Bats are 'pigging out' now to combat white nose syndrome

Once a common sight, the spotting of bats zipping through the dusk skies has been rare in recent years since disease decimated bat populations throughout the eastern United States. This fall, though, many have reported to The Daily Sun that they have seen bat activity. A biologist said that although there isn't any hard evidence to suggest a rebounding local population, there is reason to keep an eye out for the small winged mammals at this time of year.

"We don't have adequate data to say yea or nay," Emily Preston, wildlife biologist with N.H. Fish and Game said when asked if the local bat population is recovering. Bats are difficult to study in the wild, she said, because their echo location abilities allow them to avoid nets and other entrapments that are typically used to examine other flighted animals. Preston said local bat populations are usually measured by scientists visiting winter hibernating sites, however, the presence of humans in these caves and mines can disturb the bats, causing them to expend energy when they can least afford to do so.

In fact, that's exactly what the disease that has decimated bats across the eastern United States and Canada, and is spreading westward, does. Known as white nose syndrome, the fungus causes bats to become active during their hibernation, burning through their stored fat and emaciating them before spring comes. Mortality rates are estimated to be about 80 percent, killing millions of bats since first noticed in the winter of 2007-2008.

Recently, though, evidence has shown that there's cause for optimism. Preston noted that researchers in New York state, where the disease was first observed, have concluded that their populations have stabilized after several years of precipitous decline. And, recent research in Pennsylvania has provided a clue as to how surviving bats have adapted. Preston said the study, which bands individual bats and studies them each year, found that bats that were bulking up to 8 grams in preparation for winter hibernation were now packing on enough extra calories to weigh in at 11 grams. "They had individual bats that were quite heavier."

"At this time of year, bats are pigging out — it's likely that they are are eating more than they had in previous years," said Preston. "The other thing that bats are doing this time of year is mating," she said, adding that one interesting characteristic of the bats seen locally is that the females won't conceive until spring.

Come winter, most bats in New Hampshire will fly to Maine or Vermont, where there are much larger hibernating sites, both in abandoned mines and in naturally occurring caves. There are some in New Hampshire, though they are smaller than in neighboring states. Coös County is home the largest hibernaculum, a mine which once held 2,000 bats.