Photo: Purple Martins, John James Audubon
Purple Martins Thrive in Northern Virginia with a Little Help from Their Neighbors
Jessica Bigger
Mike Bishop grew up on a beautiful large piece of property in Spotsylvania, Virginia. During his childhood, Bishop and his father would put up nest houses for bluebirds and monitor the nests each year. After successfully attracting bluebirds to his family’s land, Bishop decided to put up a Purple Martin (Progne subis) house to see what would happen. After a year or two several Purple Martins had taken up residence. “We got three colonies,” said Bishop.
Today, Bishop and a group of volunteers monitor around 22 Purple Martin houses throughout Northern Virginia. After retiring, Bishop decided to get back into building special nest boxes for Purple Martins that reduce infestation by starlings and sparrows; an improved design from J.L. Wade’s aluminum version, which was quite prone to starling and sparrow infestation.
He built his first Purple Martin nest box in one of Westfield High School’s athletic fields. It took three years to attract Purple Martins to that location but now Westfield High School has three established colonies. Bishop founded the Northern Virginia Purple Martin Initiative in 2015 to increase and strengthen the Purple Martin population in the area. The organization not only builds and monitors nest boxes for Purple Martins, but volunteers also build houses for other cavity-nesting species, including woodpeckers, Chimney Swifts, Great Crested Flycatchers, the Tufted Titmouse, chickadees, wrens, Eastern Bluebirds and Tree Swallows.
Because of Bishop and many other bird advocates across the country, the Purple Martin’s population is stable and of low conservation concern. Purple Martins nest in open fields, usually near a water source. Since most of their habitat provides little nesting opportunity, this species has always depended on human assistance. People have been providing homes for Purple Martins for centuries, beginning with Native Americans, who used to build nest cavities out of gourds. They created a symbiotic relationship with the birds. In exchange for providing nesting habitat for the Purple Martins, the birds would warn the Native Americans of owls and hawks hunting nearby.
Purple Martins not only warn residents about birds of prey, they also keep the insect population at bay, which protects their gardens and makes relaxing outside a bit more enjoyable.
Purple Martins are social species. They love hanging out near people, and enjoy visiting other colonies nearby. Reston National Golf Course has a nest box near Links Pond that houses one colony of five birds. Reston resident and Fairfax County Coordinator for the Virginia Bluebird Society's nest box monitoring program, Helaine Krob, lives on the golf course and monitors the nests.“ Yesterday, we saw 12 of them up in the air flying around together. Swooping and chatting and calling. So, there is a visiting colony and after they hang out, they head home. Our colony visits another colony in the evening, and around 8:30 pm they will all return to the apt house,” explained Krob.
There are a variety of insects Purple Martins will forage for: beetles, flies, dragonflies, damselflies, leafhoppers, grasshoppers, crickets, butterflies, moths, wasps, bees, caddisflies, spiders, cicadas, termites and mayflies. They will also hunt for insects at a much higher altitude than swallows. To help them digest the insect exoskeletons, Purple Martins will eat small amounts of gravel. Some nest watchers leave crushed eggshells, which also aids in digestion.
In Northern Virginia, Purple Martins generally arrive at the end of March. Each pair raises one brood per breeding season. Last year the Reston National Golf Course Colony raised three young. At the end of August, they make the 3000-mile journey down to the Amazon Basin in South America to overwinter, and then make the 3000-mile trip back to North America the following breeding season.
If you want to get involved in citizen science visit the Northern Virginia Purple Martin Initiative Facebook Page or the Purple Martin Conservation Association.
Sources:
https://www.youtube.com/watch?v=NDLu-aaVIjY&t=634s
https://www.allaboutbirds.org/guide/Purple_Martin/overview