The purple martin is one of Tennessee's most beloved summer residents. And the feeling is mutual.
In the eastern U.S., the purple martin depends almost entirely on man-made birdhouses for nesting sites.
The relationship between man and martin began centuries ago, when Native Americans first began hanging dried, hollowed gourds cut with small circular doorways near their crops. Their goal was to attract the cavity-nesting, insect-eating birds to help control pests. The largest swallow in North America, the purple martin is capable of consuming countless insects, though it is a widely reported myth that the bird eats up to 2,000 mosquitoes a day.
According to the National Audubon Society, mosquitoes make up only a fraction of the purple martin's diet, as the bird tends to do its in-flight foraging 150-500 feet off the ground, which is higher than the pesky insect swarms.
Still, the purple martin is a welcome sight each summer, with its iridescent blue-black plumage and its dazzling aerial acrobatics. When it hunts, the bird flares its tail and zips sideways or upwards, while increasing its speed up to 40 miles per hour.
Want to attract the martin to your property?
In the western U.S., purple martins nest in tree cavities; however, in the east, they require man-made birdhouses.
"Typically when you see a birdhouse, it's designed for one nesting bird," says Diane Whitman, owner of the East Brainerd location of Wild Birds Unlimited nature shop. But purple martin structures, shes says, are "designed like little apartments."
The purple martin is colony-nester, so nest boxes must be large and comprise multiple compartments. Or, as in the the case with gourds, which are still commonly used, the individual hollowed-out gourds must strung close together on one wire.
Moreover, Whitman says, the purple martin requires about an open acre of land and a nearby water source.
Color: Adult males are iridescent blue-back overall, with brown-black wings and tail. The male is the only North American swallow with a dark belly, making in-flight identification easier. Females and immatures are a duller blue-black, with some gray on the head and chest and a whitish, speckled belly.
General size: Larger than a sparrow but smaller than a robin.
Length: 7.5-7.9 inches
Weight: 1.6-2.1 ounces
Wingspan: 15.3-16.1 inches