Nancy Heaslip kneels at the mouth of an entrance to an old graphite mine, waiting for the little brown bats.
She doesn’t have to wait long. They are plentiful tonight, emerging from the mine and fluttering about in the night sky. Occasionally one or two of them flies into a harmless trap positioned about 10 feet from the mine entrance, and Heaslip scoops them up and stuffs them in brown paper lunch bags. The time of capture is written on the bags in black pen.
7:18 . . . 7:30 . . . 7:59 . . .
Heaslip, who is wearing thick gloves and a headlamp, does this for an hour, and then transports the paper bags — about 40 of them — to a nearby work station. There the bats are weighed, their forearms are measured with calipers, and they are photographed prior to being either banded and freed, or euthanized, slipped into vials and stored in a cooler on dry ice. These bats will go to a lab for further scrutiny and testing.
It’s a painstaking process, and the four-member team labors until well after 1 a.m. They are led by Al Hicks, the mammal specialist for the New York State Department of Environmental Conservation’s endangered species program, and they are here to help solve a mystery: Why are the bats dying?
Last winter, tens of thousands of hibernating bats died in caves and mines in eastern and upstate New York, Vermont, Massachusetts and northwestern Connecticut. Many, but not all, of these bats had a white fungus around their muzzles and other parts of their bodies; as a result, biologists named the affliction white-nose syndrome. Some of the bats hibernating in affected areas survived, but not many: In eight New York caves, the mortality rate ranged from 80 percent to 100 percent.
Scientists have many questions about white-nose syndrome, and few answers. They don’t know what it is. They don’t know whether the bats are transmitting it among themselves, or whether people are spreading it, or whether it’s even killing the bats. What they do know is that what’s happening is unprecedented.
“Nothing similar has ever happened,” said Merlin Tuttle, director of Bat Conservation International, based in Austin, Texas, home of the world’s largest urban bat population. “There isn’t even a case, that we know of, of a major die-off of bats associated with disease. We’re looking at a big mystery so far.”
“Any time we start having mass die-offs, we ought to be taking it very seriously as a potential canary in the coal mine,” Tuttle continued. “We may be looking at a serious environmental crisis.” He suggested there are probably multiple causes. One factor, he said, may be population decline in groups of insects that bats rely on for food.
Tuttle doesn’t view the bat die-off as an isolated incident. Recently, scientists have been baffled by the unexplained disappearance of millions of commercial honeybees, a phenomenon known as colony collapse disorder, and a few years ago scientists reported that a strange new fungus that kills frogs, toads and other species of amphibians was spreading around the globe.
Hicks, too, views the bat die-off as symptomatic of an environment in crisis. He suggested that the world’s increasing population and “the increased rate that we move things around on this planet” are taxing the earth. “Our ability to move quickly and frequently around the planet allows ever increasing movement of organisms,” he said. Invasive species such as zebra mussels and purple loosestrife threaten to throw New York’s ecosystem out of whack, he said.
New York is considered the epicenter of the bat die-off.
In winter 2007, the state DEC received a report of unusual bat behavior at a cave outside of Albany. Heaslip, a wildlife biologist, led an expedition to Hailes Cave at Thacher Park, where she discovered hundreds of dead bats. These bats were emaciated and dehydrated, their fat reserves were exhausted and they were dying, or had died, of starvation.
Biologists had hoped the deaths at Hailes Cave were an isolated incident. But today, white-nose syndrome has been found at more than 30 sites in four states: New York, Vermont, Connecticut and Massachusetts. This is a notable increase from 2007, when there were only four affected sites, all in caves located within seven miles of each other in Albany County.
Based on what happened between 2007 and 2008, scientists expect the number of white-nose sites to increase again this winter, said Robyn Niver, an endangered species biologist with the Northeast Region of the U.S. Fish and Wildlife Service. Over the summer, people reported seeing dead and dying little brown bats at their summer roosts in the four states with confirmed cases of white-nose syndrome, and also in New Hampshire and Pennsylvania.
“This is potentially devastating for Northeastern bat species,” Niver said.
Little brown bats, the most numerous bats in the Northeast, are being killed off in the greatest numbers. But the Indiana bat, which is listed as an endangered species, has also suffered, as have northern long-eared and small-footed bats, eastern pipistrelle and other bats using the same caves and mines.
Under darkening skies last week, Hicks and his crew hiked down an old mining road, using GPS to pinpoint the location of the mine entrance. Once they found it, they descended into a gully and began readying for a long night. It was a warm night for late September in the Adirondacks, which was good: When the temperature dips below 50 degrees, bats are disinclined to venture outside.
The trap they set up resembled a metal mattress frame and was strung with thin strings that were light enough to avoid detection, but strong enough to withstand the fluttering of the bats. Normally, the ensnared bats would automatically drop into a large bag at the base of the trap, but Hicks wanted to limit the bats’ contact with each other — “we’re not sure if white-nose is contagious” — and so all of the captured bats are bagged separately, by hand. To convince the bats to fly into the trap, rather than around it, a wall of sticks was erected on both sides of the trap.
At the work station, the team weighed the bats, measured their forearms, spread their wings to look for unusual scarring and holes — evidence of white-nose syndrome — and photographed their wings. The information, which describes the body condition of these bats, is recorded on a chart.
“This is an adult bat,” Hicks said, squinting at the squirming brown ball in his gloved palm. “Ow! I don’t like being bitten. The mass is 8.2 (grams).” He studied the wing. “There’s damage to the wing,” he said. “The membrane is not straight. ... But it looks like it’s healed.” The bat was placed on the table, and its wing was photographed. Another bat also had damaged wings: tiny holes and visible scarring.
Hicks was replicating an earlier study done years ago by Thomas Kunz, the director of the Center for Ecology and Conservation Biology at Boston University. The data his team gathers will be compared to data about bats in other affected sites in the Northeast, to data about bats in control sites in Kentucky and Pennsylvania where no trace of white-nose syndrome has been found, and to the bats in Kunz’s original study. The euthanized bats will be sent to a lab so scientists can learn more about the bats’ body content: the fat levels of the bats going into hibernation — “do they have enough fat?” — and what the composition of that fat is.
Hicks will collect bats once more before hibernation, and then twice while they are hibernating. In the other states where white-nose has been found, biologists are leading similar expeditions. Hicks said it’s unclear whether the white-nose fungus is causing the bats to be sick, or whether it’s a symptom of a sickness afflicting bats with weakened immune systems.
The states where white-nose has been found are also participating in a study of whether hibernating bats are waking up too early in the year, and whether these hibernating bats have enough fat stored to make it through the winter, according to Niver. A routine count of the endangered Indiana bat will be conducted this winter; the U.S. Fish and Wildlife Services expects the census to yield valuable information about how the species is faring post-white-nose syndrome.
Bats are an important part of the ecosystem, and help keep the insect population in check, Tuttle said. “Bats are critically important in keeping insects in balance,” he said.
A bat can eat 50 percent to 75 percent of its body weight in flying insects a night during the summer months.
One of the first cases of white-nose syndrome was observed in 2008, in a non-commercial section of Howe Caverns in Schoharie County by caver Joe Armstrong, who serves as conservation chairman of the Northeastern Cave Conservancy. He had heard about the bat die-off in Albany County, and immediately contacted Hicks. At the time, Armstrong was taking a count of the bat population in Howe’s Cavern; only one bat out of 77, he said, exhibited the tell-tale fungus associated with white-nose syndrome.
Armstrong has continued to document the numbers of bats in area caves. Caves that were home to 1,000 to 1,500 bats in 2005, he said, had only a handful of bats in them last year; a cave where he had once counted 400 hibernating bats only had two.