PORTLAND – Biologists are investigating the cause of the deaths of bats as they hibernate across parts of the Northeast, but Maine has escaped the die-off.

The phenomenon has been dubbed white-nose syndrome because afflicted bats have rings of fungus around their noses. Tens of thousands of bats have died from starvation and dehydration over the winter, but it’s unknown whether the cause is a disease or some environmental factor.

One difference between Maine and other states where die-offs have occurred is that Maine lacks lots of caves where bats gather by the thousands for their winter slumber.

Wally Jakubas from the Maine Department of Inland Fisheries and Wildlife says the disease has a better chance of spreading among animals that are packed closely together.