Changes to birds’ nesting habits may signal broader climate shift, study says

Global warming may be causing birds to alter their nesting habits, according to a new study that found that some species in Chicago are laying their eggs, on average, nearly a month earlier than usual.

The findings, published Friday in the Journal of Animal Ecology, add to a growing body of research on how birds are affected by shifts in their environment and the potential struggles they may face in coping with climate change.

The research on birds' nesting practices combined extensive collections of eggs preserved in museums with recent observations to compare how egg-laying has changed over time. The scientists studied 72 bird species for which historical and modern data were available in the Chicago area and found that around one-third are nesting and laying eggs an average of 25 days earlier than they were 100 years ago.