TAHLEQUAH, Oklahoma – Purple martins will soon start to make their appearance in the Midwest, delighting state residents who have "houses" set out for them.
Laura Hulbert, a Tahlequah resident and birding enthusiast, said martins are interesting birds with history that can be tied to Native Americans and gourd bird houses.
“Something that’s kind of relevant to Cherokee County is that back before Europeans settled here, Native Americans would actually hang up empty gourds for purple martins,” said Hulbert. “They are secondary cavity nesters, which means they don’t create their own hole in a tree or some sort of cavity. Usually they will nest after a woodpecker makes a hole in a tree.”
Hulbert said purple martins are known to be a colonial nesters, where multiple nesting areas will be in the same building, creating a large colony. In late summer, during which their young birds hatch, the local population will roost together, creating a large flock of 15,000-30,000 birds, which meteorologists often have to take into consideration.
“When you have 30,000 birds leaving one tree or several trees that are close together all at the same time, it actually shows up on the weather radar,” said Hulbert. “When they disperse to go about their daily business, all of them leave at the same time, and it shows up on the weather radar map like a doughnut that’s just like bursting out.”
The birds can be vulnerable to cold and rainy weather, and when people use pesticides, they kill off their food source of flying insects.
Jim Harman, a Fort Gibson naturalist, said purple martins don’t have as much of a food source when insecticides are used or when a habitat changes from an open area to one with trees.
“They like to feed, on at a certain stage just before they’re young fledge, a lot of dragonflies, and we don’t have [as many] dragonflies that we used to have, so we have cut down on their food supplies,” said Harman. “We do so many things that we think we’re doing good, but we don’t know the bad our good will do in the future.”
Jeff Kelley, a University of Oklahoma biology professor, said they are aerial insectivores, which are birds that eat insects and catch them when flying.
Purple martins will eat a lot of dragonflies, butterflies, flying ants, beetles, and any other flying insects. Kelley said people will often put up purple martin houses because of the myth that they eat mosquitoes. But those are normally smaller insects than what purple martins eat.
“They’re really unique in the sense that every purple martins that you see – at least in the eastern part in the U.S. – nests in and was raised in a house provided by a person,” said Kelley.
Due to the codependencies purple martins have with humans, Kelley said it’s like there is a connection between these birds and humans.
Around September, Kelley said, the birds will migrate to Brazil and the Amazon rainforest and will stay there for about half a year.
“You have this really interesting setup, where these birds are wild birds that migrate all over the hemisphere, but at the same time, they’re dependent upon the houses that we put up in our backyards,” said Kelley.
Hulbert said purple martins will leave the most southern region in late December or early January, and they will then start to be seen in the southern United States in mid-January. She said purple martins will normally start to appear in Oklahoma in mid- to late April.
The myth of how purple martins will return to the same nest is true, in a sense. Kelley said a bird may not come back to the nest it originally fledged from, but after becoming an adult and starting to breed, purple martins will come back yearly to a specific spot of their choice.
Kelley said there are specialized houses some people will use for the martins, and these will have four openings on two sides of the house. Most of the time, Kelley said, the house will have a specialized opening that will keep invasive species from entering.
The breeding ground of a purple martin is normally an open area without many trees, such an open lawn or at the edge of a lake.
Kelley said the birds have several threats to deal with on their breeding grounds, including extreme temperatures, snakes, nest parasites, and birds in the raptor family that will catch purple martins as they leave the nest. Owls that will perch on the houses and reach in to grab the chicks.
To prevent parasites from infecting purple martins nests, Kelley said the Purple Martin Conservation Association suggests that people to clean out the nests in purple martin houses before the next batch arrives.
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