"Eastern imperial eagles are hard to catch, and individuals are difficult to tell apart," Rudnick said. "By performing genetic analysis on feathers collected at the site, we were able to track the presence or absence of individual birds over a six-year period."
This kind of monitoring is essential to conserving rare or endangered species, said Todd Katzner, director of conservation and field research at the National Aviary in Pittsburgh and a study co-author.
"You can't conserve a population unless you know how big it is and whether it's growing or shrinking," Katzner said. "This approach allows us to monitor wild populations in a way that's less invasive and more cost-effective than other methods."
Observational studies of imperial eagles suggest these birds, like most large birds of prey, are at least socially monogamous. This means a male-female pair stays together throughout the breeding season and shares responsibility in raising young, DeWoody said.
But just because two individuals act like a pair doesn't guarantee they're not having trysts on the sly. In fact, studies over the last decade have shown most broods of socially monogamous birds include offspring from at least two genetic fathers.
"Our study actually stands out as a relatively rare instance in which DNA fingerprinting uncovers genetic monogamy in a bird population," DeWoody said.
Unlike their smaller songbird cousins, most raptors are believed to be truly monogamous, and this study provides the first genetic confirmation of monogamy in at least one species, DeWoody said.
"It's very likely that other raptor biologists will follow this with similar studies on other species of interest like bald eagles," he said.
This project is one part of a larger research p