This hummer is a familiar species in West Coast gardens, where it is present year-round. Monotypic. Length 3.5–4"; bill 16–20 mm.
Tail slightly rounded to double-rounded. Adult male: rose (fresh) to orange-red (worn) gorget and crown. Adult female: throat and underparts spotted and mottled dusky to bronzy green, median throat blotched rose-red. Immature male: resembles adult female but upperparts fresher in February to June, with fine buff tips; throat and crown usually with more scattered rose spots; white tail tips narrower. Complete summer molt produces plumage like adult male by late fall. Immature female: resembles adult female but upperparts fresher in February to June; throat often lacks rose spots.
Costa’s smaller (obvious in direct comparison), and males readily identified (beware occasional hybrids, which look more like male Costa’s, sound more like Anna’s). Female/immature Costa’s proportionately longer billed but shorter tailed, often best told by call: high, tinny pit call and twitters distinct from Anna’s. Costa’s generally plainer on throat and underparts, without dusky throat spotting. See black-chinned hummingbird.
Call: a slightly emphatic to fairly hard tik or tih and a more smacking tsik, in flight and perched. In flight chases, a rapid-paced, slightly buzzy twittering, t-chissi-chissi-chissi, and variations. Song: a high-pitched, wiry to lisping squeaky warble from perch, often prolonged and repeated with pulsating succession. Year-round.
Status and Distribution
Western North America to northern Mexico. Breeding: common (December–June) in scrub, gardens, etc. Dispersal/Migration: Some late summer movement upslope to mountains. Local movements complex. Winter: casual (mainly fall and winter) north to Alaska and in the East.
—From the National Geographic book Complete Birds of North America, 2006