White-nose Syndrome and monitoring
A Little Brown Bat with White-nose Syndrome.
Photo by Ryan Von Linden
bats in Delaware for the deadly disease
In April of this year, Division of Fish and Wildlife biologists detected the fungus associated with White-nose Syndrome (WNS) on two Delaware bats. WNS is a disease that has caused mass mortality of bats at hibernation sites in 12 states and two Canadian provinces. WNS is a disease that has killed more than 1 million bats so far, most of them in states with caves and mines that bats colonize when hibernating.
Has WNS been found in Delaware?
In Delaware, the fungus, Geomyces destructans, was found on bats that had recently arrived at their summer roost sites. Once the bats leave their caves, they typically groom the external fungus off their fur, but part of the fungus can persist in the bats’ tissue for longer periods of time. Since the fungus does best and only appears to grow in cold, damp places like caves, it’s not likely to survive the hot Delaware summer. However, very little is known about summer persistence of the fungus and its life cycle is still being investigated.
Why would WNS be a problem in Delaware?
Although Delaware’s biologists knew the state’s cave-hibernating bats had to come from WNS-affected caves, the confirmation of the fungus on bats here was very concerning. The impacts of WNS are likely to be far reaching and, even if WNS-affected bats survive the trek to Delaware, they may not have as much energy to spend on bearing and raising young. Plus, we would expect fewer and fewer to survive and make it to their maternity sites in Delaware at all. It is unclear how many Big Brown Bats overwinter in Delaware and if they are impacted by WNS.
Which bats are affected by WNS?
“Right now, we are looking for any bats overwintering here in Delaware. The most likely bat species for people to see in winter is the hearty Big Brown Bat, which can overwinter in people’s attics, basements or barns. We also plan to check bats for signs of WNS as they return to their summer nesting sites and to continue our volunteer bat count program in the spring,” says DNREC Wildlife Biologist Holly Niederriter.
Only bat species that overwinter communally are known to be affected by WNS, but those include some of the more common bats, such as the little brown bat, big brown bat and the tri-colored bat (formerly known as the eastern pipistrelle). Northern long-eared bats,small-footed bats and the federally endangered Indiana bat have also been affected. WNS was first discovered in 2006 near Albany, N.Y.
What causes WNS?
The cause of the disease and mode of transmission are still under investigation but the disease can be spread from bat to bat, through the air and it exists in the substrate (soils/rocks/sand) of affected hibernation sites. The namesake white fungus found on bats’ noses (as well as their wings, ears and tail) could be the cause, but not all affected bats have the fungus, which itself may travel on spores for hundreds of miles with bat migrations. WNS could also be triggered by some kind of intrusion that thwarts the bats’ immune system and hinders their ability to fight off the fungus or other pathogens.
Is WNS a problem for humans?
There have been no reported human illnesses attributed to WNS, but research continues across a wide spectrum of science, medicine and academia to discern if there is any risk to humans in contact with affected bats.
Other (non-WNS) Threats to Bats
Loss of habitat; wind energy (bats killed by turbine blades), flyways, cave visitation that disturbs their routines and depletes their energy reserves during hibernation, direct vandalism, environmental contamination, loss of water supplies (in the west).
White-nose Syndrome Fact Sheet
US Fish and Wildlife Service WNS Page
WNS in Pennsylvania
| Little Brown Bats affected by White-nose Syndrome. Photo by Nancy Heaslip, USFWS|