The cave swallow (Petrochelidon fulva) is a medium-sized, squarish-tailed swallow belonging to the same genus as the more familiar and widespread cliff swallow of North America. The cave swallow, also native to the Americas, nests and roosts primarily in caves and sinkholes. Cave swallows are found in Mexico and the Greater Antilles, with fall and winter vagrants reaching the east and Gulf Coasts of the U.S. Breeding colonies occur in south-eastern New Mexico, Texas, Florida, the Greater Antilles, portions of southern Mexico, and along the west coast of South America. Five subspecies are currently recognized according to Birds of North America, three occurring in North America and two in South America. Description The cave swallow measures 12 to 14 cm in length and weighs 19 g on average. The largest of the five subspecies, P. f. pallida, has an average wing length between 107.0 and 112.3 mm; the smallest subspecies, P. f. aequatorialis, has an average wing length between 93.0 and 93.5 mm. Differences between the sexes are minimal, both are similar in size and weight and are difficult to distinguish from their plumage. It has grey-blue upperparts and brown-tangerine forefront and throat. Taxonomy The cave swallow is a passerine belonging to the swallow and martin family, Hirundinidae. The genus Petrochelidon is a collection of cliff-nesting swallows and martins, though only the two South American subspecies prefer nesting on cliff-faces. The three North American subspecies prefer nesting in caves and sinkholes, as their common name suggests. Five subspecies of Petrochelidon fulva are currently recognized. The three North American subspecies are P. f. fulva, P. f. pallida, and P. f. citata. All three will usually nest in natural caves and sinkholes, or in some areas they will nest in or underneath man-made structures (highway culverts, under bridges, etc.). All three have larger wing-spans than the remaining two South American subspecies. P. f. fulva occurs in the Greater Antilles and southern Florida. P. f. pallida (also known as P. f. pelodoma) is found farther west in the south-western United States and into north-eastern Mexico. P. f. citata has the southernmost range of the North American subspecies and is found on the Yucatán Peninsula of Mexico. The remaining two South American subspecies of the cave swallow are sometimes regarded as distinct species separate from the species fulva; not only is their range geographically separate from the North American subspecies but they also choose