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Photo by Bruce Bonebrake
Photo Copyright Bruce Bonebrake
Purple Martin
Progne subis
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S2S3B
External links
General information
The purple martin, Progne subis, breeds throughout eastern North America, as well as on the Pacific coast and in parts of interior western North America and Mexico. It winters in South America. The purple martin is rare during summer in the mountains of northern and central Utah, but is more common during migration in the lowland valleys, where it formerly bred. The original habitat of this species was probably forest edge and riparian habitats, but many populations now inhabit cities and towns almost exclusively. The current breeding habitat of this species in Utah, however, is a natural habitat: aspen and coniferous forests near mountain lakes. The diet of this species is flying insects.
Natural nest sites of this species are cavities, such as old woodpecker holes in trees and holes in cliffs, but this species now extensively utilizes artificial sites, such as nest boxes and bird houses. Nest cavities are often in open areas near water and are usually more than five feet above the ground. The five to eight eggs (usually four or five) are incubated by the female parent for fifteen to eighteen days. The young are tended by both parents and leave the nest after twenty-six to thirty days. Nesting is typically in colonies, and males are often polygynous.
Species range
BREEDING: west of Cascades and Sierra Nevada from southwestern British Columbia south to northwestern Mexico and Arizona; east of Rocky Mountains from northeastern British Columbia, central Alberta, east through northern Minnesota, northern Wisconsin, southern Ontario, to Nova Scotia, south to Gulf coast and southern Florida. NON-BREEDING: locally from northern South America south to northern Bolivia, northern Argentina, and southern Brazil, east of Andes; apparently mainly in southern Brazil (Hilty and Brown 1986, Stiles and Skutch 1989, Ridgely and Tudor 1989).
Migration
Migrates mainly along coast. Arrives in southern U.S. by early February (January in southern Florida), northern states and southern Canada in April (Morton and Derrickson 1990). Migrates through Costa Rica August to mid-October and late January-April (Stiles and Skutch 1989). Present in South America mostly September-March (Ridgely and Tudor 1989).
Habitat
A wide variety of open and partly open situations, frequently near water or around towns (Subtropical and Temperate zones, in winter also Tropical Zone) (AOU 1983). South America: congregates in roosts in city plazas and parks (Ridgely and Tudor 1989). In west and formerly in east nests in tree cavities, abandoned woodpecker holes (including those in saguaro cacti), crevices in rocks; in east and midwest now nests in bird-houses and gourds put up by humans.
Food habits
Catches insects in the air; occasionally forages by walking along the ground. Eats ants, wasps, beetles, grasshoppers, dragonflies, etc. Forages often over fields, water, or marshes.
Ecology
During spring and summer populations periodically decimated due to prolonged cold, wet weather, and lack of insect food. Often local in distribution. Forms large roosting flocks at night after nesting season and before southward migration.
Reproductive characteristics
In southern Arizona, eggs are laid in July (Stutchbury 1991). Mating system involves monogamous pairing with extrapair fertilizations by older males. Clutch size is 3-8 (usually 4-5). Incubation lasts 15-16 days, by female. Male guards nest when females goes off to feed. Young are tended by both adults, leave nest 24-28 days after hatching (Harrison 1978), return to nest to roost for a few days after fledging. Usually 1, sometimes 2 broods per season (also reported as only 1 nesting per year). Depending on the location, a few or many of the breeding males are one-year-olds. Most individuals breed for 2-3 seasons. Usually nests in colonies in east and midwest. In natural sites, breeds in single pairs or small groups.
Threats or limiting factors
As a secondary-cavity nester, the Purple Martin has suffered from the introduction into North America of European Starlings (Sturnus vulgaris) and House Sparrows (Passer domesticus), which compete with it for nest sites throughout much of the eastern half of the continent. Without human intervention and management of colony sites, starlings and sparrows can cause local extinction of martins by appropriating their nest cavities and making them permanently unsuitable for martin use. Adverse weather kills more Purple Martins than all other sources of mortality combined. Birds cannot find insects in cold weather, and when such conditions extend >3?4 d, mortality can be substantial. California population is at risk of extirpation by 2031 in part due to starlings and human activities (Airola and Jesse 2003, Airola and Kopp 2009, White et al. 2011). (Tarof and Brown, 2013).
References
- Brown, C. R. 1997. Purple martin. Birds of North America 287: 1–31.
- Behle, W. H., E. D. Sorensen, and C. M. White. 1985. Utah birds: a revised checklist. Utah Museum of Natural History, University of Utah, Salt Lake City. vi + 108 pp.
- Baicich, P. J., and C. J. O. Harrison. 1997. A guide to the nests, eggs, and nestlings of North American birds. 2nd ed. Academic, San Diego. 347 pp.
