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White-Nose Syndrome

Since the winter of 2006, White-nose Syndrome has killed more than 5.7 million bats in Eastern North America. White-nose Syndrome (WNS) is a disease caused by a non-native, cold-loving fungus which can be found in the caves of the affected regions. It was first discovered in New York caves during the winter of 2006-2007, initially killing half of the wintering bat population. The name of the disease refers to the white fungal growth found on the noses of infected bats, although it is also found on their wings and tail membrane.

The fungus is currently affecting hibernating bat species in nearly half of the United States and parts of Canada. It continues to spread across the continent. Little brown bats, once a common bat in several areas, are sustaining the largest number of deaths. Caves infected with WNS are displaying 90-100% bat mortality – wiping out most of the cave bat populations. The fungus can persist in cave sediment after bat colonies leave their hibernacula (caves or mines) in the spring, lying in wait to infect next winter’s arrivals. A Department of Environmental Conservation survey shows a 93% decline of little brown bats in 23 caves at the epicenter of WNS. Currently, seven other hibernating bat species are affected by the fungus: little brown bats, northern long-eared bats, big brown bats, tri-colored bats, eastern small-footed bats, the endangered grey bats, and the endangered Indiana bats. The disease is spreading rapidly and has the potential to infect at least half of the bat species found in North America.

What is this fungus and how is it killing the bats? That’s what many bat scientists are asking themselves. We still do not have all of the answers or a cure. The white fungus found on the bats is scientifically called Geomyces destructans (G. destructans). Research has shown that WNS infected bats are awaking from their winter torpor as often as every 3-4 days as opposed to the normal every 10-20 days. This is considered the “itch and scratch” hypothesis, which means the more irritation caused the higher rate of arousal and use of precious body fat. The fungus damages the connective tissues, muscles and skin of the bats while also disrupting their physiological functions. While bats are in winter torpor their immune system is compromised, because the bats bodies are trying to conserve energy by lowing their physiological activity including heart rate, respiration, metabolism, and body temperature. The bats wake up dehydrated and hungry during the cold winters when there are no insects to eat. Unfortunately, about 90% of the bats affected perish due to starvation. The reason why our bats are greatly affected by WNS is because most species of bats only produce one pup (offspring) per year, so their recovery rate is very slow.

The fungus is native to European caves where it evolved with the European bats, allowing the bats to coexist and not be harmed by the fungus. The fungus can be transferred cave to cave from the equipment used in each if it is not properly disinfected. It is hypothesized that this method may have been what brought G. destructans to the United States. The fungus does not only spread from equipment used in multiple caves, it is also transferrable bat to bat. G. destructans is spread by spores, which are released when the bats try to rub the fungus off of their noses and wings. Humans are not susceptible to White-nose Syndrome because the fungus requires a cold body temperature to survive.

The bat conservation community is deeply concerned and involved with fighting the spread of WNS. Researchers are working on finding a way to mitigate this fatal disease. Federal, state and local organizations are focusing on conservation, containment and education.

Environmental Impacts

Bats are the primary predators of night-flying insects. They eat large numbers of moths, beetles, and mosquitoes. Insect-eating bats are crucial to a healthy ecosystem. All bats help play a fundamental role in maintaining an ecological balance. An individual bat can eat a thousand mosquito-sized insects every hour they are feeding, and they usually feed about 3-6 hours every night. By controlling insect populations, bats are critical to forestry, human health, and they also save the agricultural industry billions of dollars each year. Without bats the agricultural industry would be forced to use more pesticides and thus food costs may also increase.

How can you help?

You should not handle bats. If you come across live or dead bats with White-nose Syndrome, contact your state wildlife agency or a nearby U.S Fish and Wildlife Service office. Cavers are asked to continue to observe all cave closures and advisories, and to avoid caves or passages of caves containing large hibernating populations of any bat species. Everyone should follow proper decontamination protocols when visiting caves, mines, or coming in contact with bats.

You can also help the bats survive when they are not hibernating. Plant moth-attracting wildflower gardens to help attract bugs for the bats to eat. Be sure to garden organically without using pesticides. Leave up dead or dying trees to give bats natural shelter. Build or buy a bat house to provide adequate roosting for bats in your area. Contact your elected officials and let them know your concerns about WNS. Teach your friends and family about the importance of bats. Please Buy a Bat House or  Donate Today to help us teach more people about the importance of bats and to involve people in conservation. 

For the most up to date information, please visit the U.S. Fish and Wildlife Service’s page on White-nose Syndrome.

For More Information:

Midwest Bat Working Group
U.S. Fish & Wildlife Service
NASBR: Resolution Concerning the Impacts of White-nose Syndrome
Extinction Spreads like a Fungus Among North America’s Bats
WNS in Europe
Report Unusual Behavior and Deaths in Michigan


2008 Documentation by USFWS biologist
The Battle for Bats: White Nose Syndrome