The Blue-winged Warbler (Vermivora pinus) is one of our rare visitors few get to see. If you ever do find it, you won't forget it because it is so brilliantly yellow. It is a deep medium yellow (cadmium yellow medium for those who paint) and not the cool lemon yellow often seen in many other species found here.
The Blue-winged Warbler is a rare fall visitor found most often in the Grand Manan archipelago and along the east coast. It was first reported here from Machias Seal Island in 1951. The normal range of this species is more southerly. The breeding range is the eastern half of the mid US states extending into the most southerly part of Ontario. These birds winter from southern Mexico to Costa Rica and occasionally south to Panama and the West Indies. They usually migrate at night and are a trans-Gulf migrant.
The Blue-winged Warbler is a challenge to observe because it likes to forage in dense brush and thickets. The only one I have ever seen was on Black Beach Road in the thick alders. Its brilliant yellow looked like a yellow streak as it flew across the road. In the spring the plumage of this species is startlingly beautiful. The males and females are similar with the female being just a bit duller. The male has a yellow head, an olive-green nape, a black eyeline and thin black bill, olive-green back and rump and bluish-grey wings. It has white wingbars and a brilliant yellow breast and belly. The undertail coverts are white and the gray tail shows white spots on the outertail feathers. The legs are dark gray or black. Readers, we are describing a brilliant bird here. The yellow is so bright that one often fails to see the other field marks except for the black eyeline and bluish-gray wings. Considering this species does not give you much time to enjoy its beauty you have to be sharp-eyed to get a good look or photo of this one!
In the photo above note the black eyeline, the white under the tail and on the outer tail feathers. The song of the Blue-winged Warbler is so distinctive the trained birder knows to stop and find what warbler species is making that buzzing sound. That is because we so rarely hear it. The song is a beeee-bzzzz sound with the beeee being high and the bzzzz being low in pitch. The bird also makes a long, high buzz ending with a tsi zee drawn out sound. The call note is a snik sound. This is one species song we should learn from the digital recordings available on the internet because this species is often heard before seeing and undoubtedly is missed because it likes to stay hidden.
The Blue-winged Warbler nests close to the ground in well-concealed grass or blackberry canes or sometimes under a bush. The nest is attached to upright stems of grass or weeds, especially goldenrod. The nest itself is bulky but narrow and deep. It is built by the female of dead leaves, grass, beech or grapevine bark and lined with plant fibres and animal hair. Four to seven white eggs with fine brown spots are laid and incubated by the female for 10 to 11 days. Both adults feed the nestlings which fledge at 8 to 11 days of age. Blue-winged Warblers eat mainly insects and spiders.
What species would you mistake for the Blue-winged Warbler? The Yellow Warbler, the Prothonotary warbler and the Pine Warbler. The Yellow and Prothonotary Warblers do not have the black eyeline. The Pine Warbler is much duller in colour and also does not have the black eyeline. Differentiation should not be a problem in this brilliant species!
Any discussion of the Blue-winged Warbler is not complete without mentioning the fact that it hybridizes with the Golden-winged Warbler where their territories overlap. First generation hybrids are called Brewster's Warblers. These are fertile and will interbreed or will breed back to the Blue-winged species producing the second generation hybrids. These are called Lawrence's Warblers. It took many years to understand these relationships but the hybrid relationships and plumages are now clear. Brewster's and Lawrence's Warblers are interesting but not separate distinct species. We are not likely to see these hybrids here because we have so few Blue-winged Warblers and almost no Golden-winged Warblers. I don't think we have any breeding records of either of these species.
The population of Blue-winged Warblers is expanding northward in the Great Lakes region. Reforestation and thus the loss of open habitat may be a reason. Urban sprawl in the northern US is also a reason for the range expansion but also a reason for declining numbers.
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