Winter weather extremes may kill off bird populations

An American robin (Turdus migratorius) in the snow. Credit: Jeremy Cohen

Some bird species may not be able to cope with increasingly extreme winters — whether that means unusually warm periods or polar vortexes. Researchers examined the impacts of extreme cold and heat on 41 species of birds common to eastern North America in a study published recently in Ecography. They examined community science bird observations submitted to eBird around January 2014, when a four-day long polar vortex occurred, and around a December 2015 winter heatwave. They found that not all species responded the same way to extreme winter weather. During the polar vortex, bird numbers dropped in cold areas, but then returned to normal, suggesting the birds just moved. During the heatwave, birds moved into warm areas and stayed for weeks. They found that warm-adapted, small birds were more sensitive to these extremes in temperature than larger cold-adapted birds. “I was not expecting this impact of the winter heat wave effect,” said Ben Zuckerberg, an ecologist at the University of Wisconsin-Madison involved in the study. “What I found to be most intriguing was the lasting and dramatic response.”

Read more at University of Wisconsin-Madison News.