Swallows and Martins
Swallows and Martins
Biology of swallows and martins
North american swallows and martins
Swallows and martins are small, fast-flying, agile birds in the family Hirundinidae. There are about 88 species in this family worldwide, mostly found in open habitats, where they forage aerially for their prey of flying insects.
There is no particular biological difference between swallows and martins. Sometimes these names are used interchangeably, as in the case of Riparia riparia, known as the sand martin in Western Europe, and as the bank swallow in North America.
Biology of swallows and martins
Swallows and martins have relatively long, pointed wings, and they are swift and agile fliers. The feet of these birds tend to be small and weak, and are used for little more than perching. These birds often rest on wires and exposed branches of trees. During migration, large numbers of swallows and martins may roost together on these sorts of perches, often in mixed-species flocks. Swallows may also forage in large, mixed-species flocks during migration.
Many species of swallows and martins are rather plainly marked with dark brown or black backs and wings and a white breast. Other species are more boldly patterned, and may be brightly colored with red, yellow, and iridescent green and purple. Most species have a notched tail, and some have a deeply forked tail.
Swallows have a short but broad mouth, which can open with a very wide gape, an adaptation for catching insects on the wing. This food of flying insects is sometimes referred to as aeroplankton.
Many species of swallows and martins nest in colonies of various sizes, and most species are gregarious during the non-breeding season. Some swallows nest in natural or artificial cavities. Other species nest in tunnels that they dig in earthen banks. Many species
construct an urn-like cavity of hardened mud or clay, or they make cup-shaped nests of these materials. The natural substrate for attachment of the constructed nests is cliffs and other sheer surfaces. However, some species use bridges and buildings as substrata upon which to build their clay nests.
All species of swallows and martins migrate between their breeding and non-breeding habitats. Species that breed at high latitudes can migrate great distances, for example, about 6,831 mi (11,000 km) in the case of the European swallow (Hirundo rustica), some of which breed in northern Europe and winter in South Africa.
North american swallows and martins
The most familiar swallow in North America is the barn swallow (Hirundo rustica). This is a cosmopolitan species that also occurs under other common names in Eurasia, Africa, Southeast Asia, and Australia. The barn swallow is an attractive bird, with a deeply forked tail, an iridescent purple back, and a brick-red breast. Barn swallows often nest in small colonies. The natural nesting habitat is cliffs and caves, where these birds build their cup-nests of mud bonded with grass. Barn swallows also commonly build their nests on the sides of buildings and bridges. The barn swallow breeds south of the tundra over most of North America and Mexico, and winters in South America.
The cliff swallow (Petrochelidon pyrrhonota) looks rather similar to the barn swallow, but it does not have a forked tail, and it has a white patch on its forehead, a buff rump, and a white breast. The cliff swallow is a colonial nester, building its roofed, mud nests on cliffs, and also on structures made by humans, such as bridges, dams, and buildings. The cliff swallow breeds locally over a wide range, from the subarctic tundra to southern Mexico, and winters in South America.
The bank swallow (Riparia riparia) also breeds over much of North America south of the tundra, as well as in Eurasia. North American populations of bank swallows winter in South America. The bank swallow is a brown-backed species, with a brown band across the chest. The bank swallow nests in colonies, typically excavating tunnels for its nests in the earthen banks of rivers. This species also uses the sides of gravel pits as a place to nest.
The rough-winged swallow (Stelgidopteryx ruficollis) is similarly marked to the bank swallow, but it lacks the brown breast-band, and has a darker breast. This is a non-colonial nester, which digs burrows in riverbanks, or sometimes nests in holes in cement bridges and other built structures. This species breeds widely south of the boreal forest of North America and into northern South America. The rough-winged swallow winters from the southern United States to South America.
The tree swallow (Tachycineta bicolor) has an iridescent, dark-blue or green back, and a white breast. This species breeds south of the low-arctic tundra to the northern states, and winters from the southern United States to Central America. The tree swallow nests in natural cavities in trees, or in cavities previously excavated and used by woodpeckers. This species will also take readily to nest boxes.
The violet-green swallow (Tachycineta thalassina) has a superficial resemblance to the tree swallow, with an iridescent violet-green back. This species breeds in the western United States, and winters in northern Central America and Mexico. The violet-green swallow generally nests in cavities in trees or in crevices of cliffs.
The purple martin (Progne subis) is the largest swallow in North America. Male purple martins are a uniformly iridescent purple, while females are brown. The natural nesting sites of this colonial species are hollow cavities in trees, but purple martins also utilize multi-celled nesting boxes provided by humans. This species breeds in an area from southern Canada to Mexico, and winters in South America.
Interactions with humans
Swallows are boisterous and active birds, which maintain a stream of cheerful twitterings that many people find pleasing. The fact that some species nest in the vicinity of human habitations means that people can easily watch the comings and goings of these small, charismatic birds. Observers can gain an impression of the daily life of the swallow, from the building of nests, through the rearing of nestlings, to the trials and tribulations by which fledglings learn to fly and to hunt their own food of insects.
Swallows of all species eat enormous numbers of flying insects. Some of the prey insects (such as mosquitos and blackflies) are regarded as pests by humans. As a result, swallows nesting near homes are often considered to be beneficial. Barn and cliff swallows construct their mud nests on buildings. These species do not need encouragement, only tolerance of the small annoyances that some people might perceive about the defecations of these birds. The nesting of tree swallows can be assisted by providing simple nest boxes, while purple martins can be attracted by providing multiple-unit apartment boxes. Because of the relatively large number of birds that can be supported, a colony of purple martins can have a significant effect on the abundance of biting flies in its vicinity.
See also Insectivore.
Resources
BOOKS
Brown, C., and M. Brown. Coloniality in the Cliff Swallow. Chicago: University of Chicago Press, 1996.
del Hoyo, J., A. Elliott, and J. Sargatal. Handbook of the Birds of the World. Vol. 9,Cotingas to Pipits and Wagtails. Barcelona: Lynx Edicions, 2004.
Forshaw, Joseph. Encyclopedia of Birds. 2nd ed. New York: Academic Press, 1998.
Turner, A. The Swallow. London: Hamlyn, 1994.
Turner, A., and C. Rose. Swallows and Martins: An Identification Guide and Handbook. Boston: Houghton Mifflin, 1989.
Bill Freedman