Black-throated Blue Warbler
Dendroica caerulescens

Migratory Status: Neotropical migrant

PIF Population Estimate: 2 000 000

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

BAM Effective Detection Radius (m) : 59.41

PIF Maximum Detection Distance (m) : 125

Canadian BBS Population trend: 1.0 n.s. (-1.2 to 3.2)

Life History

The Black-throated Blue Warbler inhabits interior deciduous and mixed-deciduous forests in eastern North America, and requires thick undergrowth for nesting and foraging. Originally considered to be a forest interior species and needing large areas of undisturbed habitat, it is now recognized that this species can also breed in managed forests where understorey habitats have been maintained.

The breeding range extends from north-western Ontario and north-eastern Minnesota, east to Nova Scotia. Southward, this species occurs at higher elevations in New York, portions of New England, and Pennsylvania, extending south throughout the Appalachian Mountains into northern Georgia. Populations overwinter in the Caribbean and along the east coast of the Yucatan and Honduras. Males and females inhabit different habitat niches on their wintering grounds, with males occupying dense tropical forests at lower elevations, and females occupying higher elevation scrub habitats.

The Black-throated Blue Warbler is a striking bird. Males are easily distinguishable from other species by their dark blue tail, back and head plumage, black face, throat and flanks, and white wing and tail spots. Females are markedly different than males - so different that at one point early naturalists thought they were a different species. They are greyish-green overall, with a small white wing spot that may be lacking in first-year birds, and a whitish eye stripe. Adults of both sexes can be readily identified in all plumages by the presence of the bright and diagnostic white wing spot, which some have likened to a “pocket handkerchief”.

The primary song consists of three to seven high pitched buzzy notes that sound like “zoo-zoo-zee” or “zee-zee-zee-zreeeee”, with the last note slurring upwards. This species feeds on insects on the breeding grounds, with fruit and berries added to their diet during migration and on their wintering grounds.

Reference(s)

Holmes, R. T., N. L. Rodenhouse, and T. S. Sillett. 2005. Black-throated Blue Warbler (Dendroica caerulescens), 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/087