Saturday, 2 February 2013

American Cliff Swallow


order : Passeriformes      Genus & Species : Hirundinidae     Family : Hirundo pyrrhonota

The extremely social American cliff swallow’s life revolves around its flock: it forages, preens, gathers mud, sunbathes, nests, migrates and winters in large groups. The American cliff swallow is an accomplished aerialist; if it’s not gathering mud for its nest, the bird is usually in the air. They found in North America, from Alaska south throughout most of the U.S. to central Mexico; winters in South America from Brazil to Argentina. 

Habitat : The cliff swallow migrates to its North American breeding grounds, arriving from March to May.True to its name, the bird has historically nested on the sides of steep cliffs. Though the cliff swallow still settles along the cliffs and canyons of western North America, it has adapted to alternative nesting sites across the U.S.: many bridges, dams or buildings offer protective overhangs and suitable vertical surfaces on which to attach a nest. Swallows also need open areas for foraging and a water source for the mud necessary to build their nests. In the fall, the birds and their young are among the earliest migrants south; large flocks fly to South America. 

Food & Feeding : The American cliff swallow feeds entirely on insects caught in flight. The bird chases after flying ants, wasps, grasshoppers, dragonflies, mosquitoes and beetles, including the destructive cotton-boll weevils; the swallow’s menu includes 84 insect families from 10 orders. The bird holds its tiny, gaping mouth as wide as it can to scoop up hundreds of insects as it darts along. Foraging in large groups of up to 2,000 birds, the cliff swallow searches for swarms of insects.The birds tend to focus on areas of relatively high altitudes; however, in cool and cloudy weather the cliff swallows feed just above the ground or water surface due to lack of visibility and decreased availability of swarming insects. In this damp and dreary climate, the bird tends to forage alone. Groups always tend to follow each other; if one is feeding on a big swarm, another will follow to scout out the area. This holds true for solitary feeding birds as well. American cliff swallows never have a problem sharing their food sources. 
Behavior : American cliff swallows are very social. Large flocks forage together in flight throughout the day; birds have been timed at up to almost 30 mph. In cool and cloudy weather, the swallow gives a “squeak” call to announce the discovery of an insect swarm.This call attracts other birds to the food source. The birds preen their feathers and sunbathe together at their daytime perches on wires, small twigs and rooftops, and they roost together at night, clinging to reeds and tall grasses. To protect their young against enemies, such as American kestrels, black-billed magpies, bull snakes and rats, the cliff swallows build sheltered nests in large colonies. Central nests are sought after, because the nests at the edges of a colony are more vulnerable to attack. But there is not always safety in numbers: very large, conspicuous colonies attract predators. Cliff swallows usually give alarm calls and surround the predator in a loose group to drive it off. 
Breeding : Cliff swallows arrive at their breeding areas by May.The birds are more comfortable in flight; on land, they shuffle along when gathering mud to build their mud nests. They often reuse nests left from the previous summer and need to add mud only to the nest’s entrance, a narrow tunnel that usually points downward. The cliff swallow generally nests in dense colonies on cliffs, banks, dams and bridges; groups of several thousand nests have been observed. Swallows often fight for safer, centrally located nests in these colonies. The female swallow incubates the 4–5 eggs for up to 16 days; after hatching, the chicks are able to fly by 24 days, but still rely on their parents for food.The juveniles gather to form large crèches and depart with their parents for wintering grounds from July to September. 

Bill : The swallow opens its short, triangularshaped bill wide to capture insects in flight. 
Plumage : The adult cliff swallow’s dark, brown-red throat patch, pale-buff rump and triangular white forehead patch distinguish it in the field.The crown, back and wings are a glossy blue-black.The sexes look similar. 
Feet : The swallow’s small feet aren’t used very often, since the bird spends most of its time in the air. Its tiny toes cling best to thin wire and small twigs. 
In Flight : When the cliff swallow glides, its long, pointed wings and nearly squared tail make it easily identifiable. 

Weight : 0.7–1.0 oz. 
Length : 5.5" 
Wingspan : 12-12.25"
Sexual Maturity : 1 year
Breeding Season : April–August 

Cliff swallows choose mud with high clay and silt content; this makes the nest less likely to crumble when dry, important when walls are shared.