Build a birdhouse
Providing food and shelter for birds is becoming increasingly popular not only in residential communities but also in golf-course and institutional settings. One of the most popular birds to attract is the purple martin. In fact, in the last year or so, more than 1 million North Americans put up housing for these birds. Unfortunately, many people have trouble attracting breeding martins to their sites. With a little understanding of how the birds choose breeding sites, you'll have much better luck attracting these graceful birds.
Heading north Purple martins spend the non-breeding season in Brazil then migrate to North America to nest during the summer. East of the Rocky Mountains, the birds depend completely on human-supplied housing. West of the Rockies and in the deserts, they nest primarily as they did before man entered the picture, in abandoned woodpecker nest cavities. In the Pacific Northwest, purple martins often nest in gourds and clusters of single-unit boxes.
Martins are aerial insectivores, meaning they eat only insects that they catch 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. Although you may hear that purple martins consume large quantities of mosquitoes, too, studies by the Purple Martin Conservation Association (PMCA) (Edinboro, Pa.) showed that mosquitoes aren't a typical part of the purple martin's diet. The mosquitoes generally start their activities at dusk, when martins are settling down for the night.
Attracting purple martins Check out your site to ensure you have the proper environment for these birds before going to the trouble to build housing. A main reason people fail to attract martins is that they place the housing incorrectly or in an inappropriate location. Specifically, you must place housing in the center of the most open spot available, about 30 to 120 feet away from human housing and without tall bushes, shrubs or vines. No trees taller than the martin housing should grow within 40-and preferably 60-feet. Generally, the farther you place the housing from trees, the better. (In Southern breeding areas, martins are less particular about house placement.) Height of the housing can range from 10 to 20 feet. Placing the housing near a body of water also improves your chances.
Purple-martin scouts usually show up before the majority of the birds, so it's best to have the house up (see photos accompanying this article)-though not necessarily open for nesting-so they can find it. Then, about 4 weeks after the first martins are scheduled to return to your area, remove anything restricting access. (See subheading, "Competing with other birds," below, for information on why you may need to restrict access.) (Contact your local cooperative-extension agent or the PMCA for dates in your area when purple martins typically arrive. You can reach the PMCA at Edinboro University of Pennsylvania, Edinboro, PA 16444, 814-734-4420, fax: 814-734-5803, firstname.lastname@example.org, www.purplemartin.org. Another good source of information is www.neun.com/cgi-bin/miva?~warren/martin/pmshell.mu.) Then, keep the housing open through August. Martins can arrive as late as the end of June. Then, in July and August, this year's young will begin scouting sites for next year's nesting.
If you have an active site, you can leave housing completely closed until the martins return and land on the units. Once they breed successfully at one site, the same birds return each year.
Competing with other birds Occasionally, other native bird species (such as swallows, sparrows, starlings and bluebirds) try to occupy empty martin housing. If this happens, completely remove their nesting materials and temporarily plug the entrance holes to your martin house with paper cups. Then build some appropriate, single-unit housing on other areas of your property to attract the competing birds. Once you've gotten the other birds to move into their new homes, you can reopen your martin housing. (Once established, martins aggressively defend their homes.)
You also may want to store martin housing inside during the winter, if you don't want to go to the trouble of closing it up. That way, you'll keep paper wasps and squirrels from claiming the unoccupied houses.
Building a house Unless you truly love woodworking, it's probably more convenient to buy a purple-martin aluminum-birdhouse kit rather than building your own. Aluminum homes are typically preferred because they reflect heat. They also are lighter weight than wood kits (which makes moving them easier), and they last longer. Look for kits with units that you can easily raise and lower with easy opening compartments. (You may need to check housing daily to evict nest-site competitors. Doing so doesn't cause martins to abandon their nests or colony site.)
Follow the steps outlined in the photos accompanying this article to begin attracting these acrobatic, vocal entertainers to your site.
Photos by Technical Editor Doug Billings. Birdhouse courtesy of Bill Metz, The Grass Pad (Olathe, Kan.) and Heath Manufacturing Co. (Coopersville, Mich.)
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