Bats have been an unappreciated insect control for many years. Now, last winter and this winter, little brown bats in the Northeastern U.S. have been coming out of hibernation early and dying in the snow.
I have a guess as to the cause. Our autumn season has been consistently longer and finer since 1995. It was especially so that year, but every year since then the oak leaves have hung on long enough to develop bronzy, red, and purplish colours instead of just mud brown. The last two years we’ve had a green Christmas or snow has come just a few days before Christmas. (I’m in Ontario, similar enough to the northeast U.S. and Quebec.)
I think that October, November, and most of December have become too warm for the bats to hibernate but too cold for their insect prey. They are burning energy by staying awake and unable to eat enough to compensate. The result could be starving and early awwakening. It’s just a hypothesis. Can we set up some bat “aviaries” to test it?