Cliff Swallow

识别特征

The cliff swallow's average body length is 13 cm (5.1 in), and they have short legs and small bills with relatively long pointed wings. Adult cliff swallows have an overall dark brownish plumage covering both their back and wings, and they have a characteristic white forehead, rich red-coloured cheeks with a dark throat, basic white underparts and a buffy-coloured rump. In good lighting conditions, their crowns and mantle feathers are iridescent. The Northern population is slightly larger in body size and also differs in facial markings from the Mexican population of cliff swallows, which have a chocolate-brown patch on their foreheads.<p>The male and female have identical plumage, therefore sexing them must be done through palpation of the cloaca. During the breeding season, the males will have a harder cloaca that is more pronounced because the seminal vesicles are swollen. In addition, during incubation females will lose feathers on their lower breast to create a warm patch for sitting on their eggs. Cliff swallows are similar in body plumage colouring to the related barn swallow species but lack the characteristic fork-shaped tail of the barn swallow prominent during flight. The cliff swallows have a square-shaped tail.<p>Juvenile cliff swallows have an overall similar body plumage colouring to the adults, with paler tones. The juveniles lack the iridescent adult plumages, and their foreheads and throats appear speckled white. The juvenile cliff swallows' white forehead and throat markings have high variance between unrelated individuals compared with those from the same clutch. These distinctive white facial markings disappear during maturity following their complex-basic moult pattern, because their pre-formative plumage is different from the basic plumage. The pre-formative facial plumage has been suggested as a possible way for parents nesting in large colonies to recognize their chicks.

分类信息

The cliff swallow belongs to the largest order and dominant avian group – Passeriformes. They are the perching birds, or the passerines. All the bird species in this order have four toes, three pointing forward and one pointing backwards (anisodactylous), that enable them to perch with ease. The sub-order that the cliff swallow belongs to is Oscines (or Passeri), for the songbirds. The family that encompasses approximately 90 species of swallows and martins, Hirundinidae, includes birds that have small stream-lined bodies made for great agility and rapid flight. Furthermore, those in the family Hirundinidae have short-flat bills for their largely insectivorous diets, small feet because they spend much of their time in flight and long wings for energy-efficient flight.<p>There are five subspecies of cliff swallow distinguished on the basis of plumage colour, body size, and distribution – Petrochelidon pyrrhonota pyrrhonota, P. p. melanogaster, P. p. tachina, P. p. hypopolia, P. p. ganieri. In addition, three core genera of hirundo were established on the basis of molecular studies: Hirundo sensu stricto, containing the barn swallow; Cecropis, containing the red-rumped swallow; and Petrochelidon, containing the cliff swallow. The genetic tests deemed Petrochelidon and Cecropis sister to each other and both closest to Delichon, the house martins. Finally, the cave swallow was identified as the nearest living relative in North America of the cliff swallow. The cave swallow has a similar plumage to the cliff swallow; however, the former has a dark cap and pale throat, and also a much smaller distribution in North America, most likely due to a decline in suitable cave sites.

学名

Petrochelidon pyrrhonota

命名信息

(Vieillot, 1817)

目

Passeriformes

科

Hirundinidae

属

Petrochelidon

分布与栖息地

As their name suggests, throughout history the cliff swallows concentrated their nesting colonies along mountain cliffs, primarily by the western North American coast. Today, with the development of highways, concrete bridges, and buildings this adaptable bird species is rapidly adjusting its common nesting sites, with populations expanding further east and building their mud nests on these concrete infrastructures. Thus, the cliff swallow's breeding range includes large areas across Canada and the United States, excluding some Southern and Northern areas. The majority of nesting colonies are situated in close proximity to fields, ponds, and other ecosystems that would hold a large variety of flying insect populations to sustain their energy requirements during the breeding season.<p>The cliff swallows' wintering grounds have been recorded as South American countries, such as Southern Brazil, Uruguay, and parts of Argentina. However, their behavior and populations have yet to be extensively studied on their wintering grounds leaving room for new information about this species. The cliff swallows are long-distance day-migrants that generally travel along the North American coastlines. The Eastern populations travel through Florida, and the Western populations through Mexico and Central America down to their destinations. Flocks containing large numbers of cliff swallows have been recorded migrating together, but whether they stay together or disperse to different locations is unknown.

繁殖区

NA, MA : widespread

非繁殖区

to s SA

迁徙

Complete migrants

行为

Migration pattern: Complete migrants.

保护状况

Population trend: rising.

种群趋势

rising