On crisp autumn evenings, Virginia biologist Rick Reynolds conducts a grim research ritual that is quickly becoming the norm for bat researchers in the Chesapeake region. He positions himself at the mouth of caves where bats once swarmed and waits to see what doesn't show up.
"It's almost agonizing to be out on those sites," said Reynolds, who monitors bat populations for the Virginia Department of Game and Inland Fisheries. "A few years ago, we'd be there a few hours and catch at least 40 bats. Some nights, well over 100. Now, we're lucky to get into double digits. It gets painful."
Bat populations are crashing in the wake of a disease called white-nose syndrome, which first appeared in a cave near Albany, NY, in 2006.
White-nose syndrome is caused by a white fungus that is sometimes visible on the muzzles and bodies of infected bats. The fungus lives in caves, where it attaches to bats and weakens them by invading body tissue and disrupting their hibernation cycle.
Bats may be too weak to survive once they leave the cave, or they may become agitated and leave the cave in midwinter for a disoriented flight that usually ends in death.
Bats pick up white-nosed syndrome from each other. People can transport spores between caves on their shoes and clothing but, so far, the disease appears harmless to humans.
The U.S. Fish and Wildlife Service reports that in six short years, at least 5.5 million bats have died in 19 states and 4 Canadian provinces. In the Chesapeake region, this includes Virginia, West Virginia, Maryland, Pennsylvania, New York and Delaware.
Species at research sites have typically declined by more than 90 percent, and the disease continues to spread.
White-nose syndrome has affected a large number of bat species, including the little brown bat, northern and southeastern myotis, gray bat, tri-colored bat (also known as the eastern pipistrelle) and Indiana bat.
The endangered Indiana bat has been called a critical indicator species for the upland part of the Chesapeake watershed. Its population was beginning to stabilize, until white-nose syndrome knocked it back. Federal researchers now estimate that the population has declined more than 10 percent each year between 2006 and 2009.
Pennsylvania has lost approximately 99 percent of its northern long-eared bats, little brown bats, and tri-colored bats since 2008. The state is considering placing them on its endangered species list.
"This infection is not like anything we've seen in mammals to date," said Ann Froschauer of the U.S. Fish and Wildlife Service. "Where we used to have colonies of thousands of bats, biologists are happy to find 50."
Even if white-nose syndrome stopped immediately, the prospects for a rebound are daunting. Bats normally live for 20 to 30 years and most have only one offspring each year.
"It's not expected that bats will rebound to pre-white-nose-syndrome levels in our lives, our kids' lives, or our grandkids' lives. It could take hundreds of years," Froschauer said.
The sudden and dramatic hole in the ecosystem has researchers across the nation scrambling to understand its cause.
The disease has been traced to a European soil fungus (Geomyces destructans) that is new to science. The fungus has no effect on European bats, but when introduced to the United States, it began to act like a pathogen.
"It's a fungus we had no reason to know about," Froschauer said. "It's invasive and behaving in a way that's not expected."
Little is also known about the potential impact of white-nose syndrome on farms and forests.
"Bats are frontline defenders against night-flying insects," said ecologist Dan Feller of the Maryland Department of Natural Resources.
Their diet includes mosquitos, agricultural pests and insects that effect tree health. Without bats, their numbers could conceivably explode.
That could mean problems for organic farmers, who avoid pesticides, and also for traditional farmers, who might need to apply more of them. With the help of stormwater runoff, pesticides on the land also lead to pesticides in the water.
Getting a handle on the scope and financial impact of bat loss is difficult.
One of the first studies, published in Science Magazine in 2011, estimated that 1 million bats consume between 660 and 1,320 metric tons of insects each year. The study also concluded that, nationwide, bats save farmers approximately $22.9 billion each year by helping them avoid or reduce the use of pesticides.
If bats are largely wiped from the skies, that's a bill that might come due.
"And that number is based on increased pesticide use, without also looking at how those pesticides will affect us and the environment," Feller said. "From an ecological perspective, there's a lot more to it."
White-nose syndrome began to hit the Chesapeake region about three years ago. It reached Pennsylvania in 2008.
Greg Turner, an endangered mammals specialist for the Pennsylvania Game Commission, received a call from DeeAnn Reeder of Bucknell University, who first spotted the disease in a Pennsylvania research cave.
Just one year later, most of the state monitoring sites had nearly 100 percent mortality. At a site that once had thousands of bats, researchers found only six remaining. At a similar site, there was just one.
"A third site, after having WNS for two seasons, had only three bats remaining," Turner wrote in a blog for
whitenosesyndrome.org. "One was a big brown, the other two were little browns and both of them were covered in fungus. Not a single tri-colored or long-eared bat remains in those sites." The disease has since invaded every county with known hibernation sites. And those are plentiful in Pennsylvania, which has about 1,500 caves and 5,000 known abandoned mines.
Both Turner and Reeder have been researching ways to attack the disease, but without success so far.
Maryland skies have seen a change too.
Dr. Edward Gates is a wildlife ecologist with the University of Maryland's Center for Environmental Science. On spring and summer nights, Gates cruises mountain roads with a microphone mounted on the roof of his car to record the high frequency sonar calls of bats. He began the work in 2010, when white-nose syndrome first arrived in Maryland.
Gates is now analyzing the silence as much the sounds.
"Over a three-year period, we've had some declines of about 78 percent, which is a tremendous decline," Gates said. "Mostly in the little brown bat and northern myotis."
Feller said that white-nose syndrome is now present in all of the natural caves and mines that are monitored by the Department of Natural Resources, with 90 to nearly 100 percent mortality. Only three abandoned railroad tunnels remain unaffected.
"Until this, our bat numbers were increasing," Feller said. "White-nose syndrome has completely reversed that trend, so quickly that it's hard to deal with."
In Virginia, where mountains along the Shenandoah Valley are riddled with caves, the trend is the same. Reynolds is tracking sites that once had 3,000–6,000 hibernating bats. Today, he finds 50 or 100.
"Last fall at one or two sites, we were actually catching more of the endangered species than the common ones. It was really bizarre for us to see that," Reynolds said.
Reynolds is also surveying summer maternity colonies. While these too have been decimated, Reynolds said the research is critical. "The whole issue is about maintaining populations. If we are going to have survivors, we have to know more about their needs," Reynolds said.
Somewhere among those young bats, and the few survivors that breed them, scientists hope to find answers.
The U.S. Fish and Wildlife Service funds a number of research projects that look at ways to slow the spread of the disease and identify why some bats survive better than others. That includes European bats, which are unaffected by white-nose syndrome, and variations of survivorship here in the United States.
"The thing that makes me most hopeful is the remnant population," Froschauer said. "Are they picking better roosting sites, or doing something else differently? Are they reproducing and are the pups surviving? Hopefully we will get some clues from them that will help interrupt this destructive cycle."
Researchers are also pursuing options for treating white-nose syndrome in the caves, but there are currently few options.
Spraying fungicides or other treatments into the delicate cave ecosystem could damage other organisms, as well as the subterranean network of groundwater that feeds streams and public drinking supplies.
Vaccines or biological controls are more likely, but treating large numbers of bats will be difficult.
"This is novel and challenging, unlike anything we've ever dealt with before," Froschauer said. "But watching the science at work is fascinating and that, in the big picture, makes me hopeful. There are a lot of people who really want to figure this out."
Cavers, don't be in the dark about white-nose syndrome
White-nose syndrome came from Europe to a New York cave in 2006, likely on the sole of someone's shoe.
While the disease has largely jumped from one bat to another, humans can also infect new sites and hinder the survival of uninfected bats.
Advice varies on how tourists and cavers should respond to the crisis, but anyone who cares about cave ecosystems should give extra thought to the situation before going underground.
Some smaller areas are already saturated with the disease, and visits between caves in that limited area won't make it worse. But don't enter caves with hibernating bats, because disturbances during their winter "sleep" decrease their chance of survival.
Visiting different caves in wider geographic areas could definitely add to the problem. If a public cave has decontamination procedures for its visitors, follow them. If not, or if you explore caves on your own, use different shoes and gear at each site.
Read about white-nose syndrome at www.whitenosesyndrome.org to learn more. Both bats and scientists will be grateful you did.
Artificial cave offers safe haven, but will bats use it?
In the battle against white-nose syndrome, a fungal disease that is demolishing bat populations in the United States, creative solutions might make all the difference.
The door on one such project has just opened, and it is hoped that the bats will be arriving soon. It's an artificial bat cave, designed and constructed by The Nature Conservancy in Montgomery County, Tennessee.
"Admittedly, it's way outside the box," said Tennessee chapter spokesman Paul Kingsley.
But it just might work.
The artificial cave won't stop white-nosed syndrome, which has already killed at least 5.5 million bats in the United States and Canada. The fungus is spreading quickly to new caves and will likely survive in the cave soil even after the bats from a particular cave have died off.
Kingsley said the aim is to create an environment where the disease can be slowed, and boost the number of survivors. For now, that's all but impossible in the mines, caves and tunnels where bats spend the winter.
"It's fairly easy to get chemicals that would kill the fungus that causes white-nose syndrome, but those chemicals would also wipe out the cave ecosystem," Kingsley said. "The advantage of an artificial cave is that you can clean it."
The hope is that bats will hibernate in the artificial cave during the late fall and winter. When they leave in the spring, the cave will be empty and ready for decontamination.
Bats still might carry the fungus into the cave, but it typically takes two or three years before the disease wreaks havoc. "Our plan is to keep the fungal load down to first year levels or below and keep it from running rampant," Kingsley said.
The Nature Conservancy spent two years consulting with state and federal experts on both the concept and the design details, including ways to re-create the cool, damp environment of a natural cave.
The artificial cave has been built out of huge pieces of pre-cast concrete and embedded in the hill near an existing hibernation site. Kingsley describes said it as "a bit bigger than a single-wide trailer."
Ultrasonic recordings of bat calls will help lure the bats inside. Humans will not disturb the bats once they are hibernating, but infrared and thermal cameras will record their presence—if they can be persuaded to come inside at all.
"It's a grand experiment," Kingsley said. "If the worst happens and the bats won't take to it, it can still be used as a research facility."
The cave cost approximately $300,000 to design and build. "We needed to build it fairly quickly and without too much expense because the idea is, if it works, it could be duplicated across the country," Kingsley said.