by Eileen Berger
Although most bird lovers have heard of purple martins, they may not know much of the birds’ history or unique needs during nesting season. Steve Woodward, owner of Wild Bird Center in Ft. Worth, Texas presented an interesting and informative program about the birds Monday night to the members and guests of Indian Trail Master Naturalists.
Purple martins(Progne subis) are the largest of the swallows. Their whole existence is spent in the air, rarely if ever touching the ground. Their tiny feet allow them to perch but are not useful for walking. They are insect eaters, but do not eat mosquitoes, contrary to what you may have heard or seen advertised. Purple martins migrate each winter to Brazil, returning to the same nesting area each spring. The purple martins in Texas are part of a large group which no longer nest in naturally-occurring cavities such as woodpecker holes. They need homes provided by humans, and prefer these homes to be near people. Native Americans were known to hang gourds in their settlements as homes for these beautiful blue-black birds.
In Colonial America, travelers would judge the prospective quality of an inn based on the tavern owner’s purple martin houses. A poorly-maintained martin house might mean a less than ideal place to spend the night.
Purple martins only raise one nest of babies each year. The males arrive first from Brazil, survey the availability of homes in their former neighborhood, and wait for the females and yearlings to arrive. Both the male and female feed the 2-8 young for 4weeks, after which the baby birds are able to begin catching insects in aerial forays just like the adults.
Snakes, raccoons, owls, and hawks are the naturally occurring predators of these birds. However, English or house sparrows(Passer domesticus), and European starlings(Sturnus vulgaris) are equally if not more destructive. If a homeowner wishes to attract purple martins to his yard or acreage, he will need to be vigilant in observing the house, and implement protective measures to deter these predators.
Choosing the right location for placement of a housing system is very important. It should allow 30-40 feet of open space measured from the drip line of mature trees, and be 20-30 feet away from a dwelling but not more than 120 feet from people. Small trees do not bother them. The right choice of a home and pole system will make it easier to clean the house and monitor the birds. Mr. Woodward recommended an aluminum house with a winch-operated pole for raising and lowering the house. Keep in mind that during the nesting season, your house will be full of birds, making it that much heavier and more dangerous to raise and lower. Telescoping poles or lanyard systems are not as satisfactory as the winch system. He warned against using cheap plastic houses which can blow away or be destroyed in a heavy storm.
Attracting the birds to your house is another challenge. Some enthusiasts play a compact disc entitled Dawn Song early in the morning to lure the males to the house. Placing a decoy purple martin on the house is another suggestion. Some “landlords” place nest-building materials in a few of the rooms.
Several companies sell sparrow traps to remove sparrows from the area. It is not against the law to “dispatch” house sparrows, and many bird enthusiasts recommend it as the only permanent way to rid an area of the invaders. Starlings can be discouraged by buying a house with starling-resistant entrances shaped like a crescent, but that does not discourage sparrows. Wrapping the pole with a tangle of bird netting is the best way to catch rat snakes which can navigate around the baffles used on poles to prevent raccoons. Purchasing houses with deep rooms works best to deter raptors such as hawks and owls.
A local group of enthusiasts meet monthly in Grand Prairie. Their web address is www.purplemartinlandlordsofnorthtexas.com.