White-throated Swift

The white-throated swift (Aeronautes saxatalis) is a swift of the family Apodidae native to western North America, south to cordilleran western Honduras. Its coastal range extends as far north as Northern California, while inland it has migratory populations found throughout the Great Basin and Rocky Mountain regions, ranging as far north as southern British Columbia. White-throated swifts are found in open areas near cliffs, rock faces, or man-made structures, where they roost. Swifts are social birds, and groups are often seen roosting and foraging for flying insects together. Description The white-throated swift is medium-sized bird that is primarily black and white. Its back and wings are blackish-brown or black, and its breast, belly, chin, and throat are white. In newly molted adults, the dark feathers may have a slight greenish sheen, though this is rarely observable in the field. Sexes cannot be distinguished by plumage. Juvenile (first basic) plumage is similar to adult (definitive basic) plumage, but with the feathers on juveniles' heads and necks appearing duller and paler. Adults are generally 15–18 centimeters in length, and have a tail with a relatively shallow 10 millimeter-deep notch. Adult swifts weigh between 28 and 36 grams, with a mean weight recorded as 32.5 grams, and there is no difference in size between males and females. The white-throated swift has a wingspan of 35.5 cm. White-throated swifts can appear similar to American black swifts and Vaux's swifts, which also occur in western North America, but they can be distinguished by their white underparts which both other species lack. Taxonomy The order in which white-throated swifts are placed is debated, with some taxonomies placing them in Caprimulgiformes, but others putting them in Apodiformes. The difficulty in taxonomic placement is largely due to the morphological similarities between swifts which make determining the history of evolutionary divergence difficult. At lower taxonomic levels, White-throated swifts belong to the family Apodidae and the genus Aeronautes.Aeronautes includes only two other species, the Andean swift (Aeronautes andecolus) and the white-tipped swift (Aeronautes montivagus). There are two subspecies: A. s. saxatalis, and A. s. nigrior. The A. s. saxatalis subspecies comprises birds that winter in North America south to the Isthmus of Tehantepec in Oaxaca, Mexico, while birds of the A. s.