Family: TROCHILIDAE (Hummingbirds)

Description

Male Anna's Hummingbirds are easily recognized by their rose-red gorgets and foreheads, though seeing this iridescent structural color in the field depends on the angle between the sun, the bird, and the observer. The remainder of the upperparts are dark glossy green, while the remainder of the underparts are gray, mottled with dull green. Females lack red on the crown, their entire upperparts being green, and have the red on the throat restricted to a small irregular blotch. Females are best distinguished from other similar hummingbirds by their larger size, darker mottled gray underparts, and dry staccato call.

Size: Length around 100 mm; wingspread 114-121 mm; weight 4.0-4.5 grams.

Voice: The male's song is a complex series of scratchy noises, consisting of three groups of phases, which may be repeated for several minutes. Both sexes emit a simple toneless "chip" that readily distinguishes them from other hummingbirds. When the male is displaying, he emits a high-pitched loud "pop" at the bottom of his dive.

Range and Habitat

Range: Originally confined to northwestern Baja California and Upper California west of the Sierra Nevada, Anna's Hummingbird has enjoyed an enormous range expansion over the last 65 years, as it has adapted to urban gardens. It has spread north to Vancouver, British Columbia, east through southern Arizona, and south to Guerrero Negro, Baja California. Nonbreeding vagrants have dispersed even farther, as far southeastern Alaska, Wisconsin, and Florida. Large numbers of Anna's Hummingbirds migrate from California to spend the fall in southern Arizona.

Habitat: Originally, Anna's Hummingbird's habitat was chaparral, especially where the flowers of currant and gooseberry bushes offer a steady supply of nectar. With the proliferation of eucalyptus trees, tree tobacco, and hummingbird feeders, Anna's Hummingbirds adapted readily to urban and disturbed habitats.

Natural History

Behavior: The male Anna's Hummingbird's dive display is commonly thought of as a courtship display but actually is territorial, intended to drive the object of the display out of the territory. In this display, the male flies to a height of 20 to 40 meters, then dives vertically, pulling out of the dive as he passes the recipient, pauses to sing in the air above the recipient, then ascends to repeat the display. If the object of the display is a female, she may be chased until the male shifts to a horizontal display, preceding mating.

Reproduction: Male and female Anna's Hummingbirds come together only to mate; the female alone builds the nest, incubates the young, and rears the brood. The nest is built of plant material bound together with spider webs, then camouflaged on the outside with bits of bark, dead leaves, lichen, or even chips of paint. The clutch consists of two white eggs. Incubation period usually 16 or 17 days; nestling period 18 to 26 days.

Diet: Nectar of a wide variety of flowers, of both native and exotic plants, and tiny insects or spiders, plucked from foliage or taken in mid air. Many native plants on whose flowers Anna's Hummingbirds feed heavily rely on the hummingbird for pollination.