Hibernating Bats in Peril

by Elaine Carlson – This could be a sci-fi thriller. A deceptively harmless white fuzz appears and begins to grow on the unsuspecting and sleeping victims. In short order, the fuzz disturbs its hosts, causing abnormal and erratic behavior which leads to exposure, starvation, and death. The devastation to the defenseless creatures is nearly complete but the malicious invader is not finished yet as it leaves behind its spore, waiting to attack again.

Unfortunately, this is not science fiction but rather a brief and all too real chronicle of white nose syndrome (WNS) in hibernating bats. Since the discovery of the disease caused by Pseudogymnoascus destructans, a cold-loving fungus, in the winter of 2006-2007 in upstate New York, an estimated 5.7 million bats representing several cave-hibernating species have died. Bat populations in 5 Canadian provinces and at least 25 states in the Northeast and Central US, most recently Wisconsin and Michigan, have been affected (click here for MI press release). These kinds of enormous losses are unprecedented, ecologically significant, and at present, likely unstoppable.

A collaboration of researchers from the US Geological Survey National Wildlife Health Center, the US Fish and Wildlife Service, several states, and non-government entities are contributing much needed knowledge about WNS. Disease transmission is likely from bat to bat and/or cave environment to bat. Humans who visit caves may assist in the movement of the disease on clothing and shoes contaminated with fungal spores. So far, no other mammals besides bats are known to be susceptible. No cure has been found for this disease but any delivery mechanism for a silver bullet intended for wildlife is problematic. Local bat population extinctions are predicted and there is evidence of 80-90% declines in regional bat numbers.

USGS Photo

As dire as this sounds, bat population recovery needs to be in the conversation. It will be time-consuming as bats have a low reproductive rate. While hibernacula are relatively well documented, bat summer habitat and movements are not. The effort will require the difficult discussion about legal protection, particularly for the Northern long-eared bat. (click here for recent Detroit News article). There is a continuing need for public education about bats and to reaffirm the important ecological functions bats perform, such as cave dynamics and the consumption of insects.

A more thorough review of WNS and recent developments in Michigan can be found on the MDNR’s Emerging Diseases website, especially the Michigan WNS Response Plan. The document was prepared in 2010 and while some of the information is dated, it is still valuable.

Please consider attending informational sessions about bats, such as the one to be held at Rockport State Park north of Alpena on June 28, 2014. Lend financial support to bat conservation organizations. Learn about bat habitat; build and install a bat house; save some trees with loose bark in which bats may roost; follow protective protocol when visiting caves. Let decision makers know bats matter to you.

More information may also be found through Bat Conservation International whose mission is to “conserve the world’s bats and their ecosystems to ensure a healthy planet.”

Elaine Carlson is a retired Michigan Department of Natural Resources Wildlife Biologist who remains actively engaged as a conservation program volunteer.