Even if you’ve never heard of a purple martin, you’ve probably seen their houses—tall, steepled white birdhouses with many entrances or racks of dozens of gourd-shaped “condos.”
Up close, the birds are striking, with streamlined bodies and calls like laser guns. The adult males are a uniform, iridescent purple-black.
In the eastern United States, purple martins have become completely reliant on humans for housing. The western subspecies sometimes nests naturally in cacti, but the hollow trees eastern martins would historically rely on simply don’t exist anymore in numbers that could support them.
Growing up, some of Courtney Rousseau’s earliest memories were spent watching a neighbor’s colony along the Pungo River.
“Remember sitting and watching on my porch, watching these beautiful birds. I loved their calls. I loved that there was a colony of them,” Rousseau said. “We could watch their antics, feeding and talking to each other. I thought it was the most wonderful thing.’”
Today, as president of the North Carolina Purple Martin Society (NCPMS), Rousseau spends much of her summers travelling the state to promote purple martin conservation, recruiting new landlords, and training old ones.
The purple martin society also manages three public colonies across the Triangle: one at Yates Mill Park, one at the N.C. State University Club, and one at Sugg Farm Park in Holly Springs. Every week, volunteers visit their nesting sites to check on nests’ progress and ensure that the colony is free of mite infestations, invading birds, and dead nestlings.
June means banding season. One by one, nestlings at their colony sites are pulled out of their nests, weighed, and given two lightweight bands: one color-coded to identify where they came from, and one with a unique identification number. This allows researchers to find out where this year’s hatchlings disperse after their yearly migration to South America.
Public banding days also represent an excellent opportunity to raise awareness.
“As an educator and a naturalist, what I love about them is that humans and martins have this long interactive history here,” said John Connors, former president of the Wake County Audubon Society and longtime volunteer, at a banding event earlier this week.
The relationship between humans and purple martins stretches back to before colonization, when Indigenous peoples hung racks of dried gourds to attract the birds. It’s the goal of the purple martin society to make sure that relationship carries on into the future.
At banding events in late June, members of the public, from avid birders to homeschooling groups, crowded into the shade of the banding tent to listen to Connors and other volunteers talk about the martins while getting a front-row seat to the banding process.
A few lucky onlookers were invited to take home bands of their own and even lightly touch the baby birds.
“They’re very comfortable with us working with them,” Connors said. “I can’t think of any other species of bird that is so compatible with teaching, having educational opportunities to actually handle birds.”
Thanks to the efforts of the purple martin society, the breeding population in Wake County has actually been increasing. But across the country, the picture is much more grim: the total population has declined by about 24% since 1966, driven by major losses in northern states. In Maine, for example, the population has plummeted by 95%.
There are a number of factors contributing to the decline of purple martins, including habitat destruction, competition with invasive birds, and regional declines in the insect populations they feed on. Climate change is also shifting the peak availability of insects to earlier in the year, often before purple martins even arrive. That means less food for growing chicks.
In an effort to understand whether or not purple martins can adapt their migration times to combat these changes, NCPMS sites have been chosen to participate in a first-of-its-kind experiment by Columbia University’s Delmore Lab. The two groups transplanted eggs between colonies in North Carolina and Connecticut to study where and when the foster martins migrate using state-of-the-art satellite tags.
If migration timing is flexible, transplanted martins will follow the timeline of their foster families. If it’s genetic, they will migrate at the same time their parents did. Once the experiment is complete, it might yield new conservation tools, like larger-scale transplant operations to rescue northern populations.
“This is a testament to how well we have been working, keeping records, submitting all this stuff to a national database, so they know they have some people down here who are committed to watching their colonies closer. That made it attractive for the Columbia people to come down here,” Connors said. “I’m really proud of that.”
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