New Jersey's little brown bat population has been nearly wiped out by a problematic fungus. But there are signs their numbers may finally be starting to come back.

The white nose fungus, which attacks brown bats and other species of bats during their hibernation, destroyed as much as 98 percent of their population, according to Division of Fish and Wildlife Chief Biologist MacKenzie Hall.

"The first couple of years with white nose here, we had a catastrophic collapse."

She says white nose syndrome is a novel disease to North America that is spread by a fungus that survives in cold, damp environments, like the places where bats hibernate during the winter time.

"Their bodies become very vulnerable to foreign invaders during that time. Their immune systems nearly shut down and their metabolisms are almost entirely inactive. And so this fungus has sort of an easy way to invade into the bats during that time when they are most vulnerable."

But Hall says more recently their numbers have been coming back.

"From at least one very highly-studied site, the Hibernia Mine in New Jersey, we have been partnering with Rutgers to look at the numbers and the recovery of banded bats from year to year.

"And at this point, we are just shy of what their normal rates should be from year to year."

But Hall also cautions that it may take decades for the population to return to normal.

Their overall population has been declining and may continue to decline for the next 20 or 30 years. The little brown bats have an average lifespan of about 30 years.

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