Annas hummingbird

Appearance

Anna's hummingbirds are 3.9 to 4.3 in long with a wingspan of 4.7 inches and a weight range of 0.1 to 0.2 oz. They have an iridescent bronze-green back, a pale grey chest and belly, and green flanks. Their bills are long, straight, and slender. The adult male has an iridescent crimson-red, derived from magenta, to a reddish-pink crown and gorget, which can look dull brown or gray without direct sunlight, and a dark, slightly forked tail. Females also have iridescent red gorgets, although they are usually smaller and less brilliant than the male.

The male Anna's hummingbird is the only North American hummingbird species with a red crown. Females and juvenile males have a dull green crown, a grey throat with or without some red iridescence, a grey chest and belly, and a dark, rounded tail with white tips on the outer feathers.

The male has a striking reddish-pink crown and gorget, which are strongly iridescent and dependent on the angle of illumination and observation by female or male competitor birds. The iridescence results from large stacks of melanosomes in the feather barbules, occurring as layers separated by keratin. The barbules reflect incident light in the manner of partially-opened Venetian blinds, enabling the iridescence – which varies the head and gorget coloration with the changing angle of light – as a coloration advantage for courtship attraction and territory defense.

Male birds with elevated levels of protein in their diet have more colorful crowns and higher iridescence in their head feathers compared with male birds with low protein intake.

The male's call – scratchy and metallic – is typically used as the bird perches in trees and shrubs. Anna's hummingbirds have adapted to urban environments and are commonly seen in backyards and parks, and at feeders and flowering plants. Anna's hummingbirds eat flying insects.

Distribution

According to a 2021 estimate, there are 8 million Anna's hummingbirds in the western United States and Canada, with the population increasing since 1970. As of 2021, the International Union for Conservation of Nature Red List of Threatened Species lists Anna's hummingbird among species of least concern.Anna's hummingbirds are found along the western coast of North America, from southern Canada to northern Baja California, and inland to southern and central Arizona, extreme southern Nevada and southeastern Utah, and western Texas. They tend to be permanent residents within their range. However, birds have been spotted far outside their range in such places as southern Alaska, Saskatchewan, New York, Florida, Louisiana, and Newfoundland.

In response to rising temperatures at low elevations during climate change in the 21st century, Anna's hummingbirds have expanded their range into the cooler summer environments of higher-altitude ) mountainous terrains of California, such as the Sierra Nevada.

Habitat

Anna's hummingbirds are found along the western coast of North America, from southern Canada to northern Baja California, and inland to southern and central Arizona, extreme southern Nevada and southeastern Utah, and western Texas. They tend to be permanent residents within their range. However, birds have been spotted far outside their range in such places as southern Alaska, Saskatchewan, New York, Florida, Louisiana, and Newfoundland.

In response to rising temperatures at low elevations during climate change in the 21st century, Anna's hummingbirds have expanded their range into the cooler summer environments of higher-altitude ) mountainous terrains of California, such as the Sierra Nevada.

Reproduction

Open-wooded or shrubby areas and mountain meadows along the Pacific coast from British Columbia to Arizona make up "C. annas breeding habitat. The female raises the young without the assistance of the male. The female bird builds a nest in a shrub or tree, in vines, or attached to wires or other artificial substrates. The round, 3.8-to-5.1-centimetre diameter nest is constructed of plant fibers, downy feathers and animal hair; the exterior is camouflaged with chips of lichen, plant debris, and occasionally urban detritus such as paint chips and cigarette paper. The nest materials are bound together with spider silk. They are known to nest as early as mid-December and as late as June, depending on geographic location and climatic conditions.

Anna's hummingbirds may hybridize with other species, especially the congeneric Costa's hummingbird. These natural hybrids have been mistaken for new species. A bird, allegedly collected in Bolaños, Mexico, was described and named "Selasphorus floresii", or Floresi's hummingbird. Several more specimens were collected in California over a long period, and the species was considered extremely rare.

The specimens were the hybrid offspring of an Anna's hummingbird and an Allen's hummingbird. A single bird collected in Santa Barbara, California, was described and named "Trochilus violajugulum", or violet-throated hummingbird. It was later determined to be a hybrid between an Anna's hummingbird and a black-chinned hummingbird.