Between the densely forested banks of the Musconetcong River, a lone brown bat fluttered and tilted through a light drizzle to scoop up the newly hatched mayflies hovering over the dark water as it flowed through Stephen’s State Park.
It is a scene quickly disappearing from New Jersey — and the rest of the Northeast.
Extinction is a possibility for North American bats, biologists said last week as they continued to battle the enigmatic “white-nose syndrome” that has killed more than 1 million of the winged mammals since 2007 in nine states from Vermont to Virginia.
Bats help nature maintain an ecological balance and assist agriculture by feeding on insects. They also devour the pests that tend to bug people cooking or camping out in the summer months. Biologists contend a bat population of 100,000 eats upward of 21 tons of insects from spring to fall.
Last month, scientists entered the Hibernia mine in Rockaway Township, one of the region’s largest bat “hibernaculum” or hibernating locations, to check on the bats before they normally fly out to summer roosting areas.
“We counted only 750 bats. … We normally find between 26,000 and 29,000 bats in our counts there at the same time each year,” said Mick Valent, a zoologist with the state Division of Fish and Wildlife.
It is unclear whether the missing bats, 95 percent of the population, are dead. But that has been the trend in other states since New York biologist Alan Hicks discovered the syndrome in 2006.
“White-nose syndrome” was discovered in New Jersey in January when Valent found hundreds of dead bats in the Hibernia mine. Other bats displayed classic traits of the syndrome — prematurely leaving hibernation and frantically taking to the skies in search of insects that had not yet hatched. With their fat reserves exhausted and food unavailable, the bats froze and died.
Valent said there is a chance that some of the Hibernia mine bats survived and left the mine days before he got there.
“Some states had found bats in the areas of their summer roosts two to three weeks earlier than normal,” Valent said. “I do know we had a high mortality. But we’ll have a better sense of mortality in the fall when we see how many survived the summer and return to the hibernaculum.”
Yet white-nose syndrome — so-named because of a strange white fungus that appears on the noses and wings of affected bats –stresses bats even after they emerge from hibernation. Scientists are finding the wing membranes damaged on many bats and they fear the females may not be able to reproduce.
“We’ve found scar tissue and actual decomposition on the wings. If they can’t navigate properly in flight, they can’t feed and they can’t reproduce,” said Professor Thomas Kuhns, director of the Center for Ecology and Conservation Biology at Boston University.
The nine species of bats found in New Jersey, for example, mate in the fall before entering the hibernaculum, but suspend fertilization throughout hibernation and until they re-emerge in the spring. If the female bat has enough fat reserves, it will ovulate, become pregnant and give birth to one pup in summer.
“We predict some of them will not have enough fat to ovulate and ones with damaged wings will not get enough food to produce milk for the pups,” said Kuhns, who will lead a research team this summer to observe female bat roosting sites known as “maternity colonies” in old barns and trees.
Other biologists from several states, private organizations and government agencies may be close to determining a cause, how it spreads, and how to stop a potential wildfire-run across the nation. The fear is that white-nose syndrome will move to North America’s largest bat colonies in the South and Southwest.
“We have a strong circumstantial case for the fungus,” said microbiologist David Blehert at the National Health Center of the United States Geological Survey in Wisconsin, noting that until now, scientists were unsure whether the fungus was a symptom, side effect or the actual culprit.
“We have a paper coming out in the next two weeks, which … describes the fungus as a new species and names it. The best data we have to date is, that it is associated with and causes severe skin infections with the bats we studied,” he added.
Yet the bat deaths may still be part of a more complex relationship between the fungus and other factors, said Kuhns of Boston University, noting studies have found hibernating bats lack necessary unsaturated fats — an important ingredient for survival and reproduction.
“It seems likely if the animals are not coming out in good condition from hibernation, the chances of raising young is not going to be successful. I think were are facing a double whammy,” said Hicks, the New York biologist.