The western counterpart of the ruby-throated, the black-chinned regularly pumps its tail. Monotypic. Length 3.3–3.8"; bill 16–22 mm.
Best marks for all ages are narrow inner primaries and blunt primaries. Double-rounded tail. Age/sex differences as ruby-throated except as noted. Adult male: black throat with violet-blue lower band. Adult female: black-violet spots rare on throat. Immature male: Throat usually has black-violet spots.
The black-chinned is often confused with Anna’s and Costa’s, which are chunkier and proportionately bigger headed, shorter billed, and shorter tailed; lack the narrow inner primaries of Archilochus; and molt wings in summer. Female/immature Anna’s slightly larger; underparts more mottled, including undertail coverts (mostly whitish on black-chinned); throat often with rose-red spots; wags tail infrequently. Female/immature Costa’s slightly smaller; face often plainer; wing tips often fall beyond tail tip at rest (shorter than tip on black-chinned). Anna’s call is a smacking chip, Costa’s is a high, tinny tik, both distinct from black-chinned. See ruby-throated.
Indistinguishable from ruby-throated but distinctive male wing-buzz in flight louder (and lower pitched than Selasphorus).
Status and Distribution
Western North America to northwest Mexico. Breeding: common in riparian woodlands, foothills. Migration: mainly March–May, August–September. Winter: Mexico. Rare (mainly October–March) in Southeast; casual in Northeast (fall).
—From the National Geographic book Complete Birds of North America, 2006