Climate change leaves northern tree swallows more vulnerable those in the southern US

Tree swallows in the northern U.S. and Canada face the greatest risk from climate change despite responding to temperature the same way as tree swallows in the southern U.S., according to a new study led by Cornell researchers that analyzed nearly 95,000 nests across five decades. The findings, published in Proceedings of the National Academy of Sciences, reveal a critical timing squeeze for tree swallows in the northern half of the United States and Canada, putting them at risk.