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| Allen's hummingbird | |
|---|---|
| Name | Allen's hummingbird |
| Genus | Selasphorus |
| Species | sasin |
| Authority | (Lesson, 1829) |
Allen's hummingbird
Allen's hummingbird is a small North American bird in the family Trochilidae found primarily along the western coast of the United States and parts of Mexico. It is notable for its sexual dimorphism, migratory behavior, and close ecological associations with coastal California landscapes and urban gardens in metropolitan areas such as Los Angeles and San Francisco. Ornithologists, naturalists, and conservation organizations have studied its population trends in the context of land-use change and climate variability.
First described by René Lesson in 1829, Allen's hummingbird is placed in the genus Selasphorus within the family Trochilidae. Historical classification involved comparisons with the rufous hummingbird and other North American selasphorine species, prompting work by taxonomists at institutions such as the American Ornithological Society and researchers publishing in journals like The Auk and Condor. Molecular phylogenetic studies using mitochondrial and nuclear markers by teams affiliated with University of California, Berkeley, Smithsonian Institution, and Yale University clarified relationships among bee hummingbirds and clarified subspecific limits, including differentiation from related forms found in Baja California and the Pacific Coast. Nomenclatural decisions have followed guidelines from the International Commission on Zoological Nomenclature and have been incorporated into checklists maintained by the International Ornithologists' Union.
Adults are sexually dimorphic: males typically have an iridescent orange-red gorget and coppery back, while females show more muted green and rufous tones. Field guides from the Cornell Lab of Ornithology, National Audubon Society, and British Trust for Ornithology describe size around 7–10 cm, a wingspan adapted for rapid wingbeats, and a specialized bill for nectar feeding. Plumage comparisons reference species such as the rufous hummingbird, calliope hummingbird, and broad-tailed hummingbird for distinguishing features like tail shape, gorget color, and flight pattern. Morphological studies in museums at Smithsonian National Museum of Natural History and California Academy of Sciences document seasonal molt, juvenile plumages, and clinal variation along the Pacific Coast.
The species breeds primarily along the coastal and near-coastal regions of California from the southern San Francisco Bay Area south through Baja California for certain populations, with migratory movements that connect breeding sites to wintering grounds in southern California and northwestern Mexico. Habitats include coastal scrub, oak woodland, riparian corridors, chaparral, and human-altered environments such as suburban gardens, parks, and coastal reserves like Point Reyes National Seashore and Channel Islands National Park. Range dynamics have been documented by surveys conducted by organizations like the North American Breeding Bird Survey, eBird, and regional chapters of the Audubon Society, indicating both localized stability and shifts related to urbanization and climatic factors tracked by agencies such as the California Department of Fish and Wildlife.
Allen's hummingbirds exhibit territorial foraging behavior, defending nectar sources from conspecifics and other hummingbird species at flowers of native and nonnative plants. Studies conducted by researchers at University of California, Santa Cruz and monitoring programs at Stanford University have observed interactions with plant communities including native salvia, manzanita, and ornamental species in botanical gardens like the Huntington Library, Art Museum, and Botanical Gardens. They engage in aerial displays during courtship, employ traplining and territorial strategies described in behavioral ecology literature from Princeton University and Duke University, and participate in mutualistic pollination networks documented by ecologists at University of California, Davis. Predation pressures involve raptors such as sharp-shinned hawk in urban canyons and introduced predators noted by California Academy of Sciences studies. Energetic ecology research references metabolic rates measured in lab studies at Oregon State University and field observations by citizen scientists tied to The Nature Conservancy projects.
Breeding season typically occurs from late winter into summer along the coast, with nest construction using plant down, spider silk, and lichens in shrubs or trees; nests and clutch parameters have been described in accounts held by Museum of Vertebrate Zoology at UC Berkeley. Females alone build the nest, incubate usually two eggs, and provide all parental care, a pattern noted in classic avian life-history work by researchers at Cornell Lab of Ornithology and University of Washington. Nest success, fledging rates, and timing have been quantified in long-term studies by regional conservation groups and university collaborations, which also examine impacts of weather events such as El Niño on reproductive output. Juvenile dispersal and first-year survival are monitored via banding programs operated by the United States Geological Survey and independent ringing schemes in Mexico.
Conservation assessments by entities including the IUCN and state agencies consider habitat loss from coastal development, pesticide exposure linked to agricultural practices in the Central Valley, competition and hybridization with expanding populations of related hummingbirds, and climate-driven changes to flowering phenology. Conservation actions promoted by NGOs like Sierra Club, The Nature Conservancy, and local chapters of the Audubon Society emphasize habitat protection in regional reserves, planting native nectar sources in urban landscapes, and reducing pesticide use. Monitoring through the North American Breeding Bird Survey and community science platforms such as eBird remains central to tracking population trends and informing land-management policies pursued by entities like the California Coastal Commission and municipal parks departments.