Climate change could be making birds shrink in size, study finds

CNN | Dec 4, 2019 at 2:00 PM
  • Staggering 600 million birds die every year in the United States after colliding with tall buildings.
  • Larger body sizes help animals in cold places stay warm.
  • Willard began collecting the dead birds after someone casually mentioned they were hitting windows, including at McCormick Place, North America’s largest convention center.