What do they look like?

Full grown Purple Martins average eight inches in length. Mature males are dark colored birds with purple glossy feathers. The females and juvenile birds are mostly gray with white patches on the breast and stomach. The head, nape and rump tend to be slightly darker. In their first spring, males resemble females but often show some purple coloration. Purple Martins have similar body shape to other swallows but tend to be larger. In flight they resemble the European Starling, but have a forked tail and longer wings. Also, the birds fly like typical swallows with short glides alternating with very rapid flapping.

(National Geographic 1999)

Where in the world do they live?

The Purple Martin can be found throughout nearly the entire United States east of the Rocky Mountains. Although declining in many western states, it is also found in isolated areas in Canada, Oregon, Washington, California, Utah, Colorado, Arizona, New Mexico and Mexico. The bird is an early spring migrant returning from its winter grounds in South America.

(National Geographic 1999)

What kind of habitat do they need?

Generally, Purple Martins inhabit open areas and prefer an open water source nearby. Martins adapt well in and around people, but are out competed by starlings and sparrows in urban areas. The birds like open spaces to maximize the effectiveness of their incredible flying ability. Having water nearby helps support plentiful insects for food.

(PMCA 2001)

How do they reproduce?

Purple Martins are colonial nesters and are very dependent on man-made nest houses. Once established at a nest location, martins usually come back every year to the same site. The Purple Martin only nests in cavities, often in abandoned woodpecker holes, but today most of the birds use man-made nest boxes. Martins are now entirely dependent on human supplied housing east of the Rockies. Although birds in colonies face increased risk of parasites, and increased competition for resources, reproductive success is not highly dependent on colony size. Males compete for nest sites within the colony. Although there is a lot of physical contact during fights, birds are rarely injured severely. Females are also known to fight over nest sites. The larger the colony, the more the birds fight over territory. After a nest site is chosen and the birds have formed pairs, the male religiously follows the female everywhere. The pair bond is monogamous and both parents build the nest out of grass, twigs and mud. Average clutch size is two to seven eggs and the female incubates them for fifteen days. Both parents feed the young for about one month. The young remain dependent for a few more weeks after fledging during which time they learn to forage by following the parents.

(PMCA 2001, Copley et al. 1999, Davis and Brown 1999, Russell and Gauthreaux 1999)

How do they behave?

After chicks fledge, Purple Martins begin to form large flocks. From late June to early September, Purple Martins often congregate in pre-migratory roosts that may contain one hundred thousand birds or more. Usually all members leave the roost in early morning to feed and return again in the evening. The timing of arrival and departure from the roost is directly related to the amount of light available, which is dependent upon environmental factors such as sunrise, sunset, cloud cover and fog. This behavior maximizes the feeding opportunities for the Purple Martin. Earlier in the summer, birds normally depart from the roost in all directions for feeding purposes. Later in the summer the departures turn southward as migration begins. The birds are willing to travel far for food, often traveling 80-100 kilometers from the roost daily. The birds often follow specific flight corridors when returning to the roost. Some possible advantages to forming these large flocks besides migrational purposes may be thermal regulation, reduced predation risk and possibly enhanced feeding opportunities through information exchange.

(Russell and Gauthreaux 1999)

What do they eat?

Purple Martins only eat flying insects that they catch while in flight. Martins have a diverse diet, which includes: dragonflies, moths, bees, junebugs, flying ants, butterflies, and many more. They do not eat mosquitoes however, as some people like to believe. Martins are extremely agile and fast fliers, which aids them in their quest for food. They normally fly at 45 mph or more. The limitations of their diet and foraging technique leave them at risk of starvation if bad weather persists for three days or more in a row. Heavy rain or cold temperatures are often lethal causing high casualties of Purple Martins.

(PMCA 2001, Coates Manufacturing)

Are they endangered?

Populations of Purple Martins have declined in many areas for two main reasons. One is the reduction of natural cavities due to logging and snag cutting. The second is competition from the English Sparrow and the European Starling, two invasive species who also nest in cavities. Over 1 million people in the United States have erected nest boxes with intentions of attracting Purple Martins, but most are unsuccessful. To successfully attract Martins, the nest box must be placed in an open area and periodically checked for invasive species. Because purple martins nest later than most other bird species, it has been suggested that martin houses are erected late in the season (timing dependent on latitude) so that these man-made cavities become available when they begin nesting. This also reduces the likelihood that martins would be competing with other species for these cavities at that time. Many people enjoy watching the spectacular agility of martins in flight, as well as listening to their pleasant song. Insect control benefits also prompt landowners to erect nest sites for Purple Martins.

(PMCA 2001, Copley et al. 1999)

Contributors

Matthew Thomson (author), University of Michigan: April, 2001. Terry Root (editor), University of Michigan: April, 2001.

References

Coates Manufacturing, "Purple Martin Information" (On-line). Accessed 10/22/00 at http://coatesmfg.com/info.html.

Copley, D., J. Finlay, D. Fraser. 1999. Purple Martins, *Progne subis*: A British Columbian Success Story. Canadian Field-Naturalist: 226-229.

Davis, J., C. Brown. November 1999. Costs of coloniality and the effect of colony size on reproductive success in Purple Martins. The Condor, 101: 737-745.

National Geographic Society, 1999. Field Guide to the Birds of North America Third Edition. Washington, D.C.: National Geographic.

Purple Martin Conservation Association (PMCA), 2001. "Attracting and Managing Purple Martins" (On-line). Accessed 10/22/00 at http://www.purplemartin.org/main/mgt.html.

Russell, K., S. Gauthreaux. September 1999. Spatial and temporal dynamics of a Purple Martin pre-migratory roost. The Wilson Bulletin, 111: 354-362.