Purple martins are the biggest swallows in North America, and they are about 20.3 cm long. They weigh around 56 g and their wingspan is approximately 45.7 cm. Males are a little bit bigger, and their feathers are shiny and such a dark purple that they are almost black. Their heads and backs are shinier than their wings. Females are gray or gray-blue with darker wings and darker feathers on top of their heads. They have white breasts smudged with different shades of gray. Eastern females are darker overall than eastern ones. Their dark black-brown bills are 8.2 mm long in males and 8.5 mm long in females. The inside of their mouth is yellow in young birds and orangey-brown in adults. Their legs and feet are black-brown and their eyes are dark brown. (Brown, 1997; Layton, 1972; Wade, 1966)
Young purple martins are gray to black and have white bellies and gray streaks on their breasts. Young look different from adult females because their bellies are much more obviously white rather than gray. When young purple martins fly, their tail may have a small fork, but adult tails are wider and definitely forked. (Brown, 1997; Layton, 1972; Wade, 1966)
Purple martins can be found across North and South America, depending on the season. They live and breed in North and Central America and spend the winter in South America. In the summer, they can be found as far north as Alberta, Saskatchewan, and Manitoba in Canada. They breed across the eastern half of the United States, and also might be found along the coast of the Pacific Ocean or along California's Baja Peninsula. In the winter, they can be found in Colombia, Venezuela, Guyana, Suriname, Ecuador, Peru, Brazil, Bolivia, Paraguay and Argentina. They live east of the Andes mountains, especially in Bolivia and parts of Brazil. (Brauning, 1992; Brown, 1997; Johnston, 1966)
Purple martins prefer to live in open spaces close to water, because they find lots of insects to eat near wetlands, swamps, and wet meadows. Purple martins are very used to humans and live in man-made birdhouses designed specially for them. Before martin houses, they lived at the edges of forests, in mountain forests, and deserts. Some purple martins in the western United States still live in these natural habitats, but most nest in man-made martin houses. Purple martins are usually found at elevations between 100 m and 4,000 m. (Brauning, 1992; Brown, 1997)
When they are traveling between summer and winter locations, they rest in different kinds of habitats. These could be cities, open areas, or high mountains in Venezuela and Columbia. They fly along the coast and cross the Gulf of Mexico. In the winter in South America, they stay in rainforests, farm fields, clearings, and sometimes cities. (Brauning, 1992; Brown, 1997)
One male and one female purple martin form a pair each year to breed and raise their young. Males arrive first to the breeding location and find two possible nest locations to show off to females. Males are very territorial and will aggressively defend the nest sites from other males. Males fly out from their nests in a wide arc, swoop back inside the nest, and then pop their head out singing. This is supposed to attract females, who actually pay more attention to whether the nest is good or not. After pairs form, males defend their nest site and their partner. (Brown, 1979; Brown, 1997; Johnston and Hardy, 1962)
Once purple martins are in pairs, they start building a nest. They build the nest about one month before they female lays eggs. They use green leaves, grass, sticks, paper, mud, and feathers. Scientists aren't sure why they use green leaves in the nest. Females do most of the building while males gather nest materials and defend the spot from other purple martins. They used to build all their nests in holes in trees, but now they mostly nest in man-made "martin houses." (Brown, 1978; Brown, 1997)
Purple martins breed between May and June. Females lay 3 to 8 white oval-shaped eggs, but usually lay 5. The eggs are about 2.4 cm long and 1.7 cm wide. They take 15 to 18 days to hatch. The chicks can fly after 26 to 31 days and travel in a family group. The group comes back to the nest to sleep for several days. After 7 to 10 days, the chicks are able to survive on their own and leave the family group. Purple martins can reproduce when they are 1 year old. (Brown, 1978; Brown, 1997)
Females keep the eggs warm for 15 to 18 days until they hatch. If females leave the nest, males take over keeping the eggs warm. However, this doesn't happen often. When chicks are born, they have no feathers, and can't open their eyes or feed themselves. After the chicks hatch, females keep them warm in the nest for 10 more days. Parents feed the young until they can fly, and for 5 to 7 days after. Both males and females feed the chicks undigested food they throw up into the mouths of the chicks. If the piece of food is too big for the chick to swallow right away, the parents take it out of their mouth right away. After two weeks, females stop sleeping with the chicks because it is no longer necessary. (Alsop III, 2002; Brown, 1980; Brown, 1997; Layton, 1972)
Purple martins can live up to 13 years and nine months. If there is severe weather for 3 to 4 days, the number of insects decreases quickly and they sometimes starve. They can also die from the parasites in their bodies. (Brown, 1997; Layton, 1972)
Purple martins are are active during the day and are most active at dawn and dusk. They live together in colonies, which are very large groups of birds. Although mating pairs are very protective of their territory, they become loyal to the whole group when they join a colony. During the day, they fly around in pairs or stay in their colonial groups. In a colony, the whole group works together to improve their reproductive success, but disease and competition are more common. Colonies are social and 3 or more purple martins from the colony go out and explore their surroundings together. This involves visiting other colonies, scoping out potential food sources, and visiting nearby streams and swamps. Purple martins search for food together in large flocks. When the groups find food, they call over the rest of the colony to come feed. The whole colony flies back to South America at the end of the summer. Tens of thousands of purple martins might fly back together at the same time. (Alsop III, 2002; Johnston and Hardy, 1962)
Purple martins can get aggressive if they are threatened. For example, they defend themselves by pecking and flapping their wings, trying to get the intruder to leave. They also sing to alert other purple martins, or open their mouth wide at the possible threat. They might also lunge or snap their bills to intimidate. (Alsop III, 2002; Johnston and Hardy, 1962)
Purple martins often return to the same nesting site as the year before. Scientists don't know how far they go looking for food, but it is likely a long ways because they can fly very far. They travel 2.8 to 664 km to get back to their nests. (Brown, 1997)
Purple martins communicate by singing and body language. They make 11 different noises that are used for mating, warning, and teaching the young to fly. Males attract females by singing and showing off. Young purple martins make noises that sound like "choo-choo" to get their parents' attention if they need protection. Parents make the same noise to bring their chicks together and bring them safely back to the nest. Females make the noise "choo" to lead their young when they are learning to fly. Purple martins make "zwarck" calls for serious alarm, and often dive straight down at the threat while making this noise. Males make the sound "hee-hee" to fight off intruders. "Zweet" are warnings of possible threats or other excitement between purple martins. "Cher" noises are for day-to-day communication and "chortle" noises are for excitement situations. Males attract females by singing ‘croak songs,’ which also warn other males to stay away from their territory. They also make a clicking sound with their beak during courtship. They make ‘subsongs’ while feeding and before migrating. Males in stable colonies perform a 'dawnsong' win the early morning, which is a lot of different sounds. Like all birds, purple martins use their senses of sight, sound, smell, taste, and touch. (Brown, 1978; Brown, 1984; Brown, 1997; Johnston and Hardy, 1962; Morton, 1985)
Purple martins primarily eat insects, which they capture in flight or grab from leaves or off the ground. They prefer to eat fruit flies, mosquitoes, wasps, beetles, ants, grasshoppers, cicadas and dragonflies. They can eat 400 flies or 2000 mosquitoes in just one day. (Brown, 1997; Campbell Finlay, 1976; Layton, 1972)
Purple martins rarely eat spiders and prefer any other kind of insect. They diet is about 23% wasps and bees, 16% flies, 15% assorted bugs like stink bugs and black bugs, and 12% were beetles. Purple martins also eat butterflies and moths and prefer dragonflies. Young purple martins prefer to eat dragonflies over other insects. (Brown, 1997; Campbell Finlay, 1976; Layton, 1972)
Weather affects the number of insects available, so it definitely affects purple martins. When it's cold outside or very windy, the number of insects decreases. When it's hot outside, there are plenty of insects to eat. In August, the most insects are available to eat, which helps them get ready for their long flight south. Purple martins consume water in flight by skimming over water. (Brown, 1997; Campbell Finlay, 1976; Layton, 1972)
The most common predators for purple martins are owls and snakes which prey on both adults and juveniles. Owls attack while the birds are inside the nest. Owls grab the nest and shake it, which disorientates the purple martin inside. The bird then tries to slip out of the entrance hole where the owl grabs it with its claw. Humans can help prevent these owl attacks by attaching curved rods over nest entrances so that owls cannot perch atop the martin houses. Owls have also been known to reach their claws into martin houses to grab any unfortunate purple martin. (Brown, 1997; Kostka, 2000; Layton, 1972)
Predators like snakes or raccoons are able to climb birdhouse poles and make their way to the entrance cavities. They pull out any adult birds and then proceed to eat the eggs. Rat snakes are the most common snake predators. Hawks and blue herons are the only two predators that prey on purple martins in the air. House cats prey on purple martins when they are on the ground in search of nesting material. Squirrels also prey on purple martins by climbing up the nest and entering the cavity. The squirrel then kills the young, breaks up all the eggs and can even take over the nest to raise its own young. (Brown, 1997; Kostka, 2000; Layton, 1972)
An interesting behavior that avoids predators is constant nest cleaning. Purple martin parents eat or remove any body waste from the nest that smells like the chicks. They also warn each other about predators by making the "zweet" call and dive bomb their attackers. When living in a colony, purple martins are able to quickly discover predators. If a predator approaches a colony, purple martins gather in a crowd to confuse them. They generally only attack if the predator comes within a few meters of their personal nest or young. (Brown, 1997; Kostka, 2000; Layton, 1972)
Purple martins are predators, prey, competitors, and hosts to parasites. They are insect-eaters that control numbers of pest insects. Mites that live outside their nests can decrease the number of chicks and even cause abandonment of a colony if an outbreak happens. Other parasites that live on them are ticks, beetles, louseflies, fleas, and bowflies. (Brown, 1997; Kostka, 2000; Layton, 1972; Moss and Camin, 1970; Wade, 1966)
Purple martins compete for nesting sites with house sparrows and European starlings. Starlings corner purple martins in their own nests and will fight, even to the death. House sparrows and European starlings are both invasive species in the United States and often out-compete native purple martins for nesting habitat. (Brown, 1997; Kostka, 2000; Layton, 1972; Moss and Camin, 1970; Wade, 1966)
There are no known adverse effects of purple martins on humans.
Purple martins consume large quantities of species that are pests to humans including flies, stink bugs, clover weevil beetles, and mosquitoes. They are beautiful birds that are enjoyed by many bird watchers. (Wade, 1966)
Purple martins are a species of "least concern" on the IUCN Red List, have steady numbers, and live in a wide area. However, they are a "species of concern" on the U.S. federal list, and several groups are working to conserve their natural habitat. Their numbers have declined some in Canada. They are considered at risk in British Columbia, so special nesting boxes are being set up for them. In the places they live that are farther north, local groups of purple martins have died from severe weather. Purple martins struggle because of nest competition with invasive house sparrows and European starlings. (Brown, 1997; Fraser, et al., 1997)
Nadine Snyman (author), University of Alberta, Augustana Campus, Doris Audet (editor), University of Alberta, Augustana Campus, Rachelle Sterling (editor), Special Projects, Catherine Kent (editor), Special Projects.
U.S Department of Agriculture. Purple Martin Birdhouse. 204,523. New York, NY: Armond Industries, Inc.. 1971.
Alsop III, F. 2002. Purple Martin. Pp. "464" in R Greenberg, J Hamilton, eds. Birds of Canada, Vol. I, 1st Edition. Toronto Ont.: Southern lights Custom Publishing.
Brauning, D. 1992. Atlas of Breeding Birds in Pennsylvania. Pittsburgh: University of Pittsburgh Press.
Brown, C. 1978. Post-Fledging Behavior of Purple Martins. The Wilson Bulletin, 90/3: "376-385". Accessed November 01, 2010 at http://www.jstor.org/stable/4161087.
Brown, C. 1980. Sleeping Behavior of Purple Martins. The Condor, 82/2: "170-175". Accessed November 01, 2010 at http://www.jstor.org/stable/1367472.
Brown, C. 1979. Territoriality in the Purple Martin. The Wilson Bulletin, 91/4: "583-593". Accessed November 01, 2010 at http://www.jstor.org/stable/4161272.
Brown, C. 1997. Birds Of North America. Philadelphia, PA: The American Ornithologists/ Union and The Academy of Natural Sciences.
Brown, C. 1984. Vocalizations of the Purple Martin. The Condor, 86/4: 433-442. Accessed October 03, 2010 at http://www.jstor.org/stable/1366823.
Campbell Finlay, J. 1976. Some Effects of Weather on Purple Martin Activity. The Auk, 93/2: "231-244". Accessed October 31, 2010 at http://www.jstor.org/stable/4085041.
Davis, J., C. Brown. 1999. Costs Of Coloniality And The Effect Of Colony Size On Reproductive Success In Purple Martins. The Condor, 101/4: "737-745". Accessed September 16, 2010 at http://www.jstor.org/stable/1370060.
Fraser, D., C. Siddle, D. Copley, E. Walters. 1997. The Return of the Purple Martin in British Columbia. Wildlife Branch, British Columbia Ministry of Environment, Lands and Parks, 1: "279-282". Accessed November 07, 2010 at http://www.env.gov.bc.ca/wld/documents/ce07fraser2.pdf.
Johnston, R. 1966. The Adaptive Basis of Geographic Variation in Color of The Purple Martin. The Condor, 68/3: "219-228". Accessed November 07, 2010 at http://www.jstor.org/stable/1365555.
Johnston, R., J. Hardy. 1962. Behavior of the Purple Martin. The Wilson Bulletin, Vol 64, No. 3: "243-262". Accessed September 25, 2010 at http://www.jstor.org/stable/4159068.
Kostka, K. 2000. Owl Guards for Gourds: A Way to Protect Martin Gourds from Aerial Predators. Purple Martin Update, 9/4: "1".
Layton, R. 1972. The Purple Martin. Jackson, Missisippi: Nature Books Publishers.
Morton, E. 1985. Vocal Imitation in a Captive Purple Martin. The Wilson Bulletin, 97/3: "392-395". Accessed November 01, 2010 at http://www.jstor.org/stable/4162123.
Morton, E., K. Derrickson. 1990. The Biological Significance Of Age-specific Return Schedules In Breeding Purple Martins. The Condor, 92: "1040-1050". Accessed September 25, 2010 at http://www.jstor.org/pss/1368740.
Moss, W., J. Camin. 1970. Nest Parasitism, Productivity, and Clutch Size in Purple Martins. Science, 168/3934: "1000-1003".
Stutchbury, B., J. Hill III, P. Krame, S. Rush, S. Tarof. 2009. Sex And Age-Specific Annual Survival In A Neotropical Migratory Songbird, The Purple Martin (Progne Subis). The Auk, 126/2: "278-287".
Turner, A. 1985. Swallows. Pp. "332-335" in C Perrins, A Middleton, eds. The Encyclopedia of Birds, Vol. I, I Edition. New York: Facts on File.
Wade, J. 1966. What You Should Know About The Purple Martin. Griggsville, Illinois: J. L. Wade.
Wagner, R., M. Schug, E. Morton. 1996. Condition-dependent control of paternity by female purple martins: implications for coloniality. Behavioral Ecology and Sociobiology, 38/6: "379-389".
Williams, J. 1987. Field Metabolism and Food Consumption of Savannah Sparrows during the Breeding Season. The Auk, 104/2: "277-289". Accessed November 01, 2010 at http://www.jstor.org/stable/4087034.