White-nose Syndrome: A new threat to New Hampshire's bats
What is 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 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. WNS seems to have the biggest impact on the little brown bat, which is common in New Hampshire. It also is devastating the northern long-eared bats.
The US Fish and Wildlife Service listed northern long-eared bats as Threatened in May 2015, since the population of these bats has declined so precipitously in every state where WNS has taken hold. The Eastern small-footed bat (state endangered in NH) has also been affected, as have all cave-hibernating bat species: big brown bats and tricolored bats (also called pipistrelles). Three federally listed species are threatened by WNS, the Indiana bat, which has been killed by WNS, the gray bat, which has been found with the fungus, but no significant mortality has occurred, and the Virginia big-eared bat which has not been affected despite having WNS in hibernacula that they use. The fungus has also been found on three other species of bats, but none had signs of WNS.
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. In 2010, WNS spread to west into Missouri, south to Tennessee, and north to Ontario and Quebec, Canada, as well as to additional counties in already affected states. The disease has continued to spread, now affecting 26 states and five Canadian provinces. This devastation of 6 species of bats is unprecedented.
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?
Bats in New Hampshire use mines or talus caves to hibernate, but there are few places humid enough for them. Most of our caves bats fly to Vermont, Massachusetts or New York to hibernate. In 2009, bat populations in all surveyed mines were higher than in the past two years. It is possible that some bats chose not to fly to those other states to hibernate due to white-nose syndrome.
Unfortunately, that trend did not continue into 2010. At the second largest hibernacula, the population in 2009 was 982 bats of three species. In 2010 that mine had just 281 bats of only two species, the northern long-eared bats were gone. That is an 83% decline! Overall, the population dropped 70%. In 2011 things were even worse. The second largest hibernacula had only 2 bats. In all surveys, only 30 live bats were found, with one mine being empty. The largest hibernacula was not surveyed, but we got several calls from nearby homeowners that bats were flying in February, all destined to die. The total population decline in NH is nearing 99%.
One bit of good news came from two hibernacula that were discovered in 2010. They are in old military bunkers, and there was no sign of WNS. This population, although small, may offer some additional hope. In 2011 the population had doubled, to 114 bats. However, swab samples taken from those bats did show that some of them had the fungus on their bodies. They all appeared in good health in March, and not emaciated. Biologists from NHFG and US Fish and Wildlife Service monitored both the bats and the temperature and humidity in the bunkers, using data loggers placed in several rooms in each bunker. Several bats were banded with unique number bands to see if they would return in 2012. Bats showed visible fungus in 2012 but two banded bats that had the fungus in 2011 returned and looked healthy. Unfortunately, in 2013 all the bats except the big brown bats were gone. There were 62 big brown bats in January 2014, with 7 of them being banded.
The discovery of bats using bunkers in NH had led biologists in several other states to look at their bunkers in hopes that controlling temperature and humidity might allow the bats to survive the winter free of WNS. One bunker seemed to have proper conditions, and bats were transplanted there from sites in NY and VT. They survived fairly well over the winter, and this experiment continues. The hope is that these bunkers can be used to learn more about methods to control the fungus.
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 as 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 terrible 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.
WNS now appears to be affecting bats during the summer months. Reports of empty barns where bats used to raise babies, empty skies over ponds, and babies being abandoned as 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.
What You Can Do
- If you have bats roosting in your barn or shed and can leave them there so they can breed. Read more information on solving any issues you might be having in your barn.
- Participate in the statewide summer colony survey. If you would allow a researcher to come study the bats in your barn or shed, please contact the Wildlife Division at firstname.lastname@example.org.
- If you find dead bats, particularly in a summer colony or several dead bats in the same place in the winter, report it online. If you can’t report it online, call the Wildlife Division at (603) 271-2461, or email us at email@example.com. We may want to collect specimens to send to researchers who are studying this disease. Please note: due to the volume of reports we are not able to call or email everyone back. We will call or email if we want to get specimens or need additional information. There is nothing we can do for these bats, unfortunately. DO NOT HANDLE ANY BAT, DEAD OR ALIVE, WITHOUT THICK GLOVES.
- Stay out of caves and mines in any state from Maine to Missouri and in eastern Canada, and observe cave closings in other states. Follow the USFWS advisories and decontamination protocols found at whitenosesyndrome.org/resources/cavers.
- CBS News Video (July 2011): Dying Bats Called No. 1 Mammal Crisis in U.S.
- Download a Fact Sheet about White-nose Syndrome in NH
- The Nature Conservancy (Article) Bananas to Bats: The Science Behind the First Bats Successfully Treated for White-Nose Syndrome, by Matt Miller
- WNS - latest from the US Fish and Wildlife Service
- WNS - latest from the US Geological Survey
For more information on bats in New Hampshire, contact the Wildlife Division at firstname.lastname@example.org