Breeding Range
Historically inhabited open canyons, foothills, escarpments, and river valleys that offered a vertical cliff face with a horizontal overhang for nest attachment. With the present use of artificial nesting structures such as bridges and buildings, the species is now found in a wide variety of habitats: grasslands, towns, broken forest, riparian edge. Avoids heavy forest, desert, and alpine areas. Most colony sites are located near open fields or pastures where the birds forage, and a water source is often nearby. Proximity to a mud source (for nest-building) is often cited as a breeding-habitat requirement (Emlen 1941, 1952), although some colonies are located several kilometers from the nearest mud supply (Coffey 1980, CRB, MBB). The species probably has more specific habitat requirements that are presently unknown, as Cliff Swallows are strangely absent from certain localities within their breeding range that would seem to offer appropriate nesting sites (Phillips et al. 1964, CRB, MBB).
Altitudinal range extends from the Lower Sonoran through the Transition zones, from sea level to about 2,770 m. Colonies occur rarely to 3,000 m; highest known to us is one of 50–100 nests at 3,200 m on Rendezvous Mtn., Teton Range, WY (CRB, MBB). There are no clear differences among subspecies in preferred breeding habitat.
Spring and Fall Migration
Often seen in savannahs and near bodies of water, but probably migrates through (over) a wide variety of habitats. Thousands of migrating birds assemble and roost in cornfields near playa lakes in s.-central Nebraska and in the Oklahoma and Texas panhandles during fall (C. D. Littlefield pers. comm., CRB). Commonly seen in coastal lowlands in Panama (Ridgley 1976). Probably migrates mostly at elevations below 1,000 m, but transients recorded to 3,800 m in South America (Meyer de Schauensee and Phelps 1978, Ridgley and Tudor 1989). Migrants concentrate over water surfaces and marshes when poor weather reduces abundance of flying insects (see Migration: migratory behavior).
Winter Range
Occurs in grasslands, agricultural areas, and in marshes. A roost of up to 50,000 birds was found in wetlands along the Rio Paraná in Argentina, about 50 km north of Buenos Aires (P. Burke pers. comm.). Another very large roost was in the Iberá Wetlands, Corrientes province, Argentina, about 700 km north of Buenos Aires (V. Bowers pers. comm.). Birds were sleeping in marsh vegetation, fanning out to forage over surrounding areas during the day, perhaps up to 20 km distant from the roost sites. Smaller roosts have been seen in marshes in Entre Rios province, Argentina (A. Jaramillo pers. comm.).
Historically inhabited open canyons, foothills, escarpments, and river valleys that offered a vertical cliff face with a horizontal overhang for nest attachment. With the present use of artificial nesting structures such as bridges and buildings, the species is now found in a wide variety of habitats: grasslands, towns, broken forest, riparian edge. Avoids heavy forest, desert, and alpine areas. Most colony sites are located near open fields or pastures where the birds forage, and a water source is often nearby. Proximity to a mud source (for nest-building) is often cited as a breeding-habitat requirement (Emlen 1941, 1952), although some colonies are located several kilometers from the nearest mud supply (Coffey 1980, CRB, MBB). The species probably has more specific habitat requirements that are presently unknown, as Cliff Swallows are strangely absent from certain localities within their breeding range that would seem to offer appropriate nesting sites (Phillips et al. 1964, CRB, MBB).
Altitudinal range extends from the Lower Sonoran through the Transition zones, from sea level to about 2,770 m. Colonies occur rarely to 3,000 m; highest known to us is one of 50–100 nests at 3,200 m on Rendezvous Mtn., Teton Range, WY (CRB, MBB). There are no clear differences among subspecies in preferred breeding habitat.
Spring and Fall Migration
Often seen in savannahs and near bodies of water, but probably migrates through (over) a wide variety of habitats. Thousands of migrating birds assemble and roost in cornfields near playa lakes in s.-central Nebraska and in the Oklahoma and Texas panhandles during fall (C. D. Littlefield pers. comm., CRB). Commonly seen in coastal lowlands in Panama (Ridgley 1976). Probably migrates mostly at elevations below 1,000 m, but transients recorded to 3,800 m in South America (Meyer de Schauensee and Phelps 1978, Ridgley and Tudor 1989). Migrants concentrate over water surfaces and marshes when poor weather reduces abundance of flying insects (see Migration: migratory behavior).
Winter Range
Occurs in grasslands, agricultural areas, and in marshes. A roost of up to 50,000 birds was found in wetlands along the Rio Paraná in Argentina, about 50 km north of Buenos Aires (P. Burke pers. comm.). Another very large roost was in the Iberá Wetlands, Corrientes province, Argentina, about 700 km north of Buenos Aires (V. Bowers pers. comm.). Birds were sleeping in marsh vegetation, fanning out to forage over surrounding areas during the day, perhaps up to 20 km distant from the roost sites. Smaller roosts have been seen in marshes in Entre Rios province, Argentina (A. Jaramillo pers. comm.).