White-nose syndrome (WNS) is a devastating disease that has killed millions of bats across North America since it first emerged here around 2006, putting several Canadian species at risk. One of the hardest hit has been little brown bats (Myotis lucifugus), with a 94 percent decline in hibernating populations in Nova Scotia, New Brunswick, Quebec, and Ontario, prompting an emergency assessment by COSEWIC to designate the species (along with Northern myotis and tri-coloured bats) as endangered.
In a recent report in the journal Nature, researchers at the University of Michigan have identified three characteristics—body weight, sleep regulation, and echolocation—that could help little browns survive an outbreak.
WNS—named for the white fuzzy fungal growths seen around the nose, ears, and wings of infected bats—is caused by an invasive fungus, Pseudogymnoascus destructans. The fungus actually eats away at their skin, so infected bats awaken from hibernation to clean it off, consuming valuable energy stores needed to ride out the winter. With their energy supplies tapped out before new insects emerge in the spring, bats have been dying by the thousands. In some locations, entire colonies have been wiped out.
The research team compared the genetic makeup of little browns who had survived an infestation with those who did not. Their findings isolated three traits that helped the bats survive: optimal fat storage, improved sleep regulation, and enhanced echolocation abilities. In other words, bigger bats who are able to sleep longer, and hunt better are more likely to survive. “It is a case of natural selection,” says Giorgia G. Auteri, a PhD candidate at the University of Michigan and lead author of the report.
Auteri says these traits could be used by conservation workers to help prioritize which populations to focus attention on. (With COVID-19 running rampant, bat-related field research and conservation work has been suspended for the time being to avoid introducing the disease, suspected of originating in Asian bats, to North American populations.)
Given the role energy stores play in bats’ survival, Auteri stresses “the importance of good quality habitat for summer feeding.” Cottagers looking to help should leave dead trees standing so they attract insects, avoid the use of pesticides, and consider installing south-facing bat boxes on their property.