Allen’s hummingbird (Selasphorus sasin) is a species of hummingbird that breeds in the western United States. It is one of seven species in the genus Selasphorus.
Allen’s hummingbird is a small bird, with mature adults reaching only 3 to 3.5 in (76 to 89 mm) in length. The male has a green back and forehead, with rust-colored (rufous) flanks, rump, and tail. The male’s throat is an iridescent orange-red. The female and immature Allen’s hummingbirds are similarly colored, but lack the iridescent throat patch, instead having a series of speckles on their throats. Females are mostly green, featuring rufous color only on the tail, which also has white tips. Immature Allen’s hummingbirds are so similar to the female rufous hummingbird, the two are almost indistinguishable in the field.
