Conservation Status

There is one Critically Endangered, facing an extremely high risk of extinction, species of swallow, the white-eyed rivermartin. There are estimated to be fewer than fifty adults of the species, and the bird, which is native to Thailand, has not been

APARTMENT DWELLERS

North American purple martins that live east of the Rocky Mountains rely exclusively on human-made "apartment-style" martin houses for nesting. The practice began hundreds of years ago when Native Americans hung hollow gourds for the birds to nest in. Western purple martins are not colonial and typically nest in tree cavities, although some will use solitary nesting boxes if available.

sighted in twenty years and therefore may already be extinct. Their decline has been caused by hunting, habitat destruction, and deforestation.

Four species classified as Vulnerable, facing a high risk of extinction, are also noted by the World Conservation Union (IUCN): the blue swallow, white-tailed swallow, Bahama swallow, and golden swallow. Habitat loss due to deforestation and agricultural land use has been particularly destructive to cavity nesting and grassland-dwelling swallows.

BARN SWALLOW

Hirundo rustica

SPECIES ACCOUNTS

Physical characteristics: The barn swallow has iridescent dark blue plumage on its back, with a dark orange throat and orange to buff breast, although there are some coloring variations among the six subspecies of the bird. It is the only species of swallow that has a long, deeply forked tail. The average size of the barn swallow is 7.5 in (19 cm) long with a weight of .6 oz (17 g).

Geographic range: During the summer months, barn swallows can be found throughout North America. The birds have the most widespread range of any swallow species, and are also found throughout Europe, Asia, Myanmar, Israel, and northern Africa. North American barn swallows winter in Central and South America, while their European and Asian counterparts migrate to central and southern Africa and south and Southeast Asia.

Habitat: During breeding season, barn swallows settle in habitats with abundant insects and some access to wet earth (such as from riverbanks or drainage ditches). They build their cone-shaped, open-topped mud nests in sheltered natural areas, including cliff overhangs and caves. They also quite frequently choose human-made structures to house their families, creating nests in the rafters of barns, the underside of highway overpasses, and the eaves of other buildings.

Barn swallow nests hold three to six eggs, and both female and male may share incubation and feeding duties. (Dwight Kuhn/ Bruce Coleman Inc. Reproduced by permission.)

Because of their abundant insect population, farms make ideal places for barn swallows to live, and the birds can frequently be seen flying close to crops feeding on insects. Along with feathers, the straw and mud that are found in livestock areas also make excellent building materials for a barn-based nest. Barn swallows migrate towards warmer climates in the winter, and can be found in drier climates, such as the desert, when nesting isn't a priority.

Diet: Barn swallows feed on flying insects.

Behavior and reproduction: Barn swallows return to the same area each year to breed, hatch, and fledge, raise until they can fly, their young. Often, they will use the same nest year after year if it remains intact. Building a mud nest may take anywhere from a week to a month, and both male and female work together, using thousands of mud pellets carried one by one in their bills. Straw and grass are also used, and the nests are lined with feathers. Barn swallow nests hold three to six eggs, and both female and male may share incubation duties, sitting on the eggs to keep warm. The birds are colonial, meaning that they often build nests in groups; however, males will defend their nest vigorously from both predators, animals that hunt them for food, and other barn swallows.

Barn swallow nests hold three to six eggs, and both female and male may share incubation and feeding duties. (Dwight Kuhn/ Bruce Coleman Inc. Reproduced by permission.)

Barn swallows and people: Because of their appetite for flying insects that annoy, destroy vegetation, and can carry disease, barn swallows are popular neighbors, particularly to farmers.

Conservation status: Barn swallows are abundant, and not considered threatened. ■

American cliff swallow (Hirundo pyrrhonota)

Resident Breeding

American cliff swallows build their mud nests not only on the underside of cliffs, but also on the outside of overhanging human-made structures, such as bridges and dams. (© Brenda Tharp/Photo Researchers, Inc. Reproduced by permission.)

AMERICAN CLIFF SWALLOW

Hirundo pyrrhonota

American cliff swallows build their mud nests not only on the underside of cliffs, but also on the outside of overhanging human-made structures, such as bridges and dams. (© Brenda Tharp/Photo Researchers, Inc. Reproduced by permission.)

Physical characteristics: American cliff swallows have a long square tail, black to blue back, rust-colored throat and rump, white forehead spot, and white to buff underside. They average 5.1 in (13 cm) in length and 0.8 oz (22.7 g) in weight.

Geographic range: This species breeds throughout North America and migrates to Central and South America in the winter.

Habitat: The cliff swallow builds its mud nest in covered areas such as the underside of cliffs and on the outside of overhanging humanmade structures. They are found in a wide variety of biomes where water is available, and even in desert areas near towns and humanmade construction. The nests are typically built in colonies, and unlike the barn swallow nest, they are completely enclosed with a small hole for coming and going.

Diet: American cliff swallows feed on insects while the birds are flying.

Behavior and reproduction: Cliff swallows are monogamous, migrating birds. They return to their mud nests annually to lay a clutch of three to six eggs, which they incubate for about two weeks. The brood leaves the nest approximately three weeks after hatching. Some cliff swallows are parasitic, and will lay their eggs in other cliff swallow nests within their colony to be incubated and raised by the other birds.

American cliff swallows and people: Human-made structures like bridges and dams provide an attractive spot for many cliff swallow colonies and in this sense the birds have benefited from development and construction.

Conservation status: American cliff swallows are common and are not considered threatened. ■

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