Bay-breasted Warbler

Setophaga castanea


Early Spring Date: April 29
Late Spring Date: May 27
Most Frequently Seen: May 10-17

Bay-breasted Warblers are one of the most sought-after species at Monticello Park. They are usually uncommon. In 2012, the only sightings during the spring (two birds) were on May 12. But in 2017, they were seen on twelve different days. The first ones were seen on April 29 (the earliest spring date in 13 years), and there was a good chance of seeing one during the third week in May.

Where to See Them in the Park

Bay-breasted Warblers usually stay high in the canopy. Their song is high-pitched and can be difficult to hear. In 2017, they came down lower where they could be seen more easily; not many cankerworms were around, and songbirds had to seek alternative food sources closer to the ground. Bay-breasted Warblers sometimes go into the creek to bathe and drink.

Physical Description


Bay-breasted Warbler Male
Male - photo by Mike Pollack

Bay-breasted Warbler Male
Male - Photo by Carol Jean Stalun

The male Bay-breasted Warbler is a striking bird. The cap, breast, and flanks are chestnut. The face and cheeks are black, and the side of the neck has a large buffy patch. The male has two white wingbars, and the back has black and gray streaks.

Male Bay-breasted and Chestnut-sided Warblers
Male Bay-breasted and Chestnut-sided - Photo by Carol Jean Stalun

No other warbler who visits Monticello has a rufous cap. If you can see only the underside and the chestnut flanks, which often happens when birds are high in the trees, you might confuse a Bay-breasted with a Chestnut-sided Warbler. There is much more chestnut on the flanks of the Bay-breasted, and the Chestnut-sided does not have chestnut on the throat. The underparts of the Chestnut-sided are white, while the undersides of the Bay-breasted are tan. The back of the Bay-breasted is dark, while the back of the Chestnut-sided has a greenish-yellow tinge. The Bay-breasted is one of the larger warblers and looks a little bigger and bulkier. Bay-breasted Warblers generally are seen higher in the trees than the Chestnut-sided.

Bay-breasted Warbler Female
Female - Photo by William Higgins

Not all Bay-breasted Warblers have unmistakable fieldmarks. In the fall, some look so much like fall plumage Blackpoll Warblers that they are referred to as "Baypolls". Spring Bay-breasted Warblers can be difficult to identify. The bird in the above photo is probably a second-year female. Most of the unmistakable fieldmarks of the adult male are lacking, making her plumage very mistakable. She has a faint wash of chestnut on the breast and flanks, but this can be difficult to see in the field. There is no rufous cap, and the buffy mark on the neck does not stand out. Other Bay-breasted Warblers who are not adult males have varying levels of chestnut on their cap, throat, and flanks. The more chestnut is present, the easier the bird will be to identify.

Vocalizations

The song of the Bay-breasted is a weak series of two-note phrases. The similar phrases of the Black-and-white Warbler are not loud, but the song of the Bay-breasted is even softer, as one would expect from a bird who spends a lot of time in the canopy where sound carries well.

Hear the vocalizations of the Bay-breasted Warbler.

Notes

Bay-breasted Warblers breed in the boreal forests of Canada and Northern New England. They are a species whose population rises and falls based on their abililty to find spruce budworms on their breeding grounds. The color "bay" is reddish-brown, and it is used more frequently to describe horses. It is mentioned in the famous old minstrel song "Camptown Races", by Stephen Foster. The song has the lines, "I'll bet my money onde bob-tail nag, Somebody bet on de bay". Camptown is a village in northeastern Pennsylvania.

Origin of Names

Common Names: Bay-breasted from the plumage. The New World Warblers were named for their similar appearance to European warblers, to whom they are not related. Most of the New World warblers do not warble (sing continuously with notes that change frequently).
Genus Name: Setophaga means "moth eating".
Species Name: Castanea is Latin for "chestnut", from the color of the breast, cap, and flanks.

Bay-breasted Warbler video footage

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