White-nose Syndrome

Hibernating bats are suffering from a new, mostly fatal syndrome called white-nose syndrome (WNS). WNS is caused by a fungus called Pseudogymnoascus destructans, which was unknown to science until it started killing bats. The fungus can only grow in the same cold damp conditions that bats hibernate in. This fungus grows on the muzzle, ears, wings, and tails of bats while the bats are hibernating. The fungus penetrates the wing membrane, disrupting cells including blood vessels, connecting tissue, and nerves. Bats' wings are not only for flying, but they also help regulate water and gas exchange. The damage to their wings may cause dehydration. Hibernation means that the bats' metabolism is suppressed, including the immune response. Bats must be awake and warm to fight the infection. Bats with WNS wake up from hibernation much more frequently than they normally would and thus use up their stored fat before winter ends. They cannot then survive the entire winter. Some bats, in a desperate attempt to live, fly out of their hibernacula (caves and mines where bats hibernate during winter) in search of food, water and shelter. This means they are flying in the winter, when there is no food and the temperatures are much colder than bats can stand. Many die soon after flying out of the caves and mines, or in the mine itself.

By 2012, over 5.7 million bats in the northeast including Canada had died from WNS. All five cave-hibernating bat species found in New Hampshire are affected by WNS. Little brown bats (state-endangered), previously the most numerous bats in the Northeast, are sustaining the largest number of deaths. The northern long-eared bat has been so decimated by WNS that the US Fish and Wildlife Service listed it as threatened in May 2015. Also dying in New Hampshire are small-footed bats (state-endangered), tricolored bats (state endangered; also called eastern pipistrelles), and big brown bats.

Where Did WNS Come From?

WNS was discovered in the winter of 2006-2007 in four caves in New York. In 2007-2008, WNS spread to caves and mines in New York, Vermont, Massachusetts and Connecticut. New Hampshire has few places for bats to hibernate, so most of our bats hibernate in these other states. In 2008-2009, WNS spread as far as Virginia and up to New Hampshire. Of the seven New Hampshire hibernacula surveyed in 2009, five had WNS. By 2011, the disease had killed most of NH’s hibernating bats, with only 16 found in four of the biggest hibernacula, down from 3230 bats in 2009. Subsequent surveys in NH have found no signs of recovery. WNS continues to spread; the latest map can be found on the USFWS website.

The fungus also grows on bats in Europe, where it is believed to have originated. Those bats do not die from it. Researchers in Europe are trying to figure out why and this may help our bats.

What's Happening in New Hampshire?

Mortality rates at hibernacula in New Hampshire have ranged from 79 to 100% since WNS was first documented in NH during the winter of 2008-09. Mortality in 2011 was devastating. In 4 of the largest surveyed hibernacula in NH, there were 16 bats, with one mine completely empty. In 2009 these same 4 mines housed 3,230 bats. Winter surveys in 2014 and 2015 did not find any signs of recovery. Surveys did not occur in 2016 and 2017 to minimize disturbance to any surviving bats.

A Serious Problem

We don't know what effect losing all these bats might have on our insect populations. Bats eat about half their body weight in insects every night. We don't know whether they are eating significant numbers of pest insects, but we will find out soon if our skies become devoid of bats and full of insects. Over a dozen research labs, many state and federal agencies, and nongovernmental organization partners are currently studying WNS and trying to learn more about what it is, how it is transmitted, and how to prevent it.

The fungus is likely transmitted from bat to bat and between caves and mines by humans. In 2009, the jump from New York to West Virginia and Virginia was a longer distance than bats would be expected to fly. Cavers, however, told us that they explored the affected caves in New York, then went to the other states and explored those caves. The fungus does attach to clothing and gear, and thus can be carried to other caves or mines in any season. There are disinfection protocols for gear that have been developed, and can be found on the USFWS website. However, these protocols are not 100% effective, so if you plan on going to an unaffected state to cave, do NOT take your affected gear. Take only clothing and gear that has never been in a cave or mine in the affected states, nor in a cave or mine in Europe. Also, many caves and mines have been closed to prevent transport of this devastating disease. Observe these closures. And stay out of all caves and mines in winter, as your presence will disturb the bats, causing them to wake up and use more precious stored energy.

Reports of empty barns where bats used to raise babies, empty skies over ponds, and babies being abandoned because the mothers cannot feed them have been coming in to our office and to biologists in other states. You can help by allowing bats to raise babies where they have for years -- in your barn. You can put up a ceiling (even just tacking up a plastic tarp) between your roof and your equipment if you are having problems with the guano in your barn. Bat guano is known as a great fertilizer. Read more information about bats in your house or bat boxes.