Purple martins are on their way
March 21, 2015 at midnight
According to the U.S. Department of Agriculture, interest in birding has grown to a $5 billion per year interest. One bird that is quite interesting to have in our yards is the purple martin. It is said that Native Americans discovered they could lure martins into their villages by hanging up gourds with holes cut on the side. Over hundreds of years, martins gave up their natural way of living.
Migration begins in late January
Purple martins spend their winters in Brazil and begin arriving in the United States in late January. They enter the southern states to nest, from Florida and Texas into the Midwest, up into the eastern seaboard and into southern Canada.
Purple martins, Progne subis, are of the swallow family and live in colonies. They are 71/2 inches long and weigh 1.9 ounces with an 111/4-inch wing span. The average purple martin lives two to five years with some living as long as six to seven years.
Purple martins are sexually dimorphic, meaning males and females have different plumage. Males are dark, glossy blue-black with a distinct notched tail. Females are duller in color and have a grayish color on the hind neck with the throat, breast and flanks being dusky brown. The center of the female belly is paler. Martins are vocal and "chur" or give a "zwrack" or "zweet" call.
Breeding season is a 70-day cycle. Martins are monogamous meaning they pair for the breeding season. Both male and female build the nest made of grass, mud and twigs. The female lays two to seven pure white eggs. She will incubate the clutch for 15 to 16 days and then the young will hatch.
Both parents feed the young for 26-32 days, until the young fledge - or learn to fly out of the nest. The young will remain dependent on the parents for food and life skills for the next one to two weeks after fledging.
Purple martins east of the Rocky Mountains are dependent on humans to provide their nest boxes or houses in order to breed. The type of housing used depends on personal preference.
Houses can be made from wood, aluminum, or plastic. The compartments in the house should be a minimum of 6 by 10 inches, but 7 inches by 12 inches is preferred for better protection from weather and predators.
Entrance holes should be 1 inch above the floor of the compartment and can be 13/41/8
Gourds can also be used. They can be plastic or natural. Gourds should have a minimum depth of 10 inches. Martins prefer natural gourds, which require preparation and maintenance.
Martins like houses placed in the center of an open area away from trees, and the houses should be 10 to 25 feet off the ground. There should be no trees taller than the martin housing within 40 feet. Bushes, vines and shrubs should be kept away from the poles.
The houses should be on poles that are easy to lower for cleaning and houses should be closed or put inside during the winter to keep out wasps, squirrels and competing birds. Martin housing should be 30 to 120 feet from human housing.
Diet and eating habits
Martins are aerial insectivores. They eat flying insects that are caught in flight. Their diet includes dragonflies, damselflies, flies, midges, mayflies, stinkbugs, leafhoppers, Japanese beetles, June bugs, butterflies, moths, grasshoppers, cicadas, bees, wasps, flying ants and ballooning spiders. Notice mosquitoes are not mentioned.
Martins are daytime feeders and feed high in the sky. Martins are vulnerable to starvation after two to three days during extended periods of rainy weather or drought or extreme heat, which reduces or eliminates insect flight.
Purple martins have several predators. The aerial predators include owls, Accipiter hawks, crows, falcons and kites. Ground predators include rat snakes, opossums, raccoons and squirrels. Starlings and sparrows compete with martins for nesting. They will fight martins, kill their nestlings or break eggs. Pesticides also pose a threat to martins.
Beneficial to gardens
Purple martins are beneficial to gardens as seen by their diet. Educate yourself through the Purple Martin Conservation Association and the Purple Martin Forum.
They offer tips to attract martins such as choosing the best location for housing, opening the house at the right time, keeping the house safe from predators and having a good pole for lowering the house when not in use.
Bird watching is a relaxing and entertaining hobby. Why not consider providing a home to this gardening friend this spring?
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or firstname.lastname@example.org, or comment on this column at VictoriaAdvocate.com.