Hobbies And Interests
Biology
The largest member of the swallow family, purple martins (Progne subis) measure just over 7 inches in length. Like other birds, the species does not immediately display adult plumage, a trait known as delayed plumage maturation. For two years, the young of both sexes resemble the female, with a brownish-purple back and gray throat and breast. Adult males become entirely glossy purple-black and adult females display more purple on their upper surfaces.
Purple martins are aerial insectivores, consuming a variety of insects and spiders. For years, nest box manufacturers promoted the species as the "mosquito-eating bird," claiming one bird could consume up to 2,000 mosquitoes per day. A three-year study by the Purple Martin Conservation Association contradicts these claims, finding that purple martins rarely, if ever, feed on mosquitoes. Purple martins do, however, actively consume many insect species classified as pests, including Japanese beetles, stinkbugs, midges and flies.
Migration
Purple martins spend the nonbreeding season in Brazil and then migrate to North America to nest. The first martins to arrive each year are known as scouts, generally older breeding males returning to select the best nest compartment. Purple martins show a high degree of nest fidelity, often returning to the sites where they previously successfully bred. Since 1998, the Purple Martin Conservation Association has collected and disseminated purple martin migration data from across the bird's range in North America. One component, the Scout Arrival Study, utilizes citizen reports of scout sightings. In Arkansas, dozens of citizens have reported the arrival of 2011 scouts, as early as February 12th. The majority of females and more inexperienced birds generally arrive in Arkansas four to eight weeks after the scouts.
Nesting
During the breeding season, purple martins are monogamous, colony nesters, preferring to nest in close proximity to one another. In the eastern half of the continent, the species depends entirely on human-supplied nesting cavities for breeding. Pairs generally incubate four to five eggs for a period of 15 days. The young fledge after approximately 28 days, but remain with their parents for up to two additional weeks. In Arkansas, birds leave their nesting sites in July, but are often seen through early September, as they migrate through to wintering grounds.
The Purple Martin Conservation Association estimates that over one million North Americans maintain housing for purple martins -- those successful at attracting martins are termed landlords. A number of Arkansas' active martin landlords avail themselves to mentor new hobbyists. The association enlists these landlords to monitor their nests and collect data that is used to determine range-wide reproductive success and annual population trends.
Viewing Opportunities
Highly social birds, purple martins congregate in large, communal roosts after departing the nesting colony. These roosts, both in North America and Brazil, are typically in close proximity to large bodies of water. Arkansas is home to one of the continent's larger purple martin roosts, Bird Island in the middle of Lake Ouachita. The island is the subject of an award-winning documentary filmed by the students of Mountain Pine High School, who successfully nominated the site as an Audubon Important Bird Area. Now a popular tourist destination, Bird Island is used by an estimated 8,000 to 50,000 purple martins between July and early August each year.