It’s a moonlit August night on Martha’s Vineyard, and deep in the woodlands on the island’s south shore, wildlife biologists Luanne Johnson and Liz Baldwin are setting up a weighing station for northern long-eared bats.
“Martha’s Vineyard and Long Island are among the few places where you can still find a northern long-eared bat,” Johnson said.
That’s because more than 90 percent of these small, insect-eating bats are simply gone—wiped out by a disease called white-nose syndrome that biologists first observed in New York state in 2006, while visiting caves and mines during winter when bats are supposed to be hibernating.
“All of a sudden they were finding bats dead at the entrance, lots of bats," Johnson said. "And then they went inside and they found bats on the ground, and then they found bats covered with this fungus on their faces. It was a very shocking event to see this tragedy.”
Close to six million North American bats are estimated to have been killed by white-nose syndrome over the past eight years. The fungus that causes it may have been brought to this continent from Europe. It’s already been found in 23 states, and there’s no known way to keep it from spreading.
Jon Reichard is the national white-nose-syndrome coordinator for the U.S. Fish and Wildlife Service. Reichard said that, so far, the disease does not seem to have affected bats on Martha’s Vineyard.
“What we learn in Martha's Vineyard is feeding into our better understanding of northern long-eared bats," he said. "There have been anecdotal reports of some areas that appear to be doing better for this species than others, and Martha's Vineyard is one of them.”
That’s where Johnson and Baldwin come in, with their local wildlife monitoring non-profit called Biodiversity Works. They’ve been tracking bats under contract to the Fish and Wildlife Service. Reichard says the results of their work will help the federal government understand what is happening to northern long-eared bats and, maybe, how to help them.
“What we’d like to learn first is, 'Are they really doing better?'" he said. "And if they are, how can that be, what is it about their biology and behavior that is allowing them to do better.”
So Johnson and Baldwin have spent many summer nights in the woods around Martha’s Vineyard, using almost invisible “mist" nets to catch bats as they fly among the trees.
“They fly into the net and it’s very soft and they sort of tumble into a pocket and hang there in the net," Johnson said. "And we check it every 15 minutes. And then when we find a bat, we gently take them out of the net and then we can hold them in our hands, take photographs of them, check their wings for signs of white nose syndrome which is the cause of their decline.”
After the bats have been weighed and measured, they’re released unharmed to continue eating insects. Johnson and Baldwin are comparing their results to those from the island’s first bat study done in the late 1990s, before white nose syndrome began killing off northern long-ears on the mainland.
“The fact that there are still northern long-ears on Martha's Vineyard and Long Island begs the question: 'If they’re here and they’re not showing signs of infection, why is that?'” Johnson said.
The island bats could be hibernating locally, or they may be migrating to caves or mines that are still free of the fungus that causes white-nose syndrome. In any case, the U.S. Fish and Wildlife Service is expected to decide by early April whether or not to list the northern long-eared bat as an endangered species. If that happens, the bats and the places they hibernate will be protected under federal law and there could be additional grant funding for research.