Townsend's Warbler    Dendroica townsendi

Migratory Status: Neotropical migrant

PIF Population Estimate: 12 000 000

Percent of western hemisphere population breeding in boreal forest: <25%

BAM Effective Detection Radius (m) : 175.51

PIF Maximum Detection Distance (m) : 80

Canadian BBS Population trend: -0.2 n.s. (-1.5 to 1.1)

Life History

Townsend’s Warbler is a 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 considered a single species). It includes three closely related species: the Golden-cheeked Warbler, D. chrysoparia; Hermit Warbler, D. occidentalis; and Black-throated Green Warbler, D. virens, and possibly a more distant relative, the Black-throated Gray Warbler, D. nigrescens. The complex apparently speciated from ancestral populations during several periods of allopatry, that is, when populations became geographically separated and unable to interbreed over a period of time. In this case, the speciation is largely believed to coincide with Pleistocene glacial periods.

Like other members of this superspecies the Townsend’s Warbler has a striking and distinctive plumage, with a bold combination of yellow, black, and olive green body feathers, plus two bright white wing-bars and white outer tail feathers. Although most similar to the Black-throated Green Warbler, the Townsend’s Warbler has a black cheek patch and crown and white ventral region as characteristic identification features.

The breeding range extends from east-central Alaska, south to the mountains of western Montana, Idaho, and Oregon. The species also occurs from coastal British Columbia, including the Queen Charlotte Islands and Vancouver Island, east to the Rocky Mountains in south-western Alberta. In winter there are two distinct populations: the first extends from coastal south-western British Columbia to Baja California; the second population extends from northern Mexico, south to Costa Rica. Separate wintering populations also exist in parts of southeast Arizona and southwest Texas.

Reference(s)

Wright, A. L., G. D. Hayward, S. M. Matsuoka and P. H. Hayward. 1998. Towsend's Warbler (Dendroica townsendi), 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/333