Anna's Hummingbird - Reproduction

Reproduction

Open-wooded or shrubby areas and mountain meadows along the Pacific coast from British Columbia to Arizona make up C. anna's breeding habitat. The female raises the young without the assistance of the male. The female bird builds a large nest in a shrub or tree, or in vines or on wires. The round, 3.8-to-5.1-centimetre (1.5 to 2.0 in) diameter nest is built of very small twigs, lichen and other mosses, and often lined with downy feathers or animal hair. The nest materials are bound together with spider silk or other sticky materials. They are known to nest early as mid-December and as late as June.

Unlike most hummingbirds, the male Anna's Hummingbird sings during courtship. The song is thin and squeaky. During the breeding season, males can be observed performing a remarkable display, called a display dive, on their territories. The males also use the dive display to drive away rivals or intruders of other species. When a female flies onto a male's territory, he rises up approximately 30 metres (98 ft) before diving over the recipient. As he approaches the bottom of the dive the males reach an average speed of 27 m/s, which is 385 body lengths per second. At the bottom of the dive the male travels 23 metres per second (51 mph), and produces a loud sound described by some as an "explosive squeak" with his outer tail-feathers.

Anna's Hummingbirds will sometimes hybridize with other species, but this is not very common. These natural hybrids have been mistaken for new species. A bird, allegedly collected in Bolaños, Mexico, was described and named Selasphorus floresii (Gould, 1861), or Floresi's Hummingbird. Several more specimens were collected in California over a long period, and the species was considered extremely rare. It was later determined that 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 (Jeffries, 1888), or Violet-throated Hummingbird. It was later determined to be a hybrid between an Anna's Hummingbird and a Black-chinned Hummingbird.