The Allen’s Hummingbird is one of the smallest hummingbirds in the North American continent (Long, 1997). This colorful hummingbird averages 7.5 to 9 cm (3.3 – 3.75 in) in length (including its tail) and typically weighs a little over 3 grams (0.11 oz). Its wings measure about 1.5 in. Males tend to be bigger than the females (Long, 1997).
Shared Physical Traits:
The head and back are mostly green. The sides of the head are brown or light brown. The chin and throat vary from bright red to orange with spotted tones ranging from a bronze to silverish.
The underside ranges from a light brown to a cinnamon color. The intensity of this coloration increases towards the abdomen (Long, 1997).
The black bill is long, straight and slim. The legs and feet are dusky. The feet have three front claws and a rear one – suited for perching or locking onto small branches (Long, 1997).
Its tail looks pointy when the bird is perched on a tree-branch. Otherwise, its tail fans out or is forked. Only the female’s tail feathers have white tips; the male’s are dark-tipped (Long, 1997).
The male has a glossy green or bronze-green back and forehead, with rust-colored (rufous) sides and rump (lower back). In some males, the rump is orange.
The male’s throat is also an iridescent orange-red or copper-red, with elongated feathers projecting slightly to the sides. His orangey, pointy tail has dark tips.
The outermost tail feather is very narrow. His wings are dusky-colored and his chest is white. The male has a white spot behind his black eyes.
The female looks similar to the male, but lacks the male’s flashy throat patch, instead her throat is speckled. A few reddish throat feathers may be seen. Other than that, her chin, throat and chest are dull white.
Her upper plumage is mostly green except for the rufous-colored, white-tipped rounded tail. The undertail feathers are pale cinnamon.
The immature bird look like an adult female, but has less spotting on its throat and less rufous on the sides. The young male has more rusty-coloration on the base of its tail.
The female and young Allen’s Hummingbirds are very similar to the widespread, closely related Rufous Hummingbird – specifically the female Rufous. Oftentimes, they are identified by taking into consideration the breeding seasons and ranges of both species.
The male Allen’s Hummingbird can be differentiated from the male Rufous Hummingbird by his green back, while the adult male Rufous Hummingbird‘s back is rusty colored. However, some rare Rufous Hummingbirds have a scattering of green on the crown (top of the head) and back – these are commonly referred to as “green-backed males”.