Black-throated Green Warbler    Dendroica virens

Migratory Status: Neotropical migrant

PIF Population Estimate: 9 600 000

Percent of western hemisphere population breeding in boreal forest: 50%

BAM Effective Detection Radius (m) : 62.92

PIF Maximum Detection Distance (m) : 125

Canadian BBS Population trend: -3.1 n.s. (-10.5 to 4.4)

Life History

The Black-throated Green Warbler is the most widely distributed member of the Dendroica virens superspecies complex (i.e., a group of closely related species that occur in separate geographic areas and that are too morphologically different to be included in a single species), which includes three closely related species (Golden-cheeked Warbler, D. chrysoparia; Hermit Warbler, D. occidentalis; and Townsend’s Warbler, D. townsendi), and possibly a more distant relative (Black-throated Gray Warbler, D. nigrescens). This group apparently speciated from ancestral populations during several periods of allopatry (occurs when organisms are unable to interbreed because of geographic separation), largely believed to coincide with Pleistocene glacial maximums.

As the highly descriptive name implies, the appearance of the Black-throated Green Warbler is partly self-explanatory. The combination of black throat, black streaked flanks, yellow face with olive auriculars (i.e., feathers that covers the side of a bird's head), and unmarked olive-green crown and back are distinctive, even amongst other members of the superspecies complex.

The breeding range of this bird extends over most of the southern boreal forest, from Newfoundland to east-central British Columbia. The breeding range also extends south into mixed and deciduous-dominated forests associated with the Great Lakes and the Adirondack and Appalachian Mountains. The winter range includes most of southern Mexico, Central America, northern South America, and the larger islands in the Greater Antilles (Caribbean).

Unlike many other North America wood warblers in this genus, the Black-throated Green Warbler does not appear to follow spruce budworm (Choristoneura fumiferana) outbreaks. Therefore, this species does not display the large seasonal population fluctuations attributed to such outbreaks observed in similar congeners.

The species occupies a wide range of habitat types throughout its breeding range, although most often associates with coniferous forests. The species does occur in mixed deciduous-coniferous forest in some portions of the breeding range, though this is limited to more southern locations.

Reference(s)

Morse, D. H., and A. F. Poole. 2005. Black-throated Green Warbler (Dendroica virens), The Birds of North America Online, . A. Poole, Ed. Ithaca: Cornell Laboratory of Ornithology; Retrieved from The Birds of North America Online database: http://bna.birds.cornell.edu/bna/species/055