Migratory Birds Shrink in Response to Climate Change

                                                                               Field Museum, John Weinstein

Every day new evidence that climate change is driving physiological changes in various animal species emerges. In this comprehensive study, scientist find that birds are responding to a warming climate by getting smaller. 

North American migratory birds have been getting smaller over the past four decades, and their wings have gotten a bit longer. Both changes appear to be responses to a warming climate.

Those are the main findings from a new University of Michigan-led analysis of a dataset of some 70,000 North American migratory birds from 52 species that died when they collided with buildings in Chicago.

Across multiple species and over a fairly short span of time, the changes where easily quantifiable.

"We found almost all of the species were getting smaller," lead author and assistant professor at the University of Michigan's School for Environment and Sustainability Brian Weeks told BBC News. "The species were pretty diverse, but responding in a similar way. The consistency was shocking."

"Periods of rapid warming are followed really closely by periods of decline in body size, and vice versa," Weeks said in the press release.