru 162 162 Declining Poaching as L 0.5 adult female Total forest loss - 0.03% 100% reduction of K in
(Sarulla) trade and 0.5 infant per per year converted area
year
Conflict killing L 0.99 adult male Palm oil plantations M 0.0029
per year
Hunting/food - 0.45 per year Timber/pulp & paper planta- L 0.0014
tions
Road construction H 0.0043
Illegal logging M 0.0029
Mining M 0.0029
Energy projects H 0.0043
Settlement M 0.0029
Agricultural encroachment M 0.0029
(medium scale)

Orangutan Population and Habitat Viability Assessment

Agric. Encroachment (small H 0.0043
scale)

107
Fires/burning forest L 0.0014
 REMOVAL or LOSS of orangutans from the
HABITAT LOSS
population

108
Population / area Pop. Est. K Pop. trend Cause Intensity Rate Cause Intensity Rate Impact
est. (H/M/L) (H/M/L)

Bukit Tiga Puluh Landscape Total forest loss - 1.89% 100% reduction of K in
converted area
No. in original 137 1,560 Increasing Re-introduction - +8 per year Palm oil plantations - -
table
No. released 171 Conflict killing - Timber/pulp & paper planta- - -
tions
No. released x 70% 120 Hunting/food - Road construction - -
survival
Illegal logging - -
Mining - -
Energy projects - -
Settlement - -
Agricultural encroachment - -
(medium scale))

Orangutan Population and Habitat Viability Assessment

Agric. Encroachment (small - -
scale)
Fires/burning forest - -
Jantho landscape Total forest loss - 0.001% 100% reduction of K in
converted area
No. in original 62 400 Increasing Re-introduction - +20 per year Palm oil plantations L 0.00005
table
No. released 99 Conflict killing - 0 Timber/pulp & paper planta- L 0.00005
tions
No. released x 70% 69 Hunting/food - 0 Road construction M 0.00010
survival
Illegal logging M 0.00010
Mining L 0.00005
Energy projects L 0.00005
Settlement L 0.00005
Agricultural encroachment L 0.00005
(medium scale))
Agric. Encroachment (small L 0.00005
scale)
Fires/burning forest H 0.00014
 This appendix provides details of the information collated or estimated by the P. p. morio working group.

Table 23. Pongo pygmaeus morio: designated populations and their characteristics

Habitat
Meta- Within MP Number of Total Habitat Estimated number of Estimation method (survey/ Estimated
No Management
population units fragments Area km2 orangutans density from elsewhere/guess) Carrying capacity
Unit
349 OU released in 1997-2002 # released/ nest census YR
Beratus
1 1 Camp Beratus 1 200,000 ha Estimated 30-40 OU in the 400 Survey by Rayadin and team NA
Landscape
km2 survey area (2007)
4,000 ha
(Protection
Minimum 20 OU
Forest and 1998 nest census and birth
Sungai Wain (97 OU released in 1992-
2 1 - 1 connected record NA
Landscape 1997, but some OU moved to
forest/
Meratus)
agroforestry
surrounding)
65,000 ha 8 nests found in 10 km2 and
CA Muara Minimum 2 OU
1 only 10 km2 3 km transect by Rayadin and 5 OU (10 km2)
Kaman (base on nest characteristic)
suitable) team (2016)
1,500 OU (BTNK)
Nest Survey by Kutai National
192,000 ha Minimum 2,097 OU (Rayadin) Park Authority (BTNK) (2015)
Kutai NP 1 (only 130,000 Nest survey by Rayadin & team 1,511 OU
ha suitable) 2010, TNK Main Zone and
Bufferzone

Kutai NP- Camera traps and survey by

Bontang PF 1 15,000 ha Minimum 11 OU 11 OU
3 Bonrang 1 Rayadin & Team (2013)
Landscape 200,000 ha
Timber Estate (140,000 ha Nest survey and camera trap
-SRH 9 in SRH and 80 to 120 OU by Rayadin Y, Spehar S and -
-SHJ 60,000 ha in Team (2012-2016)
SHJ)
Coal Mining

Orangutan Population and Habitat Viability Assessment

concessionaire
Total Nest survey and camera trap
(KPC: 3 sites, Minimum 29 OU
12 concessionaire by Rayadin Y, and Team (2012- 11 OU
Indominco:
Data for Pongo p. morio
Appendix IV

250,000 ha 2016)
5 sites JMB

109
Group: 3 sites)
 Habitat

110
Meta- Within MP Number of Total Habitat Estimated number of Estimation method (survey/ Estimated
No Management
population units fragments Area km2 orangutans density from elsewhere/guess) Carrying capacity
Unit
Hutan Kota PKT 1 300 ha 3 OU Direct sighting by BTNK (2014) 3 OU
Palm Oil
concessionaire Nest survey and camera trap
15 50,000 ha 30 to 80 OU by Rayadin and Team (2012- NA
2016)

4,975 ha (HCV Line transect method by UNAS

PT REA Kaltim 8 29 OU NA
Forest) team (2011)
Belayan-Senyiur Line transect method by UNAS
4 PT KMS 5 1,879 ha 35 OU NA
Landscape team (2014)
Senyiur Natural Nest survey and camera trap
1 200,000 ha > 160 OU 160 OU
Forest by Rayadin and Team (2015)
86,450 ha
38 OU (40 OU released with 3
Kehje Sewen 1 (suitable only Data from BOSF 150 OU

Orangutan Population and Habitat Viability Assessment

OU dead and 1 OU born)
22,000 ha)
397 individual with density
Wehea
1.05 (0.16-6.01) indv./Km21but Survey by TNC (2012), Sphear
Protection 1 38,000 ha is difficult to obtain. The endangered orangutan 397 OU
et al (2015)
Forest (Pongo spp.

Wehea-Lesan Landscape
5 1
Landscape Sourounding
Wehea (PT 263,830
Narkata Rimba, ha (include 409 to 424 OU Nest Survey by TNC (2002
Gunung Gajah 6 customary to 2015) and Line transect 350 OU
Abadi, Karya forest, PT. NAS method by BOSF (2016)
Lestari, DSN, and PT. GPM)
AAU, NAS and
GPM
- > 70 OU

- 189 individual with density

1.65 (1.50-1.82) indiv/Km2
Nest survey and camera trap
(2008)
Lesan by Rayadin and Team (2013)
11,344 ha
1 Protection 1 Nest Count Line Transect by 189 OU
- 93 individual with
Forest density 0.81 (0.62-1.04) Mathewson et al (2008) and
indiv/Km2 (2015)2 Alkema (2015)
 Habitat
Meta- Within MP Number of Total Habitat Estimated number of Estimation method (survey/ Estimated
No Management
population units fragments Area km2 orangutans density from elsewhere/guess) Carrying capacity
Unit
Karst
Pangadan Nest survey and camera trap
Bayanak 3 > 60,000 ha 30 to 40 OU by Rayadin and Team (2012- NA
Sei Bulan 2016)
Karangan
PT Anugerah Line transect method by BOSF
NA 40,000 ha 10 to 15 OU -
Energitama (2016)
Timber 60,000 ha Nest survey and camera trap
Sangkulirang Plantation 2 (90% natural > 240 OU by Rayadin and Team (2012- -
6 1 Concessionaire forest) 2016))
Landscape
Direct sighting report by COP
8 OU (COP) 8 OU
Sawit
Gunta Samba, 4 40,000 ha Nest survey and camera trap
Telen by Rayadin and Team (2012-
> 40 OU (YR) 40 OU
2016)
Marai and Baai
2 - 1.42 indv/Km2 Marshall et al (2007) -
Karst Forest
Gunung Nyapa 1 - 0.82 indv/km2 Marshall et al (2007) -
Nest census by Alfred et al.
Tabin FR 1 120,000 1,197 OU (868 to 1,606 OU) 2,000 OU
Tabin Range (2010)
7 1
Landscape Nest census by Ancrenaz et al. 150 OU
Silabukan 1 10,000 ha 58 OU (21 to 159 OU)
(2005)
Nest census by Alfred et al.
Danum Valley - 48,000 ha 425 OU (309 to 570 OU) 900 OU
(2010)
Nest census by Ancrenaz et al.
2,600-3,000 OU (1,295 to
USM 1 161,100 ha (2005, 2010); and Alfred et al. 4,000 OU
Central 5,866 OU)
(2010)
8 Forest Range 1
Landscape Sabah
Foundation Nest census by Ancrenaz et al.,
2,000 OU
Forest 1 429,400 ha 2,100 OU (2005, 2010); and Alfred et al.
Concession (2010)
Area
Lower
Lower Nest census by Ancrenaz et al.,
Kinabatangan 1 51,720 ha 700-825 OU (546 to 955 OU) 900 OU
Kinabatangan (2005), and Alfred et al. (2010)
9 1 Floodplain
Range

Orangutan Population and Habitat Viability Assessment

Landscape Nest census by Ancrenaz et al., 600 OU
Kulamba FR 1 21,000 ha 480 OU (276 to 1,214 OU)
(2005), Alfred et al. (2010)
North
Deramkot FR,

111
Kinabatangan
Tangkulap FR, 1,700-2,100 OU (1,016 to Nest census by Ancrenaz et al., 3,000 OU
10 Range 1 1 ca 140,000 ha
Segaliud Lokan 3,043 OU) (2005), Alfred et al. (2010)
Landscape
FR
112
Habitat
Meta- Within MP Number of Total Habitat Estimated number of Estimation method (survey/ Estimated
No Management
population units fragments Area km2 orangutans density from elsewhere/guess) Carrying capacity
Unit
Ulu
Ulu Kalumpang Kalumpang,
144 OU (54 to 408 OU) to 605 Nest census by Ancrenaz et al., 800 OU
11 Range 1 Tawau Hills 1 70,000 ha
(487 to 783 OU) (2005), Alfred et al. (2010)
Landscape Park, Mt
Wullersdorf
Crocker Range
Nest census by Ancrenaz et al.
12 Landscape 1 - 1 90,000 ha 181 OU (62 to 528 OU) 300 OU
(2005)

150 OU
Lingkabau FR 1 30,000 ha 100 OU (75 to 150 OU) Nest census by Payne (1987)
Lingkabau
13 1
Landscape Nest census by Ancrenaz et al. 150 OU
Kinabalu Park 1 20,000 ha 50 OU (25 to 75 OU)
(2005)
Nest census by Ancrenaz et al.

Orangutan Population and Habitat Viability Assessment

Bonggaya Bonggaya FR 1 60,000 ha 111 OU (38 to 324 OU) 150 OU
14 1 (2005)
Landscape
Trusan Sugut FR 1 3,844 ha 79 OU (38 to 121 OU) WWF Report (2014) 150 OU
Ulu Tungud Nest census by Ancrenaz et al.,
15 1 Ulu Tungud FR 1 72,000 ha 29 OU (9 to 99 OU) 80 OU
Landscape (2005)
Trus madi
Nest census by Ancrenaz et al.,
16 Landscape 1 Trus Madi FR 1 68,000 ha 282 OU (126 to 736 OU) 350 OU
(2005)

Sepilok
17 1 Sepilok FR 1 4,000 ha 200 OU (100 to 300 OU) Nest census by Payne (1987) 300 OU
Landscape
 Table 24. Pongo pygmaeus morio: threats and their estimated impacts on designated populations (K=carrying capacity).

REMOVAL or LOSS of orangutans from

HABITAT LOSS
the population
Meta Population / area Current Est. K Pop. Cause Intensity Rate Cause Intensity Rate Impact
population population trend (H/M/L) (H/M/L)
estimate
Beratus Beratus Protection 349 OU NA Declining Human- Medium No info Illegal logging High BOSF survey, 2005 Wide ranging
Landscape Forest released in orangutan local settling - illegal loggers cleared disturbance of
1997-2002 conflict Forest fire Medium about 3.975-4.24 Ha orangutans
Estimated per day
30-40 OU in
the 400 km2 Yaya Rayadin:
survey area PT ITCI logging
concession in Beratus
landscape: 200,000
Ha
Sungai Wain Sungai Wain Minimum 20 NA Declining - - - Encroachment Medium No info Reduction of K
Landscape Protection Forest OU 5 OU Declining - - - Road High 2% per year 100% reduction
CA Muara Kaman (97 OU construction High High of K for
released in Forest fire orangutans
1992-1997,
but some OU
moved to
Meratus) Illegal logging
Minimum 2 Road
OU Construction
(base on nest Forest fire
characteristic)

Orangutan Population and Habitat Viability Assessment

113
 REMOVAL or LOSS of orangutans from
HABITAT LOSS
the population

114
Meta Population / area Current Est. K Pop. Cause Intensity Rate Cause Intensity Rate Impact
population population trend (H/M/L) (H/M/L)
estimate
Kutai NP- Kutai NP 1,500 OU 1,511 Variable Killing Low to 1 mati Habitat High Conversion area in In total 3.9%
Bontang (BTNK) OU Conflict Medium 2016 Conversion - 2015: 78.16 km2 habitat
Landscape Minimum mining reduction from
2,097 OU Illegal logging Encroachment area 1995 condition
(Rayadin) Forest fire in 2011-2016: 24.69
Encroachment km2
Bontang PF Minimum 11 11 OU Declining Conflict High ?? Habitat High Rate 2 km2/year 80% reduction
OU Conversion of K for
- 60% Coal orangutans
mining, other
land use &
settlement
Encroachment
Road
Construction
Settlement

Orangutan Population and Habitat Viability Assessment

Increase
of human
population
Timber Estate: SRH 80 to 120 OU NA Declining Conflict High 20 OU Land clearing High High 40% reduction
& SHJ relocated (timber estate) of K in
(2012- conservation
2015) area
Coal Mining: KPC, Min. 29 OU 11 OU Variable - - - Land clearing High 5 km2/ year since 60% reduction
Indomincodan (mining) 1980’s of K in all of
JMB Group concession
Hutan Kota PKT 3 OU 3 OU Declining Conflict Low 3 OU killed - - - -
by forest
fire in 2016
in local
community
land
Sawit 30 to 80 OU NA Declining Conflict - - Conversion to High High -
palm oil
Encroachment
in conservation
area inside the
concessionaire
 REMOVAL or LOSS of orangutans from
HABITAT LOSS
the population
Meta Population / area Current Est. K Pop. Cause Intensity Rate Cause Intensity Rate Impact
population population trend (H/M/L) (H/M/L)
estimate
Belayan-Senyiur PT REA Kaltim 29 OU NA Declining - - - Road - - -
Landscape construction
(public)
PT KMS 35 OU NA Stable - - - Illegal logging - - -
(iron wood)
Senyiur Natural > 160 OU 160 OU Declining Conflict Medium No info Forest fire Medium 10 km2/ year 60% decline
Forest Habitat in K
conversion (oil
palm, timber
estate, mining)
Wehea –Lesan Kehje Sewen 38 OU 150 OU Increase Illness Low 1 OU in 2 - - - -
Landscape (40 OU years
released with
3 OU dead
and 1 OU
born)
Gunung Gajah 99 OU 150 OU Declining Conflict Low No info Legal logging Medium 10 km2 AAC Decline in K
concession
PT Narkata Rimba, 409 to 424 350 OU Declining Conflict Low No info Land clearing Medium 10 km2 Annual
GG Abadi, Karya OU for palm oil Allowable Cut (AAC)
Lestari, Hutan and timber
Adat Wehea, DSN plantation
(oil palm), AAU
(Timber estate),
NAS (oil Palm) dan
GPM
Lesan Protection > 70 OU 70 OU Declining - - - Forest fire Medium 2 km2/ year 40% decline
Forest Illegal logging in K
Encroachment

Orangutan Population and Habitat Viability Assessment

115
 REMOVAL or LOSS of orangutans from
HABITAT LOSS
the population
Meta Population / area Current Est. K Pop. Cause Intensity Rate Cause Intensity Rate Impact

116
population population trend (H/M/L) (H/M/L)
estimate
Sangkulirang Karst 30 to 40 OU NA Stable No - - - - - Stable
Landscape Pangadan
Bayanak
Sei Bulan
Karangan
PT Anugerah 10 to 15 OU NA - - - - - - - -
Energitama (Palma
Serasih Group)
Timber estate > 240 OU NA Declining Conflict Low No info Land clearing Medium 3,0 km2/ year 70% decline
(timber estate) in K
PT. Gunta Samba 8 OU (COP) NA Declining Conflict High 20 OU was Land clearing High No info 90% decline
(oil palm), telen > 40 OU (YR) relocated (oil palm) in K
in 2011-
2015
Tabin Range Tabin FR 1,197 OU 2,000 Stable - - 0 Fires (20 yrs - - No recent

Orangutan Population and Habitat Viability Assessment

Landscape (868 to 1,606 OU ago, no recent impact
OU) fires)
Silabukan 58 OU 150 OU Stable - - 0 Fires (20 yrs - - No recent
(21 to 159 ago, no recent impact
OU) fires)
Central Danum Valley 425 OU 900 OU Stable - - 0 - - - No recent
Forest Range (309 to 570 impact
Landscape OU)
USM 2,600-3,000 4,000 Stable - - - Fires (20 yrs - - No recent
OU (1,295 to OU ago, no recent impact
5,866 OU) fires)
Sabah Foundation 2,100 OU 2,000 Declining - - - Conversion High - 40% decline
Forest Concession OU to mosaic in K
Area plantation
Lower Lower 700-825 OU 900 OU Declining - - - fragmentation High - 10% decline
Kinabatangan Kinabatangan (546 to 955 in K
Range Floodplain OU)
Landscape
Kulamba FR 480 OU 600 OU Stable - - - - - - -
(276 to 1,214
OU)
North Deramkot FR, 1,700-2,100 3,000 Stable - - - Sustainable Medium - NA
Kinabatangan Tangkulap FR, OU (1,016 to OU logging
Range Segaliud Lokan FR 3,043 OU)
Landscape
 REMOVAL or LOSS of orangutans from
HABITAT LOSS
the population
Meta Population / area Current Est. K Pop. Cause Intensity Rate Cause Intensity Rate Impact
population population trend (H/M/L) (H/M/L)
estimate
Ulu Kalumpang Ulu Kalumpang, 144 OU 800 OU Declining - - - Geothermal High - 10% decline
Range Tawau Hills Park, (54 to 408 in K
Landscape Mt Wullersdorf OU) to 605
(487 to 783
OU)
Crocker Range Crocker Range 181 OU 300 OU Stable - - - - - - None
Landscape (62 to 528
OU)
Lingkabau Lingkabau FR 100 OU 150 OU Stable - - - - - - None
Landscape (75 to 150
OU)
Kinabalu Park 50 OU 150 OU Stable - - - - - - None
(25 to 75 OU)
Bonggaya Bonggaya FR 111 OU 150 OU Stable - - - - - - None
Landscape (38 to 324
OU)
Trusan Sugut FR 79 OU 150 OU Stable - - - - - - None
(38 to 121
OU)
Ulu Tungud Ulu Tungud FR 29 OU 80 OU Declining - - - Conversion High - 10% decrease
Landscape (9 to 99 OU) for mosaic in K
plantation
Trus madi Trus Madi FR 282 OU 350 OU Declining - - - Encroachment High - 10% decrease
Landscape (126 to 736 in K
OU)
Sepilok Sepilok FR 200 OU 300 OU Stable - - - - - - None
Landscape (100 to 300
OU)

Orangutan Population and Habitat Viability Assessment

117
 Table 25. Pongo pygmaeus pygmaeus: designated populations and their characteristics. Bold indicates the best population estimate for PVA models

Estimation method Estimated

Meta- Within MP Number of Total Habitat Estimated number of orangutans Sources and

118
No Habitat Management Unit (survey/density from Carrying
population units fragments Area (ha) (OU) and density Years
elsewhere/ guess) capacity (K)
BKNP (Embaloh and Sibau Watersh-
eed)
- 1.030 (550-1.830) individual
OU with density 0.00-1.44
OU/km2 (2006)

- 749 OU with density 0.56–0.67

OU/km2 (2009) 4,029 OU
Note:
Betung Kerihun National National Park
Park/BKNP and Protection Upstream of Labian-Leboyan Corridor at K Report WWF
Forest Surrounding National - 585 OU with density 0.69–5.84 Corridor Indonesia
1A Park (Embaloh Watershed 3 2 485,100 OU/km2 include lower corridor Line transect survey 60-70% of K (2006, 2009)
and Sibau Watershed, (2011) (1,120 OU) Report FORI-
Upstream of Labian-Leboyan Protection NA (2016)
Corridor) - 419 OU with density 0.948 Forest 50%
OU/km2 (2016) of K (676
1 OU)

Orangutan Population and Habitat Viability Assessment

Protected Forest
- 338 OU (based on estimation
population with in protected
forest based of PHVA orangutan
2016 modeling result)

Line-transect surveys
Batang Ai-Lanjak-Entimau for nest for Batang Ai
Landscape (Lanjak - entimau and Lanjak-Entimau
WS, Ulu Sungai Menyang, Marked Sign Count for 2,010 OU Report
Batang Ai NP, Engkari-Telaus, 1808 OU (average prediction from fresh nest for Batang Note: (1992)
1B 1 7 26,084
Lanjak-Entimau WS exten- estimates of different location) Ai and Lanjak-Entimau Has reached Report WCS
sion areas, Batang Ai NP (Distance) 90% of K (2007, 2016)
Extension areas, Ulu Pasin Marked Sign Counts
proposed extension) for fresh next using
Bayes analysis
679 individual OU, consist of
434 OU with in DSNP and 245 OU
in Downstream of Labian-Leboyan Report WWF
Danau Sentarum National Corridor (2016) Indonesia
2 Park/DSNP and Downstream 1 2 2 182,160 Estimation population based on Line transect survey at K (2009)
of Labian-Leboyan Corridor Survey in 2009: 771– 1,006 OU with Report FORI-
density 0.38–4.08 OU/km2 NA (2016)
Survey in lower corridor 2014-2016:
Appendix V. Data for P. p. pygmaeus

Density 0.278-0.421 OU/km2

 Estimation method Estimated
Meta- Within MP Number of Total Habitat Estimated number of orangutans Sources and
No Habitat Management Unit (survey/density from Carrying
population units fragments Area (ha) (OU) and density Years
elsewhere/ guess) capacity (K)
80 OU
Information
Klingkang Range National Prediction using minimum density
3 1 2 2 72,975 - at K from local
Park and Sintang Utara number of GIS modelling result (0.11
people
OU/km2)
94 OU Based on
Bungoh National Park-
Prediction using minimum density nest sighting
4 Gunung Nyiut NR and 1 2 1 86,096 - at K
number of GIS modelling result (0.11 2014 in
Penrisen HL
OU/km2) Bungo NP
HL Senujuh
29 OU
(2014) based
5 Pygmaeus fragmented North 1 1 4 20,948 Prediction using density number of Confirmed presence at K
from confis-
GIS modelling result (0.14 OU/km2)
cated
15 OU
WWF Report
6 Pygmaeus fragmented South 1 1 3 5,000 Prediction using density number of Line transect survey at K
2012
GIS modelling result (0.3 OU/km2)
Report WCS
(2007)
30 OU
Report SFC
Ulu Sebuyau-Sedilu Land- Prediction using minimum density
7 1 1 6 27,500 Confirmed presence at K (2015)
scape number of GIS modelling result (0.11
Report WCS
OU/km2)
(in prep.
2016)

Orangutan Population and Habitat Viability Assessment

119
 Table 26. Pongo pygmaeus pygmaeus: threats and their estimated impacts on designated populations.

REMOVAL or LOSS of orangutans from

HABITAT LOSS

120
the population
Current Est.
Population / Population Intensity Intensity
population carrying Cause Rate Cause Rate Impact
area trend (H/M/L) (H/M/L)
estimate capacity
1 adult per NP: no significance NP: lost 0% for 10
NP & Corridor: Poaching/ year Corridor: years
NP: low HL: Reduction
Betung Most stable Hunting (Since 2-3 encroachment: small Corridor: 0.5% per
2,990 4,029 Low Corridor: 20% of K in total
Kerihun Hutan Lindung: years ago no scale agriculture year for 10 years
low area
decline single case Hutan Lindung: illegal HL: 2% per year
documented) logging, settlement for 10 years
1 animal
Estimated at <1% <1% reduction in
Hunting recorded in Illegal logging
Batang Medium per year for 10 K for orangutans
for food Low past 5 years
Ai-Lanjak- years in total area
1,808 2,010 Stable HOC (Human 1 animal
Entimau Estimated at <1% <1% reduction in
orangutan Low recorded in Conversion for
Landscape Medium per year for 10 K for orangutans
conflict) the past 5 industrial agriculture
years in total area
years
NP: 5%
Danau
Encroachment: small reduction in K
Sentarum
scale agriculture NP: NP: 1 % for 10 for orangutans in
and Corridor Poaching/ 1-2 adult and

Orangutan Population and Habitat Viability Assessment

Conversion for Medium years total area
Labian 679 890 Declining Hunting 1 infant per
industrial agriculture Koridor: Surrounding NP: Corridor: 10%
Laboyan year
Road Construction High 10% for 10 years reduction in K
Downstream
for orangutans in
(Bawah)
total area
Klingkang
Range N/A (Malaysia)
1 adult for 2 1% per year for 10
National Park 80 80 N/A N/A Low Conversion for mining Medium Uncertain
years years
and Sintang Road construction
Utara
Bungoh N/A (Malaysia)
N/A
National Park- Encroachment: small
(Malaysia) 1 adult for 2 1% per year for 10
Gunung Nyiut 94 94 Declining Low scale agriculture N/A Uncertain
Poaching year years
NR + Penrisen Road construction
(Indonesia)
HL (Indonesia)
Conversion for Loss 10% of
Pygmaeus
2 – 3 adults industrial agriculture existing area for
fragmented 29 29 Declining Poaching High High Non Viable Area
per year -Fire 10 yrs (total loss:
North
-Fragmentation 100%)
Conversion for Loss 10% of
Pygmaeus
2 – 3 adults industrial agriculture existing area for
fragmented 15 15 Declining Poaching High High Non Viable Area
per year -Fire 10 yrs (total loss:
South
-Fragmentation 100%)
Ulu Sebuyau- Stopped
Poaching/ 1 adult per Conversion for Zero for the
Sedilu 30 30 - Medium for the Uncertain
Hunting year industrial agriculture moment
Landscape moment
 Table 27. Pongo pygmaeus wurmbii: designated populations and their characteristics

Habitat Lower Upper Lower Upper

Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

Pongo pygmaeus
wurmbii
West Kalimantan
4049 6681
Coastal Lowlands
Kubu Raya
798 1684
284,482

Kubu Raya Coastal unsurveyed 0.9 1.9 25% 159 336

70,743
(1) >150 in 20,000 ha in and
around PT. ATP (oil palm) (1.54 ind/
Sanggau 0.9 1.9 50% 138 291
km2, YIARI/BNF 2015) 30,664
(2) northern block unsurveyed

Mendawak unsurveyed, presence confirmed 0.9 1.9 50% 420 886

93,313

Fragmented landscape 0.9 1.9 10% 81 171

89,762

Gunung Palung-Sg Putri

2620 3945
198,769

(1) 2500 in GPNP, 90,000 ha

(Johnson et al., 2004); 1302-1939
in GPNP (YIARI, 2016)
(2) 326-482 in HL Gunung Tarak,
24,000 ha (2.01 ind/km2, YIARI/ 109.424
BNF 2013) (including
Gunung Palung NP-
(3) 49 in PT. Kayung Agro Lestari TNGP 79,000 100% 1727 2576
Gunung Tarak HL
(PT. KAL, oil palm) North region, & HLGT
820 ha (6.99 ind/km2, YIARI/BNF 24,000)
2015)
(4) 108 in Kuala Satong (PT KAL)
East region (4.35 ind/km2, FFI
2010)
(1) 900-1250 in Sg.Putri-Sg.Tolak,
55,000 ha (1.52-2.27 ind/km2,
Sungai Putri-Sungai YIARI/BNF 2012)
1.52 2.27 100% 836 1248

Orangutan Population and Habitat Viability Assessment

Tolak (2) 189 in PT. KAL south region, 54,997
5,000 ha (4.50 ind/km2, YIARI/BNF
2015)
Appendix VI Data for P. p. wurmbii

121
122
Habitat Lower Upper Lower Upper
Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

30-50 in PT Sinar Karya Mandiri

Sg. Pawan Hilir (North) (PT. SKM, oil palm) (best guess 0.9 1.9 75% 30 64
4,509
from patrol sightings)

Fragmented landscape 0.9 1.9 10% 27 57

29,839
Pematang Gadung
499 775
35,000
(1) 30-50 estimated in PT. Artu (oil
palm) - unsurveyed
Sg. Pawan Hilir (South) 0.9 1.9 75% 21 44
(2) 30 in PT. Limpah Sejahtera (PT. 3,111
LS, oil palm), company data
548-808 in 21,000 ha (two blocks)
Pematang Gadung (survey estimate 2.61-3.85 ind/ 2.61 3.85 100% 436 644
16,720
km2, YIARI/BNF 2012)

Orangutan Population and Habitat Viability Assessment

Pesaguan unsurveyed 0.9 1.9 50% 22 47
4,997

Batu Menangis unsurveyed 0.9 1.9 25% 17 35

7,365

Fragmented landscape 0.9 1.9 10% 3 5

2,807
Sungai Tengar
101 211
28,649
0.46 ind/km2 (brief survey YIARI/
Sungai Tengar 0.9 1.9 50% 33 69
BNF 2014) 7,274

Sungai Tapah unsurveyed 0.9 1.9 50% 50 105

11,023

Gunung Raya unsurveyed 0.9 1.9 25% 14 29

6,161

Fragmented landscape 0.9 1.9 10% 4 8

4,191
Kendawangan-Jelai
31 66
34,460
Kendawangan
heavily fragmented, unsurveyed 0.9 1.9 10% 4 8
landscape 4,181
Sungai Mading
heavily fragmented, unsurveyed 0.9 1.9 10% 15 32
landscape 16,679
 Habitat Lower Upper Lower Upper
Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

heavily fragmented, surveys by FFI,

Air Hitam landscape 0.9 1.9 10% 6 12
Andi Erman, 2006 (RESULTS??) 6,423

Fragmented landscape 0.9 1.9 10% 6 14

7,177
Southwest
Central 4745 6424
Kalimantan
Lamandau-Sukamara
516 752
68,049

Sukamara unsurveyed 0.9 1.9 25% 6 12

2,479
(i) 144 (BKSDA, monitoring 2015)
(ii) 960 (FORINA survey 2010) 56,962
(iii) 431-618 within reserve at mean (including SM
SM Lamandau 0.97 1.45 100% 502 724
D 0.97-1.45 ind/km2 including Lamandau
ca. 160 reintroduced individuals 49,600)
(OFUK/BNF survey 2016)

Fragmented landscape 0.9 1.9 10% 8 16

8,608
Kotawaringin Lama
437 850
69,703
(1) Large forest block, unsurveyed
Kotawaringin Lama (2) 10-30 in PT. Kalimantan Sawit
0.9 1.9 75% 229 483
Block Barat Abadi (PT. KSA, oil palm), 3,000 ha 33,863
(1.1-1.4 ind/km2, BOSF 2015)

Kotawaringin Lama
unknown 0.9 1.9 50% 34 73
Block Timur 7,637

71-77 in PT Korintiga Hutani

Kotawaringin Lama (PT. KTH, pulpwood), 10,040 ha
0.9 4.5 100% 71 77
Utara fragmented (0.88-4.5 ind/km2, 912
BOSF 2014)
150 in 5,000 ha, fragmented
Rawa Kuno landscape (KPHP/OFI). Includes Tanjung 0.9 1.9 75% 90 190
13,308

Orangutan Population and Habitat Viability Assessment

Keluang region

Fragmented landscape 0.9 1.9 10% 13 27

13,983

123
Tanjung Puting
3713 4655
205,694
 Habitat Lower Upper Lower Upper
Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

124
(1) Tanjung Puting NP : 6000
pre-fire in 415,040 ha (park area,
not forest area) (current BTNTP
estimate); density estimates 1.96 -
2.90 ind/km2, mean 2.45 ind/km2,
OFI survey 2004
188,680
(2) PT. Andalas Sukses Makmur
Tanjung Puting NP - (including
(PT. ASMR, oil palm), 1,000 ha 1.96 2.45 100% 3698 4623
Rimba Raya ERC 159,364 TNTP
on Sekonyer river before park
& 22,909 RR)
boundary; estimate 10 orangutans
(BOSF Survey 2013; density 0.8-
1.47)
(3) Rimba Raya; no wild orangutan
data; 100 ex-captive (OFI / RRC),
65,000 ha (~25,000 forested)

Fragmented landscape 0.9 1.9 10% 15 32

17,014
Seruyan-Sampit
79 167
87,714
(1) Makin Group (oil palm) : 44

Orangutan Population and Habitat Viability Assessment

individuals
(2) Tehang Group (oil palm) :
density estimate of 0.002 ind/km2
in 130 ha = <1 OU (BKSDA)
(3) PT. KIU (oil palm) : density
estimate of 1.0 ind/km2 in 145 ha
Fragmented landscape 0.9 1.9 10% 79 167
= 1 OU (BKSDA) 87,714
(4) PT. SSIK (oil palm): density
estimate of 0.3 ind/km2 in 40 ha =
<1 OU (BKSDA)
(5) Keruing : density estimate of
0.1 ind/km2 in 10 ha = <1OU
(BKSDA)
Katingan-Barito
14210 19428
lowlands
Katingan
3334 4709
254,915
3,012-4,139 in 192,300 ha (size
of ERC) pre-fire (mean 2.3 +/-0.6 201,759
Katingan ind/km2 mixed swamp forest; 0.76 (including 100% 3160 4343
ind/km2 low pole forest RMU / BNF 192,300 ERC)
surveys 2010/2013)
no recent surveys, presence
Kelaru confirmed at normal psf densities 0.9 1.9 75% 110 232
16,311
in 2003 (BNF)
 Habitat Lower Upper Lower Upper
Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

(1) unsurveyed block

Kalanaman River (2) 6 in (PT. NKU, oil palm) (1.40 0.9 1.9 50% 38 80
8,442
ind/km2, BOSF 2014)

Fragmented landscape 0.9 1.9 10% 26 54

28,403
Sebangau
5943 6222
514,548
(i) ca. 5,800 individuals pre-fire in
495,000 ha (BNF, extrapolation
from monitoring surveys in the
485,017
Sebangau NP + LLG, 2015)
(including 100% 5683 5826
surrounds (ii) 5826 individuals pre-fire in
426,850 TNS)
568,700 ha (National Park size, not
forest area); (WWF-BTNS survey,
July 2015)
300-400 (BNF surveys 2009,
2.48-3.66 ind/km2, Cattau et al.
Kalampangan + Block 2014) – formerly home to 1,500
2.48 3.66 100% 242 358
C individuals. Forest now burnt 9,778
but many orangutans now living
outside forest area in shrubland

Fragmented landscape 0.9 1.9 10% 18 38

19,753

Rungan River Landscape

1724 2794
372,256

Rungan Barat unsurveyed 0.9 1.9 25% 275 581

122,288
(1) 2.93 ind/km2 Mungku Baru
Ulin Forest (BNF, 2010)
(2) 2.61 ind/km2 Mungku Baru
Rungan Timur KHDTK good kerangas forest (BNF,
1.75 2.61 50% 1364 2034
(Mungku Baru) KHDTK 2016) 155,834
(3) 3.94 ind/km2 Kanarakan
dipterocarp forest (BOSF/Russon,
2005)

Fragmented landscape 0.9 1.9 10% 85 179

94,134

Orangutan Population and Habitat Viability Assessment

Kahayan-Kapuas
1065 2300
399,630
unsurveyed, confirmed present

125
Mangkutup West 0.9 1.9 75% 349 736
2001 51,664
 Habitat Lower Upper Lower Upper
Forest Population Estimate

126
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

Mangkutup East (Sg

unsurveyed, confirmed present 0.9 1.9 75% 164 347
Lading) 24,335

Murui - Timpah unsurveyed 0.9 1.9 50% 53 112

11,829
Block B (S of Main
unsurveyed, confirmed present 0.9 1.9 75% 76 161
Canal) 11,266
2.15 ind/km2 in good habitat;
reducing to 0.5 ind/km2 in lower
Bawan 0.9 2.15 50% 190 453
canopy areas (BNF 2010, Bawan 42,142
research area )

Sungai Murui Hulu unsurveyed 0.9 1.9 10% 169 356

187,556

Fragmented landscape 0.9 1.9 10% 64 135

70,838

Kapuas-Barito (Mawas)
2000 3096

Orangutan Population and Habitat Viability Assessment

603,779

2,070 (BOSF/Zurich 2002-03

Mawas (Block E) 0.9 1.23 100% 1514 2070
aerial+ground surveys) 168,203

400 (BOSF/Zurich 2002-03 in

Mantangai (Block A) what was then 40,000 ha), highly 0.9 1.9 100% 104 220
11,555
fragmented & burnt since
no info on habitat or status or OU
Barito Tengah
population. Absent or rare in CA
(Timpah- Buntok-
Pararawen (probably location of 0.9 1.9 10% 331 699
Muara Teweh- 367,692
CA Pararaum mispelled in 2004
Purukcahu-Seihanyu)
PHVA)

Fragmented landscape 0.9 1.9 10% 51 107

56,329
Barito Timur
144 307
101,255

Sungai Sirau (Central Presence confirmed (FORINA/TNC

0.9 1.9 75% 98 206
Kalimantan) 2013; BNF/UMP 2016) 14,450
 Habitat Lower Upper Lower Upper
Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

Hulu Sungai Utara-

1.95 ind/km2; 10-15 OU in 600 ha
Tabalong (South 0.9 1.95 100% 37 81
(FORINA, 2016) 4,135
Kalimantan)
reports of presence, other reports
0.9 1.9 10% 9 20
Buntok of absence 10,534

Fragmented landscape no information on presence 0 0 10% 0 0

72,136
Upper Kapuas
0 0
Swamps
Siawan-Belida
0 0
176,476
rare-absent (i) 2 nests in 4 km
(YIARI/BNF 2012), (ii) absent, FFI
Siawan Belida 0 0 10% 0 0
(2012) (iii) 25 nests in 2km (Erman, 69,803
2003)
Danau Tang - Danau
27 nests in 4.6 km (Erman, 2003) 0 0 10% 0 0
Selogan 34,892

Fragmented landscape 0 0 10% 0 0

71,781
Muller Schwaner 8432 12462
Arabela-Schwaner
8432 12462
6,734,817
(1) 675 in PT. Suka Jaya Makmur
(PT. SJM, timber), 170,500 ha
(WWF, 2011-12)
(2) 528 in PT. Wanasokan Hasilindo
(PT. WH, timber), 46,962 ha (WWF,
2014)
(3) 25-30 in PT. Permata Sawit
Rongga-Perai Mandiri (oil palm), 6,500 ha (0.86 0.75 1.5 25% 2634 3815
870,897
ind/km2, YIARI/BNF, 2014)
(4) Bukit Rongga - unsurveyed
(5) Bukit Perai - 230 in 20,000 ha
(1.12 ind/km2, FFI, 2008)

Orangutan Population and Habitat Viability Assessment

(6) Kerabai - Bahana (0.46 ind/
km2, BNF 2003)
(7) Tanjung Bunga - unsurveyed

127
128
Habitat Lower Upper Lower Upper
Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

(1) recorded present in PT Wana

Kayu Batu Putih (PT. WKBP, timber),
(FFI, no survey details)
(2) 99 in PT Sari Bumi Kusuma
- Delang concession (PT. SBK,
timber), 60,500 ha (2.18 ind/km2,
WWF, 2015)
(3) 771 in PT. Amprah Mitra Jaya
(PT. AMJ, timber) and PT. Karda
Arabela (Arut- Trades (PT. KT, timber), 142,000 ha
0.75 1.5 50% 2698 3526
Belantikan) (1.5 ind/km2, Yayorin/Forina 2015) 483,039
(4) 23 in PT. Sawit Mandiri Lestrai
(PT. SML, oil palm), 10,000 ha
(0.23 ind/km2, BOSF, 2014)
(5) 5 in PT. Pilar Wana Persada (PT.
PW, oil palm), 1,000 ha (BOSF,

Orangutan Population and Habitat Viability Assessment

2011)
(6) 972 in PT. Trisetia Intiga (PT. TSI,
timber) 48,750 ha (2.93 ind/km2,
BOSF 2014)
(1) South-west of Tumbang Manjul
- no recent surveys. Previously high
densities.
(2) mean 1289-1638 in PT Erna
Djuliawati (PT. ED, timber),
160,000 ha, [0.63 ind/km2, WWF
2016 (867-1189 individuals), 1.31
Seruyan Hulu 0.75 1.5 25% 2403 3837
ind/km2, BNF 2016 (1711-2088 883,002
individuals); mean 0.97 ind/km2]
(3) 30 in PT Sari Bumi Kusuma -
Nanga Nuak concession (PT. SBK
timber), 144,700 ha, (WWF 2013)
(4) Seruyan - Sampit - Katingan,
unsurveyed
 Habitat Lower Upper Lower Upper
Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

(1) few Bukit Raya - Bimban region

of TNBBBR - (i) 5 nests in 4 km
(BOSF 2015); 30+ orangutans
reintrouced by BOSF on Sg.
Bimban; (ii) Kuluk Sepangi region
of TNBBBR - 6 OU (BTNBBBR
2012); Batu Panahan - 2 OU
(BTNBBBR 2012)
(2) absent PT. Dwima Jaya Utama
(PT. DJU, timber) - west of Sg.
Samba, ca. 80,000 ha, (0 ind/km2,
WWF 2015; 0.08 ind/km2, BNF
2004)
Samba - Kahayan hills (3) 63 OU in PT. Dwima Jaya Utama
0.5 1 10% 517 1034
(Eastern Schwaner) (PT. DJU) - east of Sg. Samba, ca. 1,034,175
80,000 ha (WWF, 2015); >300 OU
(1.18-1.59 ind/km2, BNF 2004)
(4) rare in PT Carus Indonesia (PT.
CI, timber) - 72,000 ha (3 OU,
WWF 2014); 40 nests/ 5 km (BOSF,
2009)
(5) Kahayan Hulu (PT. Domas Raya)
- unsurveyed
(6) Kapuas Murung Hulu - largely
unsurveyed; 33 nests in 3.5 km
(1.5 ind/km2, Tanjung Niok,
BOSF 2009), 27 nests in 4.7 km
(Tumbang Beronang, BOSF 2009)
(1) rare Bukit Baka - Belaban region
of TNBBBR - (i) 7 nests in 8 km
(YIARI/BNF 2013), (ii) 7 nests in 5.5
km (UNAS 2012) (iii) 44 nests in
7.5 km (0.60 ind/km2, BNF 2003)
(iv) 7-27 OU (BTNBBBR 2012-2016)
Melawi Catchment 0 0 0% 30 50
(2) absent Bukit Baka - Rantau 680,761
Malam region of TNBBBR; 10+ OU
reintroduced by YIARI

Orangutan Population and Habitat Viability Assessment

(3) Upper Melawi catchment &
southern slopes of Madi Plateau,
unsurveyed

129
130
Habitat Lower Upper Lower Upper
Forest Population Estimate
Regional Unit Habitat Unit Area (Ha) Density Density CONFIDENCE Population Population
Landscape (workshop) & Survey Details
(GIS) estimate estimate estimate estimate

(1) HL Bukit Batikap: >160 OU

reintroduced since 2012 (BOSF) in
32,000 ha lowland valley
(2) Rekut - Sg. Banana: 75 OU
reintroduced 2008-2010 (BOSF)
(3) Joloi - Busang - Murung -
Maruwai - Ratah, essentially absent
Murung Raya (average 1.0 nests/km = negligible 0 0 0% 150 200
2,297,138
density, BOSF 2008-2012) but
many areas presumed ecologically
suitable e.g. Maruwai, Busang
Hulu, Sg. Burak, Ratah Hulu
(4) CA Sapat Hawung - absent.
Population recorded as >500 in
2004 PHVA but this erroneous

Orangutan Population and Habitat Viability Assessment

largely unsurveyed, presumed
Kapuas Hulu 0 0 0% 0 0
absent (ecology/hunting) 485,574