A Beloved Winter Finch Is In Decline—and Scientists Want to Know Why

Feeder visits from Evening Grosbeaks are rarer than in the past, and a new initiative is trying to understand the root causes.
An Evening Grosbeak with a GPS tag on its back, held in someone's hand with a snowy forest behind it.
Scientists tag a male Evening Grosbeak in winter to follow its route to boreal forest breeding grounds. Photo: David Yeany II

One December while home in Pennsylvania for the holidays, ornithologist David Yeany II heard an Evening Grosbeak’s buzzy chirp. Hoping to enliven the yard with the bird’s cheerful chatter and striking hues, he and his dad spent an afternoon building a platform feeder from scrap wood. The next morning, nine oversized finches—nicknamed “grocery beaks” for their insatiable sunflower-seed appetite—were munching away with their impressive namesake bills.

In the past, Northeast birders could expect to spot Evening Grosbeaks every two or three winters. In years when food gets scarce in their breeding grounds in Canada’s boreal forest, grosbeaks will range much farther south in events called irruptions. “Seeing them brings a certain kind of magic to our backyards in the wintertime,” says Matt Young, president and founder of the Finch Research Network (FiRN).

But since 1970, the once common species has sharply declined in the East, making irruptions less frequent and grosbeak visits increasingly rare. Yeany, an avian ecologist in the Pennsylvania Natural Heritage Program at the Western Pennsylvania Conservancy, decided to investigate their disappearance. In 2017 Yeany and collaborators from the Powdermill Nature Reserve banded Evening Grosbeaks in his dad’s backyard, and then later tagged them with tiny radio transmitters, aiming to discover where the birds go in spring. Four years later, the team joined the Road to Recovery Initiative (R2R), an international project to coordinate research and conservation for the most threatened birds in Canada and the United States. Evening Grosbeaks are one of its four pilot species.

Evening Grosbeaks’ unpredictable roving patterns make it vital—and challenging—to understand their movements.

With the program’s support, Yeany, FiRN, and other partners are scaling up their tracking. So far they’ve tagged more than 200 grosbeaks in four states with radio or satellite tags, and they plan to expand across more of the species’ U.S. range. “This is definitely going to be a long-term effort,” Yeany says.

Evening Grosbeaks’ unpredictable roving patterns make it vital—and challenging—to understand their movements, especially because they breed in remote areas. “They’re somewhat secretive, so trying to find where they’re nesting isn’t easy,” Young says. Once a bird is tagged in winter, scientists can follow its journey.

Still, that’s just a piece of the mystery. “Are they going to do that every year? Or will they take different routes?” says Yeany. The data will help answer these questions and could reveal bottlenecks or pressure points for the species and clues about what’s driving the decline.

Researchers have some suspicions. Climate change is stressing  spruce and fir forests where the birds nest, and diseases—such as conjunctivitis, West Nile virus, or salmonella infection—could also be a factor. Another possibility: the timber industry’s efforts to control spruce budworms, a native moth larva that can damage trees. (Grosbeak irruptions often track the insect’s boom-and-bust cycles.) There’s also evidence that grosbeaks are especially vulnerable to window strikes.

Whatever the causes, the degree of the bird’s apparent decline means that even as scientists gather basic data, the team hopes people get involved in conservation now, says Katie Holland, a social scientist with R2R. Treating windows to prevent collisions, keeping cats indoors, and regularly cleaning feeders are good starts. “This is also why it’s a cool species,” says Yeany. “You can literally do something in your yard.”

This story also ran in the Winter 2023 issue as "Keeping Up with the Grosbeaks." To receive our print magazine, become a member by making a donation today.