Caves around the country have been boarded up to protect bat populations against a deadly fungus. Pseudogymnoascus destructans, more commonly known as White Nose Fungus, infects the skin on the muzzle, ears, and wings of hibernating bats, causing them to exhibit strange behavior as they hibernate. It leaves a characteristic, though not always obvious pattern of skin erosion on the affected areas that resembles stringy, white spider webs. Infected bats will wake repeatedly, and move towards the mouth of their hibernacula, or their hibernation zone, and even exit their caves and fly during winter months, eating up their all important fat stores. This leads to dehydrated and emaciated bats, and a nearly 80% decline in many US bat populations. White Nose Fungus, which causes White Nose Syndrome or WNS, has a 90% mortality rate once a population is infected, with effects that may reach far into the future as bat populations are slow to rebuild, as bats can only have one pup per year. The fungus was first discovered in the Northeast, and has spread South and West after its discovery in upstate New York in February of 2006. Since its discovery in the winter of 2007-2008, cases of White Nose Fungus have been discovered in 25 different states - including Arkansas.
Arkansas, and particularly the Ozarks, is home to a karst geography that is particularly conducive to cave formation. The rolling Ozark hills abound with rocky nooks and crannies that once harbored a healthy and vibrant bat population. The fungus has been identified in 14 Arkansas Counties throughout the Ozark and Ouachita mountain regions.
In March of 2010, the Arkansas Game and Fish Commission closed down all caves on public lands in order to prevent the spread of White Nose Fungus. Though WNS’s has the potential to devastate Arkansas’ bat populations, the full extent of its impact is yet unknown.
“So far we have only seen significant decreases in bat populations in a few sites since the fungus was first found in the state in 2012, but we are still going through the early stages of its spread in most of the state and it usually takes a few years for the impact to really start to show”, Said Blake Sasse, a wildlife biologist with the Arkansas Game and Fish Commission who specializes in mammals.
WNS has been diagnosed in seven different Arkansas bat species; Big Brown Bat, Eastern Red Bat, Gray Bat, Indiana Bat, Little Brown Bat, Northern Long-eared bat, Rafinesque’s Big Bat, and the Southeastern Bat. The Indiana bat is a particularly volatile species, and was already considered endangered. Now, authorities are concerned that declines caused by WNS will lead to its extinction.
Laboratory examinations have determined that the fungus requires direct, physical contact to spread, and is primarily spread through bat to bat contact. The fungus can linger in bat guano, persisting in cave sediments long after bats have left the cave, which renders many areas uninhabitable for uninfected populations. Patterns of geographical spread may suggest that humans can harbor the fungus on their clothing and gear, and may also be perpetuating the spread of WNS. Though this mode of transmission has yet to be proven in lab conditions, the New York State Department of Environmental Conservation has been able to isolate fungal spores on equipment and clothing after exiting a contaminated cave.
While WNS has no demonstrated effect on human health, there is much that we humans can do to help slow the spread of WNS. All caves on public land have been closed, and it is recommended that would be spelunkers avoid caves with known bat populations.
“The best thing that people can do to slow the spread is to either not go in caves or if they do, they need to decontaminate their gear and clothing before and after entry” said Sasse.
Many caves, such as Blanchard Springs, are still open, and have rigorous decontamination protocol for visitors to follow. Avoiding contact with bats and their habitats is recommended.
Further research into WNS is needed in order to pinpoint the disease’s origins, and how it travels. The best we Arkansas can do is to be informed, and help prevent the spread of WNS.