A deadly disease for bats is killing fewer of the winged creatures in New England. Scientists are pleased but are not sure why this is happening. No cause or cure is in sight for the fatal White Nose Syndrome, but biologists in Vermont and Massachusetts say the fatality rate has dropped.

More from Vermont Public Radio: Bat Die-Off From White Nose Syndrome Shows A Decline

Tom French is the assistant director of the Massachusetts Division of Fisheries and Wildlife. He says the state is fortunate have a remaining bat population, however small.

“Those bats seem to be bats that can tolerate the fungus; they must have some immunity and we’re hoping the population will build from those bats as the foundation,” French says.

His agency’s main concern now is protecting the surviving bats, in hopes of rebuilding the population. This recovery could take decades because bats have only one baby a year.