Costa's Hummingbird look-alikes

Key differences

Male Anna's has a rose-red gorget and crown, whereas male Costa's has amethyst-purple. Female Anna's is slightly larger and often shows more extensive green on the flanks and a more prominent white line behind the eye. Female Costa's is generally smaller and paler below.

Key differences

Male Black-chinned has a black chin with an iridescent violet-purple band below it, lacking the extensive purple crown and flared gorget of the Costa's. Female Black-chinned has a longer, more noticeably decurved bill than female Costa's and often shows a faint dusky streaking on the throat.

Key differences

The Calliope is smaller and has a shorter bill. Male Calliope has a streaky magenta gorget that does not extend to the crown or flare out like the Costa's. Female Calliope has a shorter tail and often shows rufous on the flanks and at the base of the tail feathers, which is absent in Costa's.