Study: Climate Change Means More Raptors Are Wintering In Idaho

Feb 3, 2014

The American Kestrel was one of six raptors whose winter range is changing. The others are golden eagles, Northern harriers, prairie falcons, red-tailed hawks, and rough-legged hawks.
Credit Neil Paprocki

People in Idaho are seeing more raptors because golden eagles and red-tailed hawks aren't flying as far south for winter. That's according to a new study from Boise State University. The study authors say the change in migration habits means fewer of the birds of prey are being spotted in southern states.

The study used nearly 40-years-worth of data from the National Audubon Society’s annual Christmas Bird Count to track where six types of raptors spent their winters. It found the birds, which in the past migrated south of Idaho, were shortening their trip and wintering in the Gem state.

Study co-author Neil Paprocki recently graduated from the raptor biology master’s program at Boise State University. He saw that more of the birds were wintering at the Morley Nelson Snake River Birds of Prey National Conservation Area near Boise.

Paprocki says the birds are likely shifting their migration patterns north due to climate change. “As the climate warms, there’s new habitat that becomes available to birds that were precluded before because the weather conditions were too harsh and too cold,” says Paprocki.

The rough-legged hawk saw the most dramatic change in migration habits. Since 1975, it has shifted its winter quarters by 185 miles north.
Credit Neil Paprocki

He says other factors may affect the birds, like changes in land use and development practices.

Study co-author Julie Heath is an associate professor in biology at Boise State. She says the raptors are a good indicator that the environment is changing. People may begin to take more notice of what’s happening because birds of prey capture people’s attention.

“People notice when there are more or less of the species they used to see when they were a kid,” says Heath, “or when they go outside and they say 'I’m seeing a lot of eagles this year' or 'I’m not seeing as many as I used to see.' That ties people to their sense of place and how things are changing.”

For example, warmer, dryer winters can be good for the birds, who can hunt better without a lot of snow on the ground. But for people, that can mean low snowpack, empty reservoirs, and less water for irrigation.

Paprocki says studies like this show where, and why, birds are changing their habits. That’s important when it comes to deciding how to manage resources to help birds whose populations are in trouble.

“There’s only a limited number of resources to be able to do that,” says Paprocki. “So we need to be efficient with how we use those resources and be able to figure out the places where they are really needed.”

The study was published last month in the scientific journal PLOS ONE.

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