Bats on the rocks: new habitat may provide refuge from white-nose syndrome

Today’s post is from writer Gretchen Newberry, a Ph.D. candidate at the University of South Dakota Biology Department. Gretchen studies habitat, nest success and heat stress of the Common Nighthawk. This month, she is switching from birds to bats — the vital role they play in nature and efforts to respond to white-nose syndrome, a deadly fungal disease that has killed more than six million bats in North America during the past decade.

In March every year, a colony of bats has been emerging from a honeycomb of cracks within the talus slopes in Maine, a newly discovered habitat. These rock piles anchor the base of cliffs in coastal and western areas of the state and are composed of stones that range from golf ball-sized to boulders Maine Department of Inland Fisheries and Wildlife biologist Cory Mosby describes as “Volkswagen-sized.” Researchers in Maine are on a quest to learn more about the bat species that use these non-traditional habitats, their home ranges, and the prevalence of white-nose syndrome (WNS) in this talus habitat.

Accessibility to these sites is an issue. Crevices are too small for a person to climb into, so white-nose syndrome (WNS) researchers must wait for warm winter days or the end of winter for bats to appear. And while the westward- marching leading edge of the disease is in faraway states like Nebraska, Texas or Washington, researchers in Maine, where WNS has been established for nearly a decade, still have much to learn about non-traditional habitats, the bats that use them, and their significance for management of the deadly disease of hibernating bats.

Talus slope in western Maine. Credit: Cory Mosby, Maine Dept. of Inland Fisheries and Wildlife.

Places like Acadia National Park are on the frontier of research in the Northeast because coastal talus slopes are off the beaten path. While large cave and mine sites that have experienced large die-offs associated with the WNS fungus, Pseudogymnoscaus destructans or Pd, are relatively well-studied, biologists have only begun to account for other habitat types in the region.

This winter Mosby will explore Acadia National Park’s talus slopes with the help of many years of research by park biologists. For the past two winters, Mosby explains, park researchers like Bruce Connery have radio-tagged bats at their hibernation sites to describe their home ranges. While Acadia National park is on an island connected to the mainland by a bridge, bats often cross the waters and range 8-10 miles inland.

With a team of researchers that includes Connery, Erik Blomberg of University of Maine – Orono, and David Yates of the Biodiversity Research Institute, Mosby hopes to shed light on where Maine’s bats give birth and hibernate.

In Acadia National Park alone, Mosby’s team will survey 5 acres of rock, a labor- and time-intensive endeavor as an infrared camera can only detects bats within a narrow field of vision.

Recording bat calls with detectors will be crucial as they will monitor approximately 30 talus slopes November to March across the state, focusing on mainland mid-coast and White Mountain regions.

When bats emerge, the team will catch them with large, fine “mist” nets and identify the species, which could include northern long-eared bats, eastern small-footed bats, and little brown bats. They will swab the bats for Pd and assess wing wear associated with the fungus. The researchers will assign each bat a wing score because deteriorating skin, holes in the thin skin between their digits, and scars are an index of body condition and a predictor of the bat’s ability to shed the fungus in warmer months.

If the research is successful, information about this newly discovered habitat will yield important information about WNS, because bats typically pick up Pd in winter and slough off the fungus in warmer months. These smaller crevices might hold smaller colonies and provide a refuge for the state’s bat population while larger colonies in caves and mines might be facing greater exposure to the fungus.

A brown bat with white-nose syndrome. Credit: USFWS

This research and a project in Nebraska also looking at non-traditional bat roosting sites are two of 13 research projects funded by the U.S. Fish and Wildlife Service in 2017 in a $1.5 million effort to investigate issues related directly to management of WNS . When asked how his work differs from projects in the west, Mosby replies “Maine is not unique.” Everywhere, there is large difference in numbers between the bats the researchers see emerge into the night sky and those that fall into their mist nets. Like everyone else, he adds, “We just want to want to know: Where do the bats go?”

For more information and to find your local contact, visit whitenosesyndrome.org.