Anna's hummingbird

Anna's hummingbird
Robert McMorran, United States Fish and Wildlife Service · Public domain · source
Name	Anna's hummingbird
Status	LC
Status system	IUCN3.1
Genus	Calypte
Species	anna
Authority	(Lesson, 1829)

Anna's hummingbird

Anna's hummingbird is a small North American bird species in the Trochilidae family, notable for its iridescent plumage and year-round presence in urban and suburban landscapes. Its expansion in range and adaptation to human-modified environments have made it a subject of interest for ornithologists, conservationists, and amateur naturalists across California, Oregon, and into British Columbia.

Taxonomy and evolution

Originally described by René Lesson in 1829, the species is placed in the genus Calypte, alongside related taxa studied in molecular analyses by researchers affiliated with institutions such as the Smithsonian Institution and the American Museum of Natural History. Phylogenetic work using mitochondrial and nuclear markers has clarified relationships among New World Trochilidae lineages, linking Calypte to clades examined in publications from University of California, Berkeley and Harvard University. Paleontological evidence for hummingbird diversification is sparse, but biogeographic synthesis drawing on data from the Pleistocene and studies by teams at the Natural History Museum, London informs hypotheses about Neotropical origins and northward dispersal patterns into western North America.

Description and identification

Adults exhibit sexual dimorphism described in field guides produced by the National Audubon Society and the Cornell Lab of Ornithology. Males feature a rose-pink to magenta gorget and crown, noted in plates used by the British Ornithologists' Union and by illustrators working for the Royal Ontario Museum, while females and immatures show more subdued green and gray tones referenced in keys from the American Ornithologists' Union. Measurements reported in avian handbooks from the University of Washington indicate a body length of approximately 9–10 cm and a wingspan near 12 cm. Identification in the field often relies on plumage diagnostics, vocalizations cataloged at the Macaulay Library, and distinctive flight displays documented by videographers working with the BBC Natural History Unit.

Distribution and habitat

Historically centered on the coastal regions of California and parts of Baja California, the species' documented range has expanded inland and northward, with breeding records in Nevada, Arizona, Washington (state), and British Columbia. Range shifts have been charted by organizations such as the Audubon Society and provincial agencies in Canada using citizen-science platforms like eBird managed by the Cornell Lab of Ornithology. Habitats include scrub, chaparral, riparian corridors, parks, and residential gardens—landscapes often surveyed by biologists from the U.S. Geological Survey and municipal natural resource departments in cities like San Francisco and Los Angeles.

Behavior and ecology

Territoriality, courtship displays, and migratory tendencies have been the focus of studies published through the Cooper Ornithological Society and researchers at the University of California, Los Angeles. Males perform hovering displays and high-speed dive displays described in field reports archived by the American Birding Association and documented on nature programs produced by National Geographic Society. Daily activity patterns, thermoregulation (including torpor), and interactions with competitors such as rufous hummingbird and Allen's hummingbird have been investigated in collaboration with labs at the University of British Columbia and the University of California, Davis.

Feeding and diet

Nectar is the primary energy source, with floral associations recorded in botanical surveys conducted by the California Native Plant Society and urban ecology studies by the U.S. Forest Service. Common nectar plants frequented include species cultivated in gardens and recorded by horticulturalists at the Missouri Botanical Garden and the Royal Botanic Gardens, Kew. Insectivory—capturing small arthropods on the wing or gleaned from foliage—has been documented in entomological studies associated with the Entomological Society of America and is important for protein during breeding, as noted by researchers at the University of Arizona.

Reproduction and lifecycle

Breeding phenology, nest construction with plant down and spider silk, and clutch characteristics have been described in monographs by the American Ornithological Union and fieldwork reports by biologists at the California Department of Fish and Wildlife. Females build cup nests on horizontal branches or man-made structures, lay typically two eggs, and alone incubate and rear young—a reproductive strategy outlined in conservation assessments by the Nature Conservancy and life-history reviews in journals linked to the Ecological Society of America. Juvenile development, fledging intervals, and survival rates have been monitored through banding programs coordinated with the U.S. Fish and Wildlife Service.

Conservation and human interactions

Classified as Least Concern on criteria developed by the IUCN Red List, the species benefits from supplemental resources such as sugar-water feeders promoted by community groups including the Audubon Society of California and backyard habitat initiatives by the National Wildlife Federation. Urban expansion, climate variability, and introduced plantings have influenced its distribution, prompting studies by climate researchers at Stanford University and municipal planning offices. Human-wildlife interactions include conservation outreach run by organizations like the Xerces Society and species accounts in field guides produced by publishers such as Princeton University Press. Potential threats include window collisions and pesticide exposure addressed in mitigation guidelines from the U.S. Environmental Protection Agency.

Category:Trochilidae Category:Birds of North America