Lawrence's Warbler

A scrubby successional habitat in Medina County, on a fine morning. I visited this site on June 11, 2025, to seek a very special bird. Letha House Park is part of the Medina County Park District, and it contains a diverse mixture of habitats: old fields, young forest, wetlands, a pond, and most germane to this story, young shrubby thickets.

On April 29, the rare hybrid Lawrence's Warbler was discovered in the very patch in my photo above. The white flowers, by the way, are Smooth Beardtongue (Penstemon digitalis). It wasn't that herb that lured the Lawrence's Warbler, though, it was the mixture of young pole-sized trees and associated brushy growth.

While I can't recall now who found the bird, I think it was Debbie Parker, and/or Joe Wojnarowski. Both reported the bird to eBird on April 29, the first date it was reported. I watched the reports with great interest as time went on but was too busy with various activities to make the trip, although the Lawrence's was reported daily throughout May.

As always, click the photo to enlarge

Finally! June 11 arrives and so does a free and clear day. I hit the road long before sunup and arrived on a beautifully sunny morning with excellent light for photography. I don't think I had even fully exited the vehicle before I heard the hybrid's distinctive buzzy song and soon found the singer in a young sycamore.

The Lawrence's Warbler is a hybrid between the Blue-winged Warbler (Vermivora cyanoptera) and Golden-winged Warbler (V. chrysoptera). The former parent species remains fairly common where appropriate habitat remains, while the latter parent has declined alarmingly across much of its range.

If one uses the Biological Species Concept as a framework for deciding what constitutes a species (as many scientists do), they will be confronted with this tenet: The biological species concept defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance. Although appearance is helpful in identifying species, it does not define species.

Differing visual appearances sometimes have little to do with speciation. Take the Eastern and Western meadowlarks (Sturnella magna and S. neglecta). Most birders would struggle mightily telling those two apart visually. But their songs are different as night and day and with the slightest experience, anyone would instantly recognize them. Those songs probably serve as a primary barrier in limiting contact between the two. There is a narrow band of overlapping range, but even there, hybridization is apparently very rare.

Yet the Blue-winged and Golden-winged warblers look completely different. Anyone would think they were different species with just a glance. And indeed, they are and always have been treated as separate species. But should they?

The Medina County Lawrence's Warbler strikes a pose. I would argue that it is more beautiful than either parent species, or its fellow hybrid the Brewster's Warbler.

About 190 years ago, the legendary frontier ornithologist John James Audubon wrote a letter to his mentor and confidant, John Bachman, in which he speculated that Blue-winged and Golden-winged warblers were the same species. Audubon, a keen observer if there ever was one, no doubt noted mixed pairings and similarities in songs and structure.

It wasn't until 1886 that the inaugural American Ornithologists' Union Checklist of North American Birds appeared, over 50 years after Audubon's prescient Blue-winged/Golden-winged observations noted in his September 15, 1835, missive to Bachman. This checklist is widely considered the standard for North American bird nomenclature. Numerous editions and supplements to the checklist have been published since, but from the first to the current checklist, Blue-winged and Golden-winged warblers have been maintained as separate species. I would note that the scientific name of the Blue-winged changed three times over the checklist's history, and the Golden-winged's twice. English names tend to be far more stable than the ever-shifting landscape of scientific nomenclature.

In the mid-2010's, scientists with the Cornell Lab of Ornithology undertook an intensive study of the genetics of the Blue-winged and Golden-winged warblers. The results weren't very surprising, in my estimation, but provide solid evidence of their genetic similarity. In short, the two "species" are 99.7% genetically identical. Only six regions (0.3%) of the genome reflect distinct differences. This is basically akin to the differences between a human with red hair, and one with blond hair. The Cornall researchers note that the genetic differences between the two groups of Swainson's Thrush (each comprised of three subspecies) are greater than the differences between the two warblers.

When they come into contact, Blue-winged and Golden-winged pairings result in two distinct - and fertile hybrids: the Brewster's Warbler, and Lawrence's Warbler. Brewster's manifests the dominant traits such as the yellow throat and white underparts, while the Lawrence's Warbler manifests recessive traits such as the black throat and yellow underparts. Brewster's hybrids occur more frequently, hence my interest in seeing and photographing the protagonist of this blog post (only the second Lawrence's that I've seen).

The only other member of the genus Vermivora is the now extinct Bachman's Warbler, named for Audubon's confidante and a great naturalist in his own right. That species, which was a specialist of canebrake habitats in the southeastern U.S., is now extinct with the last documented observations dating back to the 1960's.

Blue-winged and Golden-winged warblers have probably long hybridized, and for whatever reasons this species complex never fully separated. Their hybridization may serve them well; in helping the Blue-winged/Golden-winged group (I don't think they should be treated as separate species) adapt to changes in the environment, much of which is man-caused. While the recessive and more fragile Golden-winged group of this species complex may die out (and I certainly hope that it does not!), at least the species in the bigger picture may carry on.

Blue-winged vs. Golden-winged warblers: An interesting conundrum

 

A male Blue-winged Warbler along the Black River in Cheboygan County, Michigan on May 19, 2021. I heard the bird singing, and eventually managed a documentary shot on this dark, rainy day.

I photographed this Blue-winged Warbler in the Pigeon River Country State Forest, which is in the northern tip of Michigan's Lower Peninsula. While the species is old hat to those who live in the eastern U.S., south of Michigan, it's - for now - a rarity up here. In a dozen nearly consecutive years (missed last year - COVID) of intense natural history exploration up here, it is the first Blue-winged Warbler I have documented.

I'm not just missing them. The northern Lower Peninsula is at the northern limits - for now - of the southerly Blue-winged Warbler's distribution. eBird records remain sparse here, and most of them come from the last decade. Records will continue to increase, I am sure, and I am reasonably certain this will not be the last Blue-wing I encounter in this region.

While leading a group a few days after finding the Blue-wing, and only a few miles way from that spot, we encountered the bird above. It is a hybrid between the Blue-winged and Golden-winged warblers, and this hybrid form, which expresses dominant genetic traits of both species, is known as the Brewster's Warbler (At least for now. There is a movement, misguided in my opinion, to do away with all eponymous bird names). I revisited this spot on May 28 and made this shot. The bird was singing a more or less Golden-winged Warbler song, although it frequently elided the last syllable. Lawrence's Warbler is the other typical hybrid form but it is far scarcer. I've only seen it once, long ago. This absolutely stunning form - lemon-yellow below, bluish-gray above, with chickadee-like black bib, and prominent ebony eyeline, apparently results mostly from pairings of second generation backcrosses. Brewster's hybrids express mostly dominant genetic traits of the parent species; Lawrence's expresses recessive traits.

Golden-winged Warblers are reasonably common up here. To show how easy to find they can be, after working with the aforementioned Brewster's Warbler, I drove a few miles north to an aspen-dominated reverting clearcut and found and photographed this apparently "pure" Golden-wing for a hot off the press comparison.

PHOTOGRAPHIC NOTE: I love trying to shoot "creative blur" songbird photos. This fellow sat on this Bigtooth Aspen branch for some time, singing and preening. When songbirds preen, they often interject short violent shakes of their wings, tail, and body. The photographer should be alert for this behavior. As long as the head and eye are in focus, the shake shot will work, and create an interesting pose. Badly done, "creative blur" is just synonymous for a poor photograph. Because of the ample sunlight streaming in over my shoulder, I was stopped down to f/8. Even though my shutter speed was 1/1000 (ISO 320), it still wasn't nearly fast enough to freeze the action and we see the wings and tail in an interesting blurred fluff. Had I been more on my game, I would have probably had the shutter speed down to 1/200, though.

I "fear" I am bearing witness to the beginning of the end of the Golden-winged Warbler in the northern Lower Peninsula. I don't really fear this, though, and am rather more fascinated by the biological process of genetic swamping by the Blue-winged Warbler. When these two "species" come into contact, the process of hybridization commences, with the upshot being that within a few decades all of the Golden-winged Warblers will be replaced by genetically dominant Blue-winged Warblers.

The likely explanation for the prolific hybridization is that the two entities have only recently come into contact with one another. As European settlers opened up the vast eastern deciduous forest, the clearing of the landscape abetted the northern expansion of the more southerly Blue-winged Warbler. As it increasingly came into contact with the northerly breeding Golden-wing, hybridization occurred resulting in the genetic swamping that seems to be increasingly common. In my state of Ohio, the Golden-wings were largely vanquished by the 1940's. About 75-80 years later, I am witnessing this same phenomenon nearly 300 miles to the north of Ohio's Oak Openings region near Toledo, where Ohio's most robust population of Golden-wings was historically documented.

Sharp students of natural history might ask "If they hybridize and produce fertile offspring, why are Blue-winged and Golden-winged warblers separate species?" 

Great question.

"The Biological Species Concept defines a species taxon as a group of organisms that can successfully interbreed and produce fertile offspring. According to that concept, a species' integrity is maintained by interbreeding within a species as well as by reproductive barriers between organisms in different species." (lifted from www.sciencedirect.com).

The BSC is the most common concept that defines species, although genetic analysis and the resultant data increasing play a role in drawing species lines. Genetic studies of these two warblers also do not bolster the case for separate species. They are 99.97% genetically similar. But morphology has apparently won the day, and the two are retained as separate species based primarily on their very different appearances.

WAY back in 1835, John James Audubon speculated that Blue-winged and Golden-winged warblers were the same species. Indeed, it seems that they should be considered forms or subspecies of the same entity. It's possible a bit of politics enters into the decision to retain them as separate species. Can you imagine the hue and cry in the birding community if these two "species" were lumped into one?

Independent of the human obsession with sorting and pigeonholing organisms, and the problems sometimes encountered when doing so, I will continue to enjoy the unfolding drama of the Blue-winged/Golden-winged clash in northern Michigan. Personally, I do not see this as a conservation issue - certainly nothing approaching the true conservation concerns surrounding the nearby breeding Kirtland's Warbler. Rather it is a case of long-term (or maybe short-term!) evolution playing out its hand. The Blue-winged form holds primacy over the Golden-winged form, and who are we to say that this is bad? I suspect Nature knows better than we as to what this "species" needs to expand and flourish.

Golden-winged Warbler serendipity

 

A stunning male Golden-winged Warbler perches in a horseshoe-shaped twig - the best perch in an otherwise cluttered scene.

Last Tuesday, I traveled to Hocking County (Ohio) to meet with Cathy and Paul Knoop about a writing project that Paul wants to take on. It was a great visit capped by a hike around the Knoop's 70-acre property. We saw a bonanza of biodiversity, and maybe I will get around to posting a few especially notable finds later.

I went down really early, to photograph birds beforehand. One of my quick stops was Conkles Hollow State Nature Preserve. I wheeled into the parking lot, not intending to spend much time, and soon saw a few White-crowned Sparrows. I love these dapper, well-dressed sparrows so out came the photo rig. As soon as I had the camera and lens ready for action, a Golden-winged Warbler sang once, from dense cover. A bit of pishing got him to pop from cover, and he gave me a few shots as above, before resuming active foraging. One shot I missed, that would have been awesome, was of the bird doing its acrobatic chickadee-like foraging: hanging upside down from leaf petioles while probing into leaf clusters. Just wasn't quick enough on the draw.

It's always good to actually clap eyes on this species, to ensure that the bird isn't a hybrid. This bird is not, but both Brewster's Warbler and Lawrence's Warbler can sing songs similar to the parent species. Blue-winged Warbler is the other parent. Brewster's is the more frequent of the hybrids, and I've seen it a number of times. The Lawrence's Warbler - which expresses recessive traits of the Blue-winged Warbler and is utterly stunning - would be the grand prize. I've only seen one, and that was many years ago, before I was into photography.

This has been a grand spring for the rare Golden-winged Warbler. Probably a few dozen reports have come from Ohio, the most I can recall since I don't know when. That's good news. Of the 38 species of warblers breeding in eastern North America, this is the third rarest, eclipsed only by the Kirtland's and Swainson's warblers.

Golden-winged Warbler, feeding

A male golden-winged warbler, with brilliant golden ingot stamped across his wing, forages in a choke cherry, Prunus virginiana. I made this image and the following ones a few days ago, while in between groups that I'm leading here at NettieBay Lodge in northern Michigan.

These acrobatic little warblers are not too tough to find up here, and seem especially smitten with cherries in the genus Prunus. A feeding bird will quickly flit about leafy boughs, quickly inspecting leaves and often dangling upside down like a chickadee. The primary reason that golden-wings are probably interested in cherries is due to caterpillars. Prunus is well known for the diversity and numbers of caterpillars that feed on the foliage, and the warblers are adept at ferreting them out.

Read on for a pictorial display of golden-winged warbler foraging technique.

I had secreted myself and my large lens as best I could, after hearing a golden-winged warbler's lazy breezy song along a back road in the Pigeon River Country State Forest. It wasn't long before the bird presented itself - this species is not especially bashful - and I took the opportunity to closely watch the bird as it worked its way through the adjacent choke cherry colony.

Here, the warbler has found a potential treasure concealed in two silked-together cherry leaves, and has plunged its bill in for a better look.

Detecting a tasty larval snack, the bird inserts its long sharp bill, and opens wide. The mandibles act as scissors, prying apart the caterpillar's lair. Just below the bird's bill tips, you can see the whitish cords of silk that the caterpillar used to seal shut its hiding spot.

A second later, the warbler has a tiny but nutritious snack (as always, click the photo to enlarge). The entire operation, from discovery to swallow, took all of about ten seconds. Given the energy and sharp-eyed efficiency of golden-winged warblers, one must wonder how many caterpillars a bird must take in a day. Hundreds, probably.