BOISE -- Research from Boise State University biologists shows raptors, like golden eagles and red-tailed hawks, are wintering farther north. The theory is warmer winters and lower snowfalls are causing this big change.
The project was part of Neil Paprocki's master's project while he was at BSU. His findings were just published in a scientific journal, PLOS ONE (Public Library of Science), and they could have some interesting implications for our local ecosystem.
Paprocki says the research and analysis shows raptor species are spending their winter months farther and farther north. For example, birds that nest and spend summers in places like Alaska and Canada aren't heading as far south in winter as they used to. In some cases, they're ending up in southwest Idaho in higher and higher numbers.
"We're actually seeing more raptors in the Morley Nelson Birds of Prey Area now than we used to say 20 or 30 years ago. Because raptors that were maybe wintering in Arizona or Nevada, some of them are now wintering in Idaho and around here," Paprocki said.
The biologists looked at six species common in this area: American kestrels, prairie falcons, red-tailed hawks, rough-legged hawks, golden eagles and northern harriers.
"What our study showed is that from 1975 until now, so over the last 36 years or so, we've seen a pretty significant poleward shift in the wintering distributions of these raptors," Paprocki said. "We looked at the six different raptor species, and all of them had shifted their wintering distribution further north, some of them by as many as a couple hundred miles over the last 3 1/2 decades or so."
Paprocki's team believes climate change is the main reason, meaning warmer winters and less snowfall throughout the west.
"That's one of the reasons we think there are more raptors here is that winters are getting warmer and there's less snow so they can find their prey easier, which are things like small mammals like mice or ground squirrels. So when there's not snow on the ground, they can find this prey easier," Paprocki said.
While it may make raptor-spotting more interesting around Idaho, the real question is what this means for the entire ecosystem.
"So there's more raptors here than there used to be, they're eating small birds, they're eating rodents like ground squirrels, rabbits, mice. What's going on with the prey populations if there's more birds here? Are the prey populations eventually going to be decimated because there are so many raptors here? And how's that going to effect the rest of the ecosystem?" Paprocki said.
The researchers did look at other possible reasons for this change, like land use patterns changing with more development in the southwest than the northwest, but the leading guess is climate-driven.
If you'd like to try to catch a glimpse of one of those "winter-ing" birds of prey, Paprocki says this is prime time. He says these types of raptors come out at the Morley Nelson Snake River Birds of Prey National Conservation Area near Kuna in big numbers in late January to mid-February.
Paprocki is currently working in Utah on a proposed wind farm site, doing environmental monitoring of birds and bats which could collide with wind turbines.