Black-throated Blue Warbler (Setophaga caerulescens) flight is fast, slightly undulating, and direct with rapid wing beats—a typical warbler flight.
The male and female Black-throated Blue Warblers look so dissimilar that early ornithologists thought they were different species. Many of the females have a blue wash to their wings and tail, and almost all have a subdued version of the male’s white “kerchief,” so identification is not difficult.
This beautiful American species migrates northward in spring, along the eastern flank of the Appalachians, but a small number of birds fly along an imaginary line, northwestward to the Great Lakes. This “line” is so clearly defined that this bird is common in Chicago but extremely rare in St. Louis.
Black-throated Blue Warbler call is a husky junco-like tchunk; flight call is a distinctive, drawn-out, metallic ssiiiink, reminiscent of some Northern Cardinal calls; song is a relatively low-pitched series of slurred buzzes zu zu zu zo zhray zhreee, or slower zhray zhray zhreeee.
Black-throated Blue Warbler nest is a bulky cup of plant material a meter off ground in the dense forest; 3–5 eggs; 1–2 broods; May–August. The feeding behavior of Gleans arthropods, mainly caterpillars, is from the mid-low level in the forest; they take small fruit and nectar. Males are gorgeous year-round, especially when viewed against contrasting fall foliage.
Black-throated Blue Warbler breeds in relatively undisturbed deciduous and mixed hardwood forests from southern Ontario and northern Minnesota to Nova Scotia and into the Appalachians of Georgia. Fall migration through wooded habitats; a Caribbean migrant They spend winters in Central and South America.
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· Length: 5 in. (13cm)
· Wingspan: 7 ½ in. (19cm)
· Weight: 9/32-7/16oz (8-12g)
· Social Migrant: Flocks
· Life Span: Up to 10 years
· Status: least concern
· Order: Passeriformes
· Family: Parulidae
· Species: Setophaga caerulescens
