Vancouver Avian Research Centre

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Species: Black-Throated Gray Warbler Dendroica nigrescens

Description:

This is a striking black, gray and white member of the ‘virens’ group’, 5 species which form a closely related group of warblers. The other species which compromise this group are the Golden-Cheeked, Black-Throated Green, Townsend’s, and Hermit Warblers.
It is an elegant warbler of western North America found and first described by John Kirk Townsend near Ft.William (Portland), Oregon. The Black-Throated Gray was already known there as “Ah Kah a Qual” by the Chinook.
It breeds generally west of the Rocky Mountains from northern Mexico to British Columbia. First arrivals in sw B.C. are usually during the second week of April.

Identification:

General: This is an averaged sized foliage-gleaning wood warbler. It is 11-13 cm long and weighs 7-10 g.

Adult Male: Black head, chin and throat, horizontal white line above eyes and below cheeks; upper parts blue-gray; under parts white with black-streaked sides; two white wing bars; tiny spot of bright yellow in front of eyes(lores).

Adult female: Similar to adult male but black of the head not as dark. The chin is always white and most individuals have a white throat with a band of black across the lower throat and a patch of black at the sides of the rear throat. Yellow lores are not as bright yellow as males.

Juvenile: Black on throat less solid than in adult male. Cheek varies from blackish to slatey brown. Black of crown mostly restricted to sides, center of crown gray. Yellow lores dull yellow.

Similar Species: The general plumage of the males is almost identical to the Townsend’s Warbler. The Townsend’s has greens and yellows rather than black and white. Black and White Warblers may cause confusion, but all Black and Whites show a median crown stripe and lack yellow lores.

Behavior: Watch the Black-Throated Gray foraging, deliberately gleaning and reaching, with occasional hover-gleaning and short sallies.

Habitat: Common in a great variety of woodlands throughout its range, it is home in a wide variety of semi-arid deciduous and conifer woodlands of the western U.S. and southwestern B.C. Most foraging is at mid-level within the canopy.

Information:

This bird tends to be relatively tame and is often readily observed at close quarters as it forages methodically among foliage. Nevertheless, little is known about many aspects of its natural history.
It is a short-to-medium distance Neotropical migrant, and like many such migrants, is insectivorous.
The nest is a deep, compact cup of plant fibers and grasses, bound with spider webs and lined with fir, feathers, and hair. Nests are often placed low (3-10ft.) in bushes, but frequently are placed at 20ft. or more well out on conifer limbs. There are usually 4 white or cream-white, speckled brown eggs.

Conservation Status:

Black-Throated Gray Warbler populations do not seem to have been affected by human activities to any great extent, but changes are difficult to assess because so little is known about this species.
 
Capture Rates


The Black-throated Grey Warbler's preferred habitat is open coniferous or mixed coniferous-deciduous woodland, therefore not seen in high numbers around our banding station. Capture rates (2010-2012; standardized as birds captured per 100 net hours) begin in July and continue through October when activity picks up as juveniles disperse and prepare for their relatively short migration southward.

 

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