A Mysterious Disease Has Nearly Wiped Out Bat Populations in Parts of North America and No One Knows How to Stop It
Jackie Kashmer bundles up against the cold and walks past broken corn stalks and pyramids of freshly cut firewood to the outer reaches of her expansive property along New Jersey’s border with Pennsylvania. There, next to a pigpen, she enters a barn-sized building, kicks off her shoes and heads to the temporary home of her adopted loved ones.
Illustration by Alicia Buelow, www.aliciabuelow.com
This is the New Jersey Bat Sanctuary, Kashmer’s small rehabilitation center with the unenviable task of caring for hundreds of bats suffering from white-nose syndrome (WNS), the disease that has wiped out millions of these flying mammals and pushed some bat species closer to extinction.
The back room, where the ailing bats hang in their upside-down world, is like a miniature hospital ward. The infected ones – little brown bats, one of the species that has been hit the hardest – are frail and almost skeletal. Their wings are blotchy and translucent, like crepe paper stretched too far. Occasionally, Kashmer and her assistant name some of the more memorable cases. Winston was the first WNS patient. He arrived in bad shape and within a few hours had bitten off what remained of his wings. The severely dehydrated animal lost some skin on his bones and was left with ears that looked like they were disintegrating. Winston has since recovered, but his cousins don’t always fare as well.
Kashmer, usually a smiling lady with a penchant for laughing, is serious as she holds one of the sickest bats in her gloved hands, inspecting the animal carefully. The bat’s eyes seem swollen shut and its emaciated body fits all too snugly in her palm. With uncoordinated movements the little guy curls its wings around its body, like a child pulling a blanket closer for warmth.
“If you are not monitoring constantly, you’re going to come in and they’re going to be dead,” says Kashmer, a court reporter by day and a kind of Batwoman by night.
They’re reclusive by day and highly mobile by night. So how do we go about counting bats, let alone assessing how many have died due to a mysterious disease?
It’s not easy, says Carthage College professor Deanne Byrnes, recently named chair of the board of directors of the North American Society for Bat Research. To identify bats in the wild, scientists rely on two primary methods: acoustic monitoring, and trapping and marking. Both suffer from shortcomings that leave serious gaps in information; one is too broad in scope, the other too narrow. In the end, Byrnes said, we have no accurate numbers on how many bats exist in the country. “Our estimates have huge error bars around them.… It’s a problem. It’s a big problem.”
The problem isn’t unique to bats. When it comes to surveying wildlife populations, biologists are often making no more than educated guesses. And the implications of those guesses can be immense, influencing important conservation and development decisions.
The New Jersey Bat Sanctuary is one outpost in a global community of researchers, conservationists, and government officials who are scrambling to understand the deadly epidemic and find some way to counteract it. It’s a community that has been in crisis mode since the disease was first spotted in a cave in New York state in February 2006. Today, at least 11 species of hibernating bats – including four species and subspecies that are listed as endangered – have been impacted by or are at risk from WNS.
In January, the US Fish and Wildlife Service released the most up-to-date mortality figures. Government officials estimate that the disease has killed at least 5.7 million bats. Some biologists say the total might be closer to 7 million dead animals in the last six years.
“It’s probably the fastest decline of wild mammals in recorded history,” says Justin Boyles, a post-doctoral researcher at the University of Tennessee who has been on the forefront of WNS research. “Everything’s gone in some of the northeastern caves.”
The epidemic threatens to permanently disrupt the ecology of the Northeast, where bats play a vital role in keeping insect populations in check. Equally worrisome, biologists have few ideas about stopping the fungus. Even as scientists uncover new information about this mysterious disease, the infection continues its implacable march – and bats, typically a staple silhouette on a midsummer evening, continue to fall, sometimes right out of the sky.
The latest research on WNS, published last October by the US Geological Survey’s National Wildlife Health Center, is simultaneously promising and frustrating. The good news is that the fungus causing the mass deaths has been positively identified – Geomyces destructans, it’s been dubbed, an apt name. It’s clear to biologists that infected bats can spread the disease to healthy cave-dwellers hanging on the wall next to them. “It looks like the most efficient way for it to spread is bat to bat,” says researcher Boyles.
Once infected, the bats develop a white fungus that covers their muzzles, ears, and wings as they hibernate through the winter. They begin acting oddly. Many have been seen flying during the daytime, looking in vain for insects to feed on. Some have been spotted clustering near the entrances of their hibernation sites, an unusual behavior. Then they start to die.
The bad news from the emerging research is that it’s too late to save many bat populations. Certain colonies have been nearly wiped out.
“They may never recover to those pre-white-nose levels,” says Mylea Bayless, conservation programs manager for Bat Conservation International. “The range of mortality at sites is between 50 and 100 percent. Even 50 percent, which is the low end, is really tragic for a long-living, slowly-producing species.”
In Kashmer’s home state of New Jersey, the bat communities have been decimated. Government officials, who have been coordinating scientific information with surrounding states, put leg bands on groups of bats in the fall of 2010 and 2011. Their hope is that in spring, the specimens will still be alive. “In April, before they emerge [from hibernation], we’ll take a look and see what happened,” says Larry Ragonese, press director of the New Jersey Department of Environmental Protection. “Hopefully, we’ll get some understanding of how they are doing.”
Tracking the introduction of white-nose syndrome in the United States has been like cracking a puzzle worthy of Dan Brown. The fungus is believed to be a European native, and any smirks about it originating near Transylvania will likely not produce a smile from bat experts. “Most likely cavers or tourists or someone transferred it from Europe,” Boyles says.
Strangely, though, European bat colonies are not dying of WNS. They appear to be immune to the disease. This could be because of the differing hibernation periods and the fact that European bats are larger than their North American cousins and thus strong enough to withstand WNS. The Old World bats also cluster in smaller groups during the winter months, while in the US some bat colonies have nearly 200,000 animals, a population density that could allow the fungus to spread quicker. Those are just suppositions. The “European Question” continues to frustrate scientists.
“All of the symptoms that we associate with white-nose syndrome here in the US are not happening in Europe,” Bayless says. “There is no mortality. The bats aren’t emaciated.”
Ground zero for WNS is Howes Cave near Albany, New York. From that dark cavern the fungus has spread along the Appalachians and into most nearby colonies. At this point, infected cave-dwellers have been found in 16 US states and four Canadian provinces. Biologists fear what would happen if the disease spread to the South and the Midwest, which have some of the most diverse bat populations in the world.
Beware the Bends
While white-nose syndrome poses a risk to many species of cave-dwelling bats in the Northeast, migratory tree bats across the nation face a different type of threat: wind turbines.
Unlike their hibernating cousins, migratory tree bats – which include the hoary bat, the silver-haired bat, and the eastern red bat – do not inhabit caves. Instead they roost in trees and seasonally travel long distances following warmer weather, much like birds. Over the past several years, migratory bats have been found dead by the hundreds and even the thousands under wind turbines during their peak mating and migrating seasons. According to the US Geological Survey, migratory tree bats comprise approximately three-quarters of the bat fatalities observed at wind turbine sites.
“Bats cannot sustain these impacts without it affecting their ability to recover,” says Ed Arnett, the director of Science and Policy at Bat Conservation International.
Walking into a cave, one can easily tell when WNS has struck, researchers say. Individual bats don’t always show the characteristic white, foamy muzzle, but at the population level the infection is evident. “You’ll see large populations of bats right in the entrance of caves, and that’s where you start seeing them dying,” Boyles says. “The bats, when they die and hit the ground, they sort of turn into this rotten goo.”
Scientists believe the last step before death is starvation, but what’s causing the bats to starve is inconclusive. Boyles believes the fungus makes the bats lose large amounts of water. The dehydrated animals are forced to break from their winter hibernation to quench their thirst. “They use their fat to power those arousal periods, and they end up starving to death,” Boyles says. “In New York, in January, obviously there are not a lot of insects flying around. All the water is frozen. There are reports of them licking the snow.”
Bayless agrees: “If a little brown bat wakes up in the middle of winter, that arousal burns through the same amount of fat that would keep that bat hibernating for an entire month.”
To rebuild the devastated colonies to their former size could take hundreds of years. Little brown bats, for example, produce only one pup a year. In a bad season, they may have none.
To save what’s left of the cave-dwelling bats in New Jersey, Kashmer not only nurses her specimens back to health, she’s also working on creative ways to cure them and release them back to the wild. Right now there’s no agreed upon treatment for WNS. Bat biologists experimented with applying fungicide on the animals, but that just ended up killing them; now researchers are trying to come up with a less toxic anti-fungal agent. Some caves have been quarantined and human access restricted to slow the spread of the syndrome. Kashmer has come up with an unconventional home remedy that she swears by: She soaks the bats’ damaged wings in diluted apple cider vinegar. She says the acidity has helped lessen the ancillary effects of WNS.
A local business has donated a floral cooler, and Kashmer hopes to set up her own hibernation lab, under the guidance of the New Jersey Division of Fish and Wildlife. “If you don’t treat them, they will die,” says Kashmer, who is currently taking care of 60 WNS survivors. “In a couple of years, there are going to be none left.”
Laura Forrest, Kashmer’s assistant, says the dedication is paying off. The team has freed hundreds of banded WNS survivors back into the wild. “They come in on the brink of death,” Forrest says, “and she heals them.”
In another corner of New Jersey, by the outskirts of New York City, bat conservationist Joseph D’Angeli conducts educational programs at schools, libraries, and nature centers on the vital importance of his furry friends. Although they’re seen as an attic nuisance and conjure visions of Bela Lugosi in a cape, bats serve as a vital component in an ecosystem, D’Angeli tells his audience. Nighttime-flying insects are eaten largely by bats. The Center for Biological Diversity says that bats’ insect control saves US farmers billions of dollars a year that they would otherwise spend on pesticides. Bats provide another ecosystem service through fruit and seed dispersal.
Lately, D’Angeli’s seminars have become more like eulogies. “For the first 15 to 16 years, it was talking to people about the importance of bats,” he says. “And now it’s talking to people about white-nose syndrome.”
Although there are few silver linings amid the crisis, D’Angeli believes WNS has been bittersweet. “It’s depressing to hear about it, but it’s also something that may bring the importance of bats again to the forefront,” he says. “You know humans, they always have to be reminded of things when it’s too late.”
One of the biggest challenges to saving bats is convincing the average person to care about an animal that is feared and misunderstood in popular culture. “Most human interaction with bats is when they are pooping in your attic,” Boyles says. “That’s really all people see of them.” D’Angeli agrees: “This planet will be in deep guano if we lose bats.”
At the very least, the epidemic is raising people’s awareness of bats’ important ecological role. The United Nations has named 2011-2012 as the International Year of the Bat, and Bat Conservation International has teamed with Bacardi to broadcast a public service announcement on a billboard in Times Square. But it will take more than that to save these flying mammals. The public will need to become involved, and even if they don’t, drastic changes in a bat-less environment will likely cause them to take notice.
Meanwhile, Boyles will continue his research, heading out to the caves with his infrared cameras and recording equipment. D’Angeli will teach wide-eyed children about the flying mammals they no longer see in the sky. Kashmer, before jumping on the highway for the long commute to her job in Newark, NJ, will travel to her backyard sanctuary, hoping it feels more like a hospital than a hospice. She’ll feed the dozens of sick bats a hearty breakfast of pulverized mealworms and milk substitute, and then let the winged mammals return to their nocturnal slumber, hoping it doesn’t become a permanent sleep.
John Soltes has written for The New York Times, The Hollywood Reporter, and Time.com.