Black-throated Blue Warbler Dendroica caerulescens
TAXONOMY:
Order: Passeriformes
Family: Parulidae
Genus: Dendroica
Species: caerulescens
MORPHOLOGY:
Male: Has blue dorsal side (back) and crown. The face, throat, upper breast, and flanks are black. No eye-ring is present. White on lower breast, belly, and undertail coverts, and there is a white patch at the base of the primary feathers.
Female: The dorsal side is brownish-olive and the ventral side is buffy colored. There is a thin buffy-colored eyebrow and right under the eye a buffy-colored crescent.
Immature: Similar to adults; the tail feathers are tapered.
FOOD: Eats insects and seeds, but during the winter eats more seeds (Ehrlich et al., 1988). Males forage high in the trees than the females do (Ehrlich et al., 1988).
MATING SYSTEM: monogamous (Ehrlich et al., 1988).
BREEDING SYSTEM:
Where Breeds: Breeds in deciduous forests and mixed woodlands in the thick shrub layer (Baicicich and Harrison, 1997).
Nest: The nest is found in a small tree or sapling or in a low shrub, evergreen, or rhododendron (Baicicich and Harrison, 1997). The nest is built 1-3 ft. high in a twig fork (Baicicich and Harrison, 1997). The nest is a bulky cup, with a base of bark and twigs, made out of bark strips, moss, dead leaves, and rotten wood fragments, and partly bound by spiders' webs (Baicicich and Harrison, 1997). The nest is lined with hair, black hair-like rootlets, and other fibrous materials (Baicicich and Harrison, 1997). The nest is built by the female in 3-5 days (Baicicich and Harrison, 1997).
Breeding Season: The breeding season begins in late May to early June and ends in early August (Baicicich and Harrison, 1997). This species has up to 3 broods in the north of its range (Baicicich and Harrison, 1997).
Eggs: There are 3-5 eggs laid in a clutch (Baicicich and Harrison, 1997). The eggs are subelliptical to short subelliptical in shape and white to creamy-white in background color (Baicicich and Harrison, 1997). The eggs are speckled cinnamon-brown to brownish-gray which is often concentrated at the larger end of the egg (Baicicich and Harrison, 1997). The average size of an egg is 17 X 13 mm (Baicicich and Harrison, 1997).
Incubation: The incubation period is 12 days and is done by the female (Baicicich and Harrison, 1997).
Nestling: The young, or nestlings, are born altricial and downy, with the down being dark gray in color (Baicicich and Harrison, 1997). The skin is yellowish-flesh color, the mouth is pink, and the gape flanges are pale yellow in color of the young (Baicicich and Harrison, 1997). The young fledge from the nest 10 days after hatching and are tended by both parents while in the nest, but only brooded by the female (Baicicich and Harrison, 1997).
MIGRATION STATUS IN WISCONSIN:
The black-throated blue warbler is a neotropical migrant.
REFERENCES:
Baicicich, P.J. and Harrison, C.J.O. 1997. A Guide to the Nests, Eggs, and Nestlings of North American Birds, 2nd edition. Academic Press: San Diego.
Ehrlich, P.R., Dobkin, D.S., and Wheye, D. 1988. The Birder’s Handbook: A Field Guide to the Natural History of North American Birds. Simon and Schuster, Inc.: New York.
Stokes, D.W. and Stokes, L.Q. 1996. Field Guide to Birds: Eastern Region. Little, Brown and Co.: Boston.
