Anna's Hummingbird

Anna's Hummingbird
(Calypte anna)
The movements of Anna's Hummingbird after the nesting season can take it far beyond the limits of its breeding range. A vagrant Anna's may show up anywhere in the United States in the fall and winter. In recent years, they have become increasingly frequent visitors from southeast Alaska south along the coast to Mexico, and they may be fairly common in the desert areas of southeast California, southern Arizona and southwest New Mexico. In California, where they are most abundant, they move to areas where plants that are coming into bloom will provide food. Often, this results in an altitudinal change in range, with birds moving into higher altitudes following the breeding season, and shifting to lower levels in the fall as temperatures drop. The Anna's Hummingbird is the only hummingbird with a winter range primarily in the United States.

As is the case with other hummingbird species, male and female Anna's Hummingbirds associate only long enough for copulation. Responsibility for construction of the nest and care of the young falls exclusively to the female. During the breeding season, males and females occupy separate habitats. Males establish feeding territories on slopes in open chaparral while females build their nests in bottomlands that include evergreen trees, especially live oaks.

A favorite native food source is red gooseberry (Ribes speciosum), an abundant plant that flowers early in spring, when Anna's Hummingbird begins nesting. It is thought that the plant gooseberry and the hummingbird have evolved together, resulting in Anna's Hummingbirds' unusually early breeding season. Anna's also consumes more insects than any other North American hummingbirds, catching small flying insects on the wing in the manner of a flycatcher, or by hover-gleaning among the leaves and twigs of trees. At other times, they find sustenance at the sap wells of sapsuckers or by pilfering insects from the webs of spiders.

The breeding season begins in December and lasts until May or June. Males arrive first and begin defending territories associated with rich and dependable food sources. Females arrive a few weeks later and establish separate territories; they build lichen-camouflaged nests of made from plant down and spider webs. When the nest is partially built, the male performs his courtship display. First, he hovers before the female, then rises high, sometimes pausing to sing a thin, squeaky warble of a song before again diving toward her, tracing a deep arc and making a loud, explosive noise at the bottom of the dive. Incubation of the eggs takes about two weeks before the naked and blind nestlings hatch. After another three weeks, the young may leave the nest, although they remain dependent upon the mother for food for a few days. Juveniles rapidly develop territorial behavior, sometimes establishing their own feeding territories shortly after leaving the nests.

Physical Description
Average weight: male 4.31 g, female 4.07 g. The Anna's is the largest hummingbird seen on the west coast.

Plumage
Adult male: Metallic green back, dark rose-red crown and gorget, grayish breast.
Adult female: Green back, grayish-white breast, white throat with some red spots, white tips on outer tail feathers.
Juveniles: Young of both sexes look like the adult female, but may have unmarked throats.

Habitat
Chaparral, brushy oak woodlands and gardens.

Distribution
Observed in Alabama, Alaska, Arizona, Arkansas, California, Colorado, Florida, Georgia, Idaho, Kansas, Louisiana, Mississippi, Missouri, Montana, Nevada, New Mexico, Oregon, Tennessee, Texas, Utah, Washington, and British Columbia (resident on Vancouver Island).

Anna's Hummingbird Range Map