New World Warblers (Parulidae)

Black-throated Grey Warbler (Dendroica nigrescens) - HBW 15, p. 751

French: Paruline grise German: Trauerwaldsänger Spanish: Reinita Gris

Taxonomy: Sylvia nigrescens J. K. Townsend, 1837, no locality = vicinity of Fort William, near Portland, Oregon, USA.
Closely related to the superspecies formed by D. chrysoparia, D. virens, D. townsendi and D. occidentalis; probably split off from this prior to initial Pleistocene glaciations and before the four allospecies within it evolved. Hybridization with D. townsendi and with D. occidentalis reported. Race halseii considered invalid by some authors, although nucleotide-sequence divergence between the two races is similar to that between D. townsendi and D. occidentalis. Two subspecies generally recognized.

Subspecies and Distribution:

nigrescens ( J. K. Townsend, 1837) - breeds SW Canada (S British Columbia) S on coast and in coastal mountain ranges of W USA to N California; migrates to wintering areas mainly in W Mexico (S Sonora S to Oaxaca).
halseii ( Giraud, 1841) - breeds in W USA E of the Cascades (from Washington and Wyoming S to California and New Mexico) and extreme NW & N Mexico (N Baja California, extreme NE Sonora); most migrate to W Mexico (including S Baja California).