KENNEBUNK — Seven years.

That’s how long the York County Audubon waited for purple martins to arrive at the Madelyn Marx Preserve. In 2017, the nonprofit built the special housing these birds need for their nests. Every spring, treasurer Kathy Donahue spent early mornings in the marsh, playing a recording of their song on her phone to attract the species.

By 2024, she had given up hope.

That year, she got the call.

“Lo and behold,” Donahue said. “We had martins in all the holes.”

That first year, there were six nests. Last year, the York County Audubon added six more houses, and purple martins took up residence in all 12. This year, the nonprofit again doubled the capacity, and 22 of 24 nests were occupied in mid-July. Volunteers and students counted 89 chicks on a visit this month.

Those numbers are a big deal in Maine, where purple martins are a species of special concern and experts say their numbers have plummeted by more than 90% in recent decades. Reviving this vulnerable population relies on both citizen science and academic research.

“This species is in this conservation situation because of what humans have done,” said Joe Siegrist, president and CEO of the international Purple Martin Conservation Association. “But we hold the key to saving it.”

Anna Forsman, an assistant professor of biology at Colby College, takes a blood sample from a purple martin in Kennebunk on July 14. (Gregory Rec/Staff Photographer)<?xml version="1.0"?> Purchase this image A RENEWED EFFORT

Muck boots squelched in the Madelyn Marx Preserve, a coastal salt marsh managed by the Kennebunk Land Trust. It was 6 a.m. and already humid on July 14.

Anna Forsman, an assistant professor of biology at Colby College, led three students from her lab down the soggy path. They walked with Donahue and other volunteers from the York County Audubon.

On top of two poles in the middle of the marsh were 24 white plastic gourds.

As the group approached, the trills became louder.

Historically, purple martins — the largest member of the swallow family and known for their blue-purple iridescence — nested in cavities, such as rock crevices or woodpecker holes in trees. In part because of habitat loss, their colonies east of the Rocky Mountains now rely almost entirely on manmade homes.

The birds flitted and swooped as students and volunteers set up a work station for the morning.

The day’s task was to band and sample as many adult purple martins as possible. Forsman is an ecological immunologist, which means that she studies how immune systems develop and function in nature. She and her students have been extracting DNA and other information from fecal and blood samples from the birds to learn more about their health and diet.

“When we have the opportunity to get our hands on these birds, we want to get as much data as possible,” said Forsman, who started working with purple martins at the University of Central Florida and moved to Maine three years ago.

Colby College junior Dorothy Liu retrieves a purple martin from a nest held by Kathy Donahue in a marsh in Kennebunk on July 14. (Gregory Rec/Staff Photographer)<?xml version="1.0"?> Purchase this image

The students set up tables with scales and other tools for taking measurements, as well as vials and slides for samples. In the meantime, volunteers from York County Audubon waited at the ready with their own instruments — paint rollers.

When a purple martin entered the gourd to feed the chicks inside, a volunteer would rush forward and block the entrance with the roller. Dorothy Liu, a rising junior studying computational biology, reached inside the nest and gently wrapped the bird in a canvas bag to be analyzed.

Liu placed the bird on a scale, while other students secured a small band on its leg and took measurements of its wings and head. Forsman cradled the bird in one hand as she drew blood. She added a second, bright orange band so the volunteers at this site would easily recognize the bird if it returns in future years.

Each of her students has a different focus.

Last year, Forsman spearheaded an unprecedented project. Purple martin “landlords,” or people who provide housing for the birds, gathered more than 800 fecal samples from across the eastern and central United States. In the lab, Liu has been extracting DNA from those samples to characterize diet across the breeding range.

Barlow Herbst, a rising senior studying biology and environmental science, is using fecal samples to see how the purple martins’ diet changes over the first three weeks after hatching. These birds are aerial insectivores, which means they eat flying bugs, and have seen significant impacts to their food source from pesticides and climate change, Forsman said.

Aichetou Ouattara, a rising senior studying cellular molecular biology and biochemistry, is screening the birds for avian malaria and studying their biomarkers associated with immune activity and tissue damage.

“The project that you start, someone who is coming after you can keep working on it,” Ouattara said. “The data never dies. People can add onto it.”

Purple martins fly away from their nests in the Madelyn Marx Preserve in Kennebunk on July 14. (Gregory Rec/Staff Photographer)<?xml version="1.0"?> Purchase this image MAGICAL AND IMPERILED

The York County Audubon chose the Madelyn Marx Preserve to install the housing because there are similar gourds on a nearby private property, according to the organization.

Local volunteers play a critical role in supporting the species. They help year round, storing the gourds in winter, readying them for spring and regularly recording their observations about the birds throughout the season.

On July 14, they staked out the gourds with their paint rollers. With their assistance, Forsman and her students banded and documented more than a dozen adult purple martins in just a few hours.

“They are very mellow,” volunteer Brad Woodward said. “They’re very wary of us, but they’re not giving any alarm calls. They’re not dive-bombing.”

Marian Zimerman, Kathy Donahue and Brad Woodward, left to right, all with York County Audubon, prepare to capture purple martins in their nests in a marsh in Kennebunk on July 14. (Gregory Rec/Staff Photographer)<?xml version="1.0"?> Purchase this image

That morning, the work was buggy and muggy. Board member Britney Fox brought her two kids — 9-year-old Callum and 13-year-old Ainsley — to participate. Fox, who coordinates the Maine Young Birders Club, said she has been an avid birder for a decade.

“The second you enter this world, this whole universe opens up to you, and shows you how magical it all is and how imperiled it all is,” Fox said. “It’s so cool to be able to go out and appreciate it and know that you’re doing a small part to help.”

Nearby, Forsman helped the 13-year-old release a bird that had been banded. As everyone started to pack up their supplies, the kids chattered about their favorite details about the martins.

“They seem really smart,” the teenager reported back to her mom.

“I like the purplish dark blue,” her brother chimed in.

“It really allows people, my kids, to hands-on see them,” Fox said. “It changes people’s lives to see these things up close.”

A purple martin stands outside its nest in a marsh in Kennebunk on July 14. (Gregory Rec/Staff Photographer)<?xml version="1.0"?> Purchase this image