The Mysterious White Nose Syndrome and the 10 Bat Species Most at Risk

White Nose Syndrome in Bats

A mysterious disease called white nose syndrome had already killed more than 1 million bats, and scientists are still searching for clues about what causes it – let alone how to stop it. Since first being discovered in New York in 2006, it has spread rapidly, from cave to cave where bats hibernate. Its presence – marked by a white fungus on the muzzles and wings of affected bats (hence the name) – has since been confirmed in 14 states, as far south as Tennessee, as far west as Oklahoma, and as far north as Canada. It's the first new wildlife disease ever documented in bats.

While the white-nose fungus is the most distinctive sign of illness, fat loss is another, perhaps more telling symptom. The bats affected are often so skinny that they can't complete their winter hibernation without leaving their hibernation caves in below-freezing weather in a last futile attempt to look for food.

So who cares? Bats are just creepy mice with wings, right? Bats act as a natural pesticide and consume huge numbers of insects – as much as their own body weight every night. Because of the loss of so many bats, resurgent pests on some crops – like corn or cucumbers – may prompt farmers to use more insecticide, as the Center for Biological Diversity points out. And because bats are creepy enough that scientists have paid them relatively little attention, no one knows what other problems could result from losing them.

There are 45 species of bats in the United States and Canada, according to the U.S. Geological Survey. Of those, 25 species, including half of those species that eat insects, hibernate in caves and mines and could be susceptible to white nose syndrome; already, at least nine species have been documented with the disease, which can kill off all, or nearly all, bats hibernating in the same cave in a single season. For bats, that's particularly problematic because, unlike most small mammals, they reproduce slowly – females typically give birth to just one pup per year – so steep population declines won't be reversed quickly, if ever.

In this feature, we profile nine bats that have already been affected by white nose syndrome, and one that is at high risk, according to the U.S. Fish and Wildlife Service and other government agencies or independent research organizations. See how surprisingly interesting and grotesquely attractive bats can be – and how unfortunate it would be to lose them.

Indiana Bat - Myotis sodalist

Already an endangered species, the Indiana bat has had its population cut in half – and that was before the onset of white nose syndrome. Unlike most bats, the Indiana bat has brown hair and pink lips. Like many other insect-eating bats, Indiana bats spend winters hibernating in caves, including several in the Northeast that have been decimated by white nose syndrome. Out of all the bats endangered by white nose syndrome, the threat is most immediate to the Indiana bat.

"In winter, the largest hibernating populations of Indiana bats occur in just three states: Kentucky, Missouri, and Indiana, where they form large, highly vulnerable aggregations," according to Bat Conservation International. The disease was confirmed in this part of the country in 2009.

Eastern Small-Footed Bat - Myotis leibii

The smallest bat in the eastern U.S., Eastern small footed bats are not easily found in caves... or anywhere. Already scarce, these bats are being considered for Endangered Species Act protection, not only because of white nose syndrome, but because of habitat loss. They tend to hide behind rocks or under tree bark which makes them difficult to study and track. They can usually be found hibernating in caves in heavily forested areas. Bats affected by white nose syndrome have already been identified in Georgia.

Northern Long-Eared Bat - Myotis septentrionalis

Northern long-eared bats are small, dull-yellow bats found in heavily forested areas. Like most bats affected by white nose syndrome, they emerge at or just after sunset to eat insects. Those big ears? They're a key attribute allowing them to use echolocation – navigation based on the echoes of their own calls off physical items in their path – to catch food.

While long-eared bats are widespread in the Northeast, and little information has been published about specific declines, the U.S Geological Survey reports that northern long-eared bats have been "hit particularly hard" by white nose syndrome, with losses rivaling those of little brown bats and Indiana bats. As of the summer of 2011, they were being considered for protection under the Endangered Species Act, not only because of white nose syndrome, but also because of habitat loss. Unlike Indiana bats, which share many of the same habitats, northern long-eared bats congregate in smaller groups, which could prove to be a saving grace. Time will tell.

Little Brown Bat - Myotis lucifugus

While little brown bats are one of the most common bat species in the United States, even they could become regionally extinct (extirpated) from the Northeast within 20 years, even if the spread of white nose syndrome slows, according to a recent study by Boston University. They're favorite foods are mosquitoes and other insects that develop in water, and because of this they prefer to roost near water. If they do not catch any food, they enter a state similar to hibernation for the day and awaken at night to hunt again. If you don't like mosquitoes (and who does?) then little brown bats are your friends: Each one can eat 1,200 in a single hour.

“These looming extinctions could cause great ecological, economic and cultural disruptions and damage,” said Nina Fascione, executive director of Bat Conservation International. “If one of America’s most common bat species can be dealt a deathblow, at least regionally in such a short time, what will happen to less secure species around the continent?”

Cave Bat - Myotis velifer

Cave bats are voracious eaters, and consume some important crop pests, including weevils, but their tendency to gather in very large colonies makes them susceptible to disease. Just this Spring, the species was newly diagnosed with white nose syndrome; whether cave bats succumb to large population declines or not because of the infection, the development is significant because it is the first "distinctly western" species to be diagnosed with the syndrome, according to Bat Conservation International. Worse still, it shares caves with Mexican free-tailed bats, which are among the most far-ranging species; they could carry the disease far and wide. (Mexican long-tailed bats are the famous bats that emerge from the Congress Street Bridge in Austin, Texas, an endangered vacation.)

"The arrival of the WNS fungus in Oklahoma may open a gateway to the West. It certainly puts all the western states on high alert," said Mylea Bayless, who coordinates response to white nose syndrome for Bat Conservation International. "This may expose a whole new community of bat species to White-nose Syndrome – and we know far less about where these bats hibernate than we do in the east, so tracking and monitoring the disease will be much more difficult."

Big Brown Bat - Eptesicus fuscus

One of the most beneficial animals, big brown bats serve as a natural pesticide on farms across the U.S. Reproductive females can consume their body weight in flies in only one night, and, according to Bat Conservation International, a colony of big brown bats can consume enough cucumber beetles in one summer to prevent the creation of 33 million of their root worm larvae, a major crop pest. However, they hibernate in some of the same caves where white nose syndrome has destroyed colonies, and their robust numbers may be at risk of significant decline.

Tri-Colored Bat - Pipistrellus subflavus

Also known as eastern pipistrelles, tri-colored bats get their name from their fur: each individual hair is tri-colored. They hunt by the water, and hibernate deep in caves. While their diet isn't well documented, they've been known to feed on grain moths emerging from corn cribs, "indicating that they may be of important agricultural benefit," according to Bat Conservation International.

While tri-colored bats are among the most common in the eastern U.S., they are decimated in caves where white nose syndrome has spread, with one wildlife biologist lamenting that a cave where thousands of bats had hibernated just three years earlier "after having WNS for two seasons, had only three bats remaining. One was a big brown, the other two were little browns and both them were covered in fungus. Not a single tri-colored or long-eared bat remains."

Gray Bat - Myotis grisescens

Endangered and at risk from white nose syndrome, gray bats are already beset from all sides. They are known to hibernate in only nine caves each winter, and even some of these caves are at risk from human vandalism and intrusion. And, according to Bat Conservation International, the number of gray bats has decreased by 80% because of pollution in the water they drink.

Big-Eared Bat

On the endangered species list since 1979, two subspecies of big-eared bats – the Virginia and Ozark big eared bats – are at high risk of extinction from white nose syndrome. Together, the two species total under 14,000 individuals, according to the U.S. Fish and Wildlife Service. While the disease hasn't yet been documented in either species, each is vulnerable because it relies on only a small area of habitat (one, the Virginia state bat, in Virginia, West Virginia, Kentucky and North Carolina; the other at the border of Arkansas, Missouri and Oklahoma). When and if the disease reaches the caves where these bats hibernate, the population declines are expected to be swift. In an attempt to protect the species from extinction, the National Zoo took in a colony of 40 Virginia big-eared bats to shield them from disease, but most died in captivity.

Long-lived, with one individual documented at 16 years old, big-eared bats are remarkable for giving birth to pups that weigh nearly one-fourth as much as their mothers. Imagine a human baby born at 40 pounds, and you can appreciate how unusual that feat is. Not surprisingly, those pups are ready to fly within three weeks of birth.

Southeastern Bat - Myotis austroriparius

In May, the latest species to be diagnosed with white nose syndrome was the Southeastern bat, which like other bats of this genus is often referred to buy mixing both its common and scientific names, "southeastern myotis". Even before the onset of disease, the southeastern bat was considered a "species of special concern" – a designation given to creatures that may not yet warrant protection by the Endangered Species Act, but may soon; some populations of southeastern bat have been in steady decline, according to Bat Conservation International.

“The southeastern myotis is the latest, but probably not the last, bat species to be afflicted by white-nose syndrome,” said Mollie Matteson, a conservation advocate with the Center for Biological Diversity, which is advocating for a $5 million high-level federal response to the outbreak. “Already, the disease has hit one-fifth of all bat species in North America, and it is showing absolutely no sign of slowing its deadly pace.”