A Brief History of the Golden-winged Warbler: Part I

Posted May 12, 2025

Topics: Natural HistoryMuseum Collections

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The Golden-winged Warbler’s black chin and eye mask, bright golden crown and wing coverts, white belly, and clear bluish-gray upperparts make it a striking and unmistakable sight. In the summer months their buzzy song can be heard in northern portions of the Great Lakes states and southeastern Canada, and at higher elevations of the Appalachians. Their overwintering range is less well known, but they have been reported in Belize, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, Panama, Columbia, and Venezuela. If you’re lucky, here in Ohio you may see one during spring migration in late April to early May, or fall migration in late August and early September. They use their sharp, tweezer-like beaks to pry open flower and leaf buds for caterpillars hiding within, for which their genus – Vermivora, “worm eating” – is named. The only other species in this genus are the Bachman’s Warbler (now presumed extinct), and the Blue-winged Warbler.

The Golden-winged Warbler is among the most vulnerable songbirds in the world, having undergone a precipitous decline throughout its range, particularly over the last 100 years. The reason behind this decline is an area of ongoing study, and the species is currently listed as Near Threatened.

But it is impossible to tell the story of the Golden-winged Warbler without the Blue-winged Warbler, as their past and futures are inextricably linked.

Not long ago in their evolutionary history – 1.54 million years or so¹ – these two species were one. (In geologic time, this is like last week). What caused their ancestral species to split into two is uncertain, but there are several theories and possible scenarios. One – via what’s called allopatric speciation – is that some individuals may have been blown off course during spring migration and were able to breed in a suitable patch of habitat separate from the ancestral population. Their offspring would have returned to their place of birth to continue the cycle, as their descendants do today. The newly founded population would not have been able to mix with the ancestral one either by distance or a physiographic feature (mountains, water, or habitat they found unsuitable for breeding), or a combination of both.

Millennia marched on, glaciers advanced and retreated multiple times, and the two populations developed different markings and different songs – evolving along their own trajectories and responding to selection pressures unique to their environments.

Then – not so long ago – European colonization began on the North American continent.

The Blue-winged Warbler and Golden-winged Warbler were first described in 1760 by English naturalist George Edwards, “the father of British Ornithology”, in Volume II of his series, “Gleanings of natural history: exhibiting figures of quadrupeds, birds, insects, plants &c., most of which have not, till now, been either figured or described”². These volumes featured detailed copper plate prints and text descriptions of animals and plants. Some illustrations were made from live animals in menageries, but most were made from specimens – either study skins (“preserved dry”), or sometimes whole animals preserved in wine or spirits – shipped to his residence in London from colleagues in the Colonies and elsewhere.

Many North American bird specimens – including those of the Blue-winged Warbler and Golden-winged Warbler – were collected, prepared, and sent to Edwards by his obliging friend William Bartram of Kingsessing, Philadelphia, Pennsylvania. William was the 17-year-old son of John Bartram, the King’s Botanist to the southern colonies. Many of the birds that Edwards depicted from William’s specimens in his Volumes were the first descriptions ever made of those species.

Young William Bartram would follow in his father's footsteps to become the first American-born artist & naturalist, and later author the volume shorthanded as “Bartram’s Travels”, a journal-style account of his 2-year expedition in the newly minted Southeastern United States. It is one of the most prominent American natural history works from that time, containing vivid and detailed descriptions the flora, fauna, weather, and countryside as well as the people he met. A copy of the physical book is at the Ohio History Center Archives & Library, its record is here.

In letters accompanying the specimens, William Bartram wrote of the Golden-winged Warbler (which Edwards named the “Golden-winged Fly-catcher”): “in the month of April they appear in Pennſilvania, where they are only paſſengers to the northward, being ſeen with them but for a few days: they are obſerved to feed on inſects”.

The Blue-wing on the other hand (mistook by Edwards as the Pine-Creeper) was a summer resident: “Mr. Bartram ſays, they arrive in Pennſilvania from the ſouth in April, and feed upon the inſects they find on the leaves and buds of trees, and continue with them the greateſt part of the ſummer; and he believes they breed there, though he never found any of their neſts.”

From other early accounts like Edwards’, it appears that in the early days of the Colonies, the Golden-winged Warbler (then named Helminthophaga chrysoptera) generally occupied the upper elevations of the Appalachians, and southern portions of the upper Midwest and Great Lakes states. These may have formed two separate populations, as they do today, but it’s not certain. The Blue-winged Warbler however (then named Helminthophaga pinus) occurred south and west of and at lower elevations surrounding the Appalachians. Both species have similar habitat preferences for breeding: early-successional forest (in other words, old fields that have been overtaken by youngish trees and dense shrubs and undergrowth). Golden-wings are more specialized, preferring swampier conditions and higher elevations, while Blue-wings are more adaptable and will use later stages of successional forest.

A copy of Jared Kirtland's 1938 Report on the zoology of Ohio (extracted from the Second annual report on the geological survey of the state of Ohio) is at the Ohio History Center Archives & Library, its record is here.

Wheaton lists both species in his 1861 Catalogue of the Birds of Ohio⁴, but provides no further details about their natural history. In his Report of the Birds of Ohio⁵ 18 years later, Wheaton states that the Golden-winged Warbler continued to be a “rare summer resident” and “the rarest of the genus breeding with us, and… the rarest at any time… usually found in swampy places, where the nest is built on the ground, frequently under the broad leaf of the Skunk Cabbage (Simplocarpus foetidus).” By contrast, the Blue-winged Warbler by then had become “a rather common summer resident from May 1^st to September 1^st… a bird of the most retired woodland and swamps… often found on high ground, but usually in the vicinity of water.”

The Golden-winged Warbler was seemingly never common in Ohio. Jared P. Kirtland provided the first recorded report on Ohio birds³ in 1838. Of the golden-wing he writes: “[it] is one of the most delicate and showy of the genus, as well as among the most rare. I captured a few in May last, on the verge of a cranberry-marsh. It is only a transitory visitor in Ohio.” Of the Blue-wing he states, “I have obtained only one specimen of this delicate warbler, and remain ignorant of its habits.” Kirtland was a prominent and active ornithologist, so this admittance seems to suggest the Blue-winged Warbler was also not common in Ohio at this time.

Something in Ohio changed in the mid-19th century that made the Blue-wing go from apparently uncommon to common within a span of 40 years; but what?

Then, in the early 1870s, two new warbler species were found in the United States: the White-throated Warbler (Helminthophaga leucobronchialis) and the Lawrence’s Warbler (Helminthophaga lawrencii).

The first reference of these new species in the context of Ohio were made by Wheaton in his 1879 Report⁵. He states, “Two members of this genus have, within a few years, been discovered in the Eastern States, and may be looked for in Ohio.” At the time, the White-throated Warbler was known by less than a dozen specimens from Massachusetts, Connecticut, New York, and Michigan; Lawrence’s Warbler had only been reported New Jersey and was known from a single mounted specimen collected in 1874. These new warbler species were quite variable in appearance and very similar to Golden-winged and Blue-winged Warblers, not only visually, but their songs as well.

It wasn’t long before naturalists noticed something else that was odd: in areas where their ranges overlapped, Golden-winged Warblers and Blue-winged Warblers were forming mated pairs not only with the newly-described White-throated and Lawrence’s Warblers, but with each other as well!

The appearance of these two new species and the hybridizing of two well-known species caused a fair bit of consternation and befuddlement among the naturalists of the time. Some believed the White-throated and Lawrence’s Warblers were “offshoots” or “mutants” of the Golden-wing and Blue-wing; others felt this was unlikely, and theorized that perhaps the Blue-wing and Golden-wing were merely northern and southern varieties of the same species.

After exhaustive examination of a dozen specimens each of White-throated and Lawrence’s Warblers, quite early on, in 1881 William Brewster (for whom the White-throated Warbler was then renamed the “Brewster’s Warbler”), wrote⁶:

“Only one possible solution remains: — that they are hybrids between [the Blue-winged Warbler] and [the Golden-winged Warbler]. And in support of this view an additional fact may be pointed out; viz., that nearly all the known specimens have been taken within an area where both these species breed, either together, or in close proximity. The very different combinations of markings and coloring in the two hybrid forms, as restricted, is unquestionably due to a reversal of the parents in each case.”

Despite this endorsement from a prominent ornithologist, the controversy continued. Oologist William Dawson in his 1903 book The Birds of Ohio⁷claims the matter unresolved: “The status of [the Brewster’s Warbler] is not yet fully determined. It may be a color phase of [the Blue-wing] or a hybrid between [the Blue-wing] and [the Golden-wing], or possibly a nascent species. Certain it is that its affinities are strongly with [the Blue-wing].” Frank Chapman pushed back on this lack of consensus in his 1907 book The Warblers of North America⁸, stating: “a strong argument for the theory of hybridity among these Warblers is that they have been found breeding only where their ranges overlap.”

In 1911, Walter Faxon gave a detailed report⁹ in which he followed two families of male Golden-wings mated with female Brewster’s. (This charming account is well worth the read and can be found here; a similar account is given by Carter 1923¹⁰.) He gives a 20-page summary of all other such unions reported up to that point by others, including rigorous and exhaustive descriptions of the parents and their offspring, and detailed analyses of the possible modes of inheritance for their traits. He concludes:

“Since [Brewster’s Warbler] was first described by Mr. Brewster in 1874, almost every conceivable hypothesis has been advanced by one writer or another… [a]nd yet it remains one of the most perplexing of ornithological problems. [Brewster’s Warbler] was at first treated as a valid species, but its rarity, its association with [the Blue-winged Warbler] or [the Golden-winged Warbler], its intergradation with one or the other of these species… by a series of intermediate forms, the peculiarity of its distribution, and the fact that it possesses no peculiar characters which are not found in either one or the other of the two species mentioned, led soon and inevitably to the theory that it is nothing else than a hybrid produced by the union of [the Blue-winged Warbler] and [the Golden-winged Warbler]." To drive this home, he adds, "Mr. Brewster himself was one of the earliest advocates of this theory and he has consistently adhered to it up to the present time.”

The complex inheritance patterns of the species' traits had muddied the issue, but after decades of dedicated field observations, specimen collecting, and scholarly debate, the conclusion was inescapable: hybridization was occurring between these 2 apparently closely related species, and it had created a constellation of viable hybrid phenotypes. Stranger still, the hybrid Brewster’s and Lawrence’s Warblers rarely (only two recorded instances at that time) formed mated pairs with each other. A 6-year-long investigation of one small territory in New Jersey in the 1920s revealed that even with an abundance of other hybrids to choose from – if they paired up at all – hybrid warblers chose Golden-winged or Blue-winged Warblers for mates¹¹.

Not only that, but the range of the Golden-wing was shifting northward. And where the Golden-winged Warbler went, the Blue-winged Warbler did not take long to follow.

What was going on??

Stay tuned for A Brief History of the Golden-winged Warbler, Part II!

References

[1] Lovette, I. J. and Bermingham, E. 2002. What is a wood-warbler? Molecular characterization of a monophyletic Parulidae. The Auk, 119(3), 695–714. https://doi.org/10.1093/auk/119.3.695

[2] Edwards, George. 1760. Gleanings Of Natural History, Exhibiting Figures Of Quadrupeds, Birds, Insects, Plants &c., Most of which have not, till now, been either Figured or Described. Part II. Royal College of Physicians, Warwick Lane, London. https://archive.org/details/gleaningsnatura6edwa/page/n7/mode/2up

[3] Kirtland, Jared P. 1838. Report on the zoology of Ohio. Extracted from the Second annual report on the geological survey of the state of Ohio, by W. W. Mather, Columbus. https://archive.org/details/reportonzoology00kirt/reportonzoology00kirt/page/182/mode/2up

[4] Wheaton, John M. 1861. Catalogue of Birds of Ohio. Ohio Agricultural Report for 1860, pp 359-380. Prepared with assistance of Messrs. John Kirkpatrick, R. K. Winslow, and Dr. J. P. Kirtland. https://ia903205.us.archive.org/19/items/catalogueofbirds00whea/catalogueofbirds00whea.pdf

[5] Wheaton, John M. 1879. Report on the birds of Ohio. Geological Survey of Ohio Vol 4: Part I: Sec 2. https://archive.org/details/ReportOfTheGeologicalSurveyOfOhioVolume4Part1/page/n251/mode/2up

[6] Brewster, William. 1881. On The Relationship of Helminthophaga leucobronchialis, Brewster, and Helminthophaga lawrencei, Herrick; With Some Conjectures Respecting Certain Other North American Birds. Bulletin of the Nuttall Ornithological Club, 6(4), 218–225. http://www.jstor.org/stable/24723554

[7] Dawson, William L. 1903. The birds of Ohio; a complete scientific and popular description of the 320 species of birds found in the state. Columbus, Wheaton Pub. Co. https://books.google.com/books?hl=en&lr=&id=f1QaAAAAYAAJ

[8] Chapman, Frank M. 1907. The warblers of North America. D. Appleton. https://books.google.com/books?id=eNA-AAAAYAAJ

[9] Faxon, Walter. 1911. Brewster’s Warbler. Harvard University Museum of Comparative Zoology. https://archive.org/details/brewsterswarbler00faxo/page/56/mode/2up

[10] Carter, T. Donald, & Howland, R. H. 1923. A Brewster’s Warbler and His Brood. The Auk, 40(3), 423–430. https://doi.org/10.2307/4074549

[11] Carter, T. Donald. 1944. Six Years with a Brewster’s Warbler. The Auk, 61(1), 48–61. https://doi.org/10.2307/4079596

By Erin Cashion, Curator of Natural History

Catalog number N 11948. Collected July 10 1930 in Wayne Township, Ashtabula County, Ohio, by Lawrence E. Hicks. Specimen includes the original handwritten collection note.

A male Golden-winged Warbler, Vermivora chrysoptera. Photo by Chrissy McClaren and Any Reago (flickr user Wildreturn). https://creativecommons.org/licenses/by/4.0/

A male Blue-winged Warbler, Vermivora cyanoptera. Photo by Chrissy McClaren and Any Reago (flickr user Wildreturn). https://creativecommons.org/licenses/by/4.0/

The above images were taken from George Edwards' 1760 volume Gleanings Of Natural History, Exhibiting Figures Of Quadrupeds, Birds, Insects, Plants &c., Most of which have not, till now, been either Figured or Described (Part II). Royal College of Physicians, Warwick Lane, London.

The above images were taken from George Edwards' 1760 volume Gleanings Of Natural History, Exhibiting Figures Of Quadrupeds, Birds, Insects, Plants &c., Most of which have not, till now, been either Figured or Described (Part II). Royal College of Physicians, Warwick Lane, London.

Then, in the early 1870s, two new warbler species were found in the United States: the White-throated Warbler (Helminthophaga leucobronchialis) and the Lawrence’s Warbler (Helminthophaga lawrencii).

Taken from Frank Chapman's The Warblers of North America, 1907

From Dawson, William L. 1903. The birds of Ohio; a complete scientific and popular description of the 320 species of birds found in the state. Columbus, Wheaton Pub. Co.

Above: Faxon’s drawings of an adult male Brewster’s Warbler and 3 hybrid offspring in juvenile plumage. Faxon is using an alternative genus name, Helminthophila, meaning roughly "worm loving". From Faxon, Walter. 1911. Brewster’s Warbler. Harvard University

What was going on??

References

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