Shifting Habitats: Bird Migration And Climate Change

May 26, 2020

Summer tanager pair, male (red) and female (yellow) – an example of a neotropical migratory species of bird that fly south to the Caribbean or Central America to spend the winter, according to Dr. Clark Rushing of USU Department of Wildlands Research and the Ecology Center.
Credit Frank Retes, Southern Arizona

The North American Breeding Bird Survey, a large-scale citizen science project started in 1966, is the basis of a newly-released study on migratory bird habitats and climate change. 

“Can we look at the rate of changes and understand why some species might be shifting their distributions in response to climate change and why some might not?" Clark Rushing said.

Rushing is an assistant professor of population ecology in the Department of Wildland Resources and Ecology Center at Utah State University. He and colleagues at the U.S. Geological Survey noted bird populations declining over the past half century in the North American Breeding Bird Survey.

Whether significant warming trends during the same time played a role in the diverging trends of the decline rates was not known. So, they constructed a study of 32 bird species, controlling size and geographic distribution, with different migration behaviors to investigate.

“We sort of had this prediction that temperatures are warming.That's newly creating areas that species might be able to inhabit that they were previously not able to further north,” Rushing said. “The trait that really came out as the most important was whether species spend the entire year in North America, or whether they're migratory species that winter down in the tropics.”

Rushing said the neotropical migrants, those wintering south of the equator, showed the most rapid decline compared to birds that either were resident or that migrated south within North America. He said this suggests there is something other than just the flight distance keeping this group of birds from being able to use the more northerly habitats effectively – and that is what he and his colleagues hope to investigate next.

Instead of being discouraged about declining bird populations, though, Rushing is focused on positive actions that people can do to make a difference. Drinking “bird-friendly” coffee locally, he said is a great start. Or joining in a citizen science project, like eBird, run by Cornell Lab, could be an easy, fun activity.

“It's an app you can put on your phone. It'll generate a list of birds that you're likely to see in that area,” noted Rushing. “And then you can just check them off as you go up.Then send it straight to this database that I use. eBird data is part of my own research.”

More about bird-related citizen science projects eBird can be found here, the North American Breeding Bird Survey here, or other projects to bring birds back here.