Migration
of birds
Presented by Aditi and Abhinandana.
What is migration?
Contents Types
Causes
Guiding mechanism in
Birds Navigation
WHAT IS
MIGRATION?
In birds, migration means two-
way journeys—onward journey
from the ‘home’ to the ‘new’
places and back journey from the
‘new’ places to the ‘home’.
This movement occurs during the
particular period of the year and
the birds usually follow the
same route.
Types of
Migration
SEASONAL
MIGRATION
Seasonal migration is the most common form of bird movement.
It involves short (just a few miles) to very long (thousands of
miles) distance movements that see birds travel across varied
landscapes, often moving between different countries,
continents, and even hemispheres.
ALTITUDIAL MIGRATION
The altitudinal migration occurs in mountainous regions. Many birds inhabiting the
mountain peaks migrate to low lands during winter. Golden plover (Pluvialis) starts from
Arctic tundra and goes up to the plains of Argentina covering a distance of 11 250 km
Birds migrate either in flocks or in pairs. Swallows and storks migrate a distance of 9650
km from northern Europe to South Africa. Ruff breeds at Siberia and travels to Great
Britain, Africa, India and Ceylon thus travelling a distance of 9650 kilometers.
Irregular Migration
When some of the birds disperse to a short or long distance for safety
and food, it is called vagrant or irregular migration. Herons may be the
example of vagrant or irregular migration.
Other examples are black stork (Ciconia nigra), Glossy ibis (Plegadis
falcinellus), spotted eagle (Aquila clanga), and bee eater (Merops
apiaster).
Latitudinal migration
The latitudinal migration
usually means the
movement from north to
south, and vice versa.
Most birds live in the land masses of the
northern temperate and subarctic zones
where they get facilities for nesting and
feeding during summer. They move
towards south during winter.
Causes
Seasonal variation
Light
Scarcity of food and day length
Instinct and Gonadal changes
GUIDING MECHANISM IN
BIRDS
Birds can use the Sun’s position in the sky to navigate, although this requires a
grasp of time. As the sun (appears to) shift from the east to the west, birds must
use their internal clock to adjust and stay on course.
Birds are thought to detect magnetic direction with their eyes and magnetic
intensity using receptors in the region of their beak, and both are useful for
orientation and navigation.
These nocturnal migrants navigate by observing the stars in the night sky,
although some stars are more important than others.
Birds can use familiar landmarks as reference points during migration, a
navigational system that relies on both vision and memory.
Thank
you!!
