Birds raise fewer young when spring arrives earlier in a warming world

A new study of North American songbirds finds that birds can't keep up with the earlier arrival of spring caused by climate change. As a result, they're raising fewer young. By the end of the 21st century, climate change will cause springlike weather to begin 25 days earlier, but birds will only breed about seven days earlier. That change could lead to an average reduction of 12% in breeding productivity for songbird species.