Rufous Hummingbird (Selasphorus rufus) and Ruby-throated Hummingbird (Archilochus colubris) look-alikes

Key differences

Very similar to Rufous Hummingbird. Male Allen's has a green back (Rufous has rufous back), though some Rufous males can have green on the back. Females and juveniles are extremely difficult to distinguish; Allen's typically has less rufous on the flanks and tail, and a broader outer tail feather. Range is a key differentiator: Allen's is primarily coastal California and Oregon, while Rufous is more widespread in the west.

Key differences

Males have a rose-pink gorget (Ruby-throated is ruby-red). Females and juveniles are green above, white below, but lack the rufous of Rufous Hummingbirds and have a broader tail. Males produce a distinctive trilling sound with their wings in flight, which Ruby-throated does not.

Key differences

Males have an iridescent rose-pink crown and gorget (Ruby-throated has only a red gorget, Rufous has orange-red gorget and rufous back). Females and juveniles are green above, gray below, and often show some iridescent red on the throat. Anna's is a resident species in much of its range, unlike the migratory Rufous and Ruby-throated.