Vermivora cyanoptera
Order Passeriformes
Family Parulidae
♂ Adult male.— Crown bright yellow; back and rump bright olive-green in strong light; a narrow black line through the eye; wings and tail bluish-gray; wing-bars white or yellowish-white; outer tail-feathers showing white when spread; under parts bright yellow.
♀ Adult female.— Similar, but yellow of head restricted to the forehead; under parts duller.
Nest, on the ground.
Eggs, white, thinly speckled with reddish-brown.
The Blue-Winged Warbler does not occur north of southern Connecticut and the Lower Hudson Valley, but in most of this region it is fairly common. It arrives early in May and leaves early in September. It is found in dry bushy fields, on the edges of woodland, and sometimes even in swampy growth. It is not so active as many of the warblers, and gleans its food leisurely among the branches of trees. Its song is characteristic; the syllables zwee-churr, both notes drawled, represent the ordinary song. It occasionally utters a longer, more complicated series of notes. From the Yellow Warbler it may readily be distinguished by its gray wings and by the black line from the bill through the eye.
Hoffmann – A Guide to the Birds of New England and Eastern New York (1904)