Range: Breeds in Canadian and Transition Zones from northern Minnesota, central Ontario, and northeastern Quebec south to central Minnesota, southern Michigan, southern Ontario, Pennsylvania (mountains), and northern Connecticut; winters from Key West, Florida, to the Bahamas, Greater Antilles, and Cozumel Island.
The male black-throated blue warbler is one of the most conspicuous of the warblers, his black throat and blue back serving to distinguish him at all times and all seasons. The female, despite her inconspicuous coloration, may always be identified by the white spot on the primaries. The bird is common and ranges widely through eastern North America, and few flocks of migrating warblers are without a greater or less number of this species. Though in the main a common resident of the northern woods, in the mountains it breeds as far south as Maryland, while a color variety of the bird (Dendroica cærulescens cairnsi) nests in the southern Alleghenies from Pennsylvania south to Georgia.
Thayer, as quoted by Chapman, says of the song: “There is not a more regularly and amply versatile singer among our eastern warblers than the bIack-throated blue. It has at least four main songs, on which it is forever playing notable variations.”
Whether in its northern or southern home, the black-throated blue warbler builds its nest of bark, roots, and other pliant material, loose and rather bulky, in a variety of saplings, bushes, and weeds, but always a few inches or a few feet from the ground.