You might say Christine Madliger and Chris Harris are birds of a feather.

Graduate students in Oliver Love’s biology lab, the two have spent their last few summers researching tree swallows on a sprawling national historic site near Cayuga, Ontario.

Located on the Grand River, Ruthven Park includes 1,500 acres of Carolinian forests and open pastures, as well as a mansion and a working farm. Madliger and Harris do their field work there and stay for a couple of months at a time in a rustic little house which they liken to “camping indoors.”

United by their academic passions and their adoration of the idyllic location, the high school sweethearts decided it was the most logical place to tie the knot.

“We were actually married there in 2011,” says Madliger, a PhD candidate who studies a stress hormone found in bird’s blood called corticosterone. Harris, who earned an undergraduate degree in chemical engineering, is working on a master’s degree in biology and studies the same hormone in the bird’s feathers.

All sentimentality aside, the work they do is critically important for understanding whether increased levels of that hormone can be used by conservation biologists as an early warning system to predict disturbances in ecosystems, and the subsequent bird population declines that can result.

“Aerial insectivores and grassland birds are two groups that are declining and that’s raising a lot of alarm bells,” said Madliger. “If there’s some sort of disturbance in the population you might see changes in stress hormones.”

The pair’s field work consists of capturing and banding tree swallows that nest in boxes in the area. They collect blood and feather samples while the birds are on their eggs and again when they’re about 12 days in to feeding their chicks. They also catch insects the birds feed on in order to get a complete picture of available food resources, bird population counts and stress hormone levels.

“You have to put everything into context,” said Madliger. “It’s a complicated hormone.”

Although they haven’t analyzed all the data yet, they believe there are fewer insects, which could account for elevated stress hormones in the birds. Dwindling food resources, however, may not be the only explanation, Harris cautioned.

“The ones raising the most chicks have the highest hormone levels, which makes sense because raising a lot of kids is stressful,” he said.

The migratory birds are known for high site fidelity, but elevated hormone levels may indicate a greater likelihood of not returning to their nests annually. Population counts are normally done by banding and taking physical counts, but Madliger hopes their research will lead to knowing whether fluctuating levels of corticosterone can predict decreases in population levels, as well as improved conservation management policies.

“You don’t want to wait for the population crash,” she said. “Tree swallows are a normally abundant bird and if they’re starting to decline, then you really have to wonder. You need to have healthy, intact ecosystems. Everything is connected in an ecosystem, and as human beings we’re connected too. Everything will start to crumble as you lose certain species.”

View a photo gallery of Christine and Chris at work.