Males: The throat and upper breast is black. The face is yellow with an olive eye stripe and lore. The dorsal side is olive-green. The ear patch is olive color surrounded by yellow. There are white wing bars. The undertail coverts are colored white.
Females: Like the male except throat is yellow and upper breast has less black.
Immatures: the immature male is identical to the adult female. Immature female is paler in color as compared to the adult female, it has a pale colored throat and breast; the immature female also has faint streaking on the side. Immatures of both sexes have tail feathers which are tapered.
FOOD: insectivorous (Ehrlich et al., 1988).
MATING SYSTEM: monogamous (Ehrlich et al., 1988).
PREENING: the black-throated green warbler scratches its head over-wing style (Ehrlich et al., 1988).
BREEDING SYSTEM:
Where Breeds: Breeds in coniferous woodlands or mixed woodlands where conifers dominate (Baicicich and Harrison, 1997).
Nest: The nest is found in conifers, deciduous trees, shrubs, and vine tangles, from almost ground level to 70 ft. high (Baicicich and Harrison, 1997). The nest is a compact, deep cup made out of twigs, bark strips, moss, grasses, and plant fibers, and is lined with hair and feathers (Baicicich and Harrison, 1997). The nest is built by the female in 4 days (Baicicich and Harrison, 1997).
Breeding Season: The breeding season begins from mid-May to early June and ends in late July (Baicicich and Harrison, 1997). The species sometimes has two broods (Baicicich and Harrison, 1997).
Eggs: There are between 4 and 5 eggs laid in a clutch (Baicicich and Harrison, 1997). The eggs are subelliptical to short subelliptical in shape and grayish-white to creamy-white in background color (Baicicich and Harrison, 1997). The eggs are speckled chestnut-red to purplish-brown in color (Baicicich and Harrison, 1997). The average size of an egg is 17 X 13 mm (Baicicich and Harrison, 1997).
Incubation: The incubation is 12 days and is done by the female (Baicicich and Harrison, 1997).
Nestling: The young are born altricial and downy, with the down being dark brown in color (Baicicich and Harrison, 1997). The skin is dark orange, the mouth is pink, and the gape flanges are pale yellow in color (Baicicich and Harrison, 1997). The nestlings fledge from the nest after 8-10 days and are tended by both parents (Baicicich and Harrison, 1997). The eyes open 3 to 4 days after hatching (Baicicich and Harrison, 1997). When the nestlings fledge the parents will divide up the young and care for them until they separate (Baicicich and Harrison, 1997).
MIGRATION STATUS IN WISCONSIN:
The black-throated green 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.