Just above the Missouri River waters in Nebraska, perch limestone slopes that hold newly discovered hibernation sites for bats. There is little topography that rises above the horizon in the heart of the Western Corn Belt, but the river cut deep banks on the Nebraska side and left ribbons of limestone cracks that may hold the secret of bats in the Northern Plains.
This subtle landscape holds clues to the westward spread of the White-Nose Syndrome (WNS) fungus, Pseudogymnoscus destructans or Pd. The fungus has decimated bat populations in the regions of the U.S and Canada, and where bats hibernate may help unlock the mystery of why Pd is spreading west.
"We are finding out where bats are, and where the fungus is," says Dr. Jeremy White of University of Nebraska Omaha.
White is part of a group of bat researchers in Nebraska that has been monitoring caves and mines throughout the state for many years. This group includes retired University of Nebraska Lincoln faculty Dr. Trish Freeman and Dr. Cliff Lemen, and Mike Fritz of Nebraska Game and Parks. In the past couple years, they found Pd on swabbed bats in mines and caves in southeastern Nebraska. In the winter of 2016-2017, they found the fungus on bats emerging from hillside cracks above the westward-ranging Missouri River. The state is at the leading edge of the disease as it spreads westward.
These cracks are considered non-traditional hibernation areas because they don’t conform to typical notions of bat wintering grounds. Much of WNS research has been conducted in large caves and mines where massive die-offs have been recorded, especially in the northeastern U.S. In the Great Plains region where caves, cliffs, and mines are scarce, researchers have started looking for slopes that hold smaller slices in the earth that might attract bats.
There is much that is unknown about winter distribution for many bat species, including if and where affected bat species migrate, White says. So, describing a species’ range is critical to knowing where bats hibernate.
In Nebraska, researchers expect to find little brown bats, tricolored bats, and federally threatened northern long-eared bats. Big brown bats are also susceptible to WNS, but are generally more resistant, possibly because of their tendency to hibernate in homes and attics.
With the help of a U. S. Fish and Wildlife Service (USFWS) grant administered through the Nebraska Game and Parks Commission, scientists plan to return this winter to the Missouri River cliffs and other sites where bats were found hibernating. White and his team of researchers will use acoustic bat detectors along cliffs and infrared cameras provided by Nebraska Department of Transportation to identify cracks where some bats briefly emerge on warmer winter days. Researchers will then return when hibernation season ends in March to string long, fine nets over the cracks to catch bats. The researchers will identify bats by species, swab them for the Pd fungus, and assess fungus-associated wing damage. Eventually the research might expand up the Missouri River as the team explores more limestone cracks.
In some ways, White added, the rarity of cliffs, mines and caves in the Northern Great Plains allows researchers like himself to focus their efforts within the state. However, because much is unknown, they must survey any site they can find. Moreover, the scarcity of such sites stirs up a series of questions that drive his research. What is the ideal structure of a limestone crack for bats to hibernate? Which species use the cracks? Is hibernating in cracks an uncommon strategy? How many bats are in a single crack? Without being able to walk into a crack like cave researchers might, methods for detection will have to be worked out in coming years.
The difficulty in finding bats in this landscape with few cliffs, mines and caves has also hampered disease detection. Researchers know that bats are in the area, but not where they winter. Cavers, climbers and other members of the public have provided useful information for researchers in other regions where they have found dead bats in hibernation areas. While the Northern Great Plains doesn’t support a large climbing community, the public can still help Service biologists and researchers like White identify winter and summer habitats as well as report dead bats.
In the meantime, researchers in the Service are taking a hard look at where bats might be and reviewing the methods White and other researchers are using. These include monthly collaborations between the Service and bat researchers in Colorado, Kansas, Nebraska, Montana, South Dakota, North Dakota, Utah, and Wyoming, including staff at Devils Tower National Monument and the Black Hills National Forest. As the leading edge of WNS expands westward, the team is committed to unlocking mysteries of where bats hibernate in the mountains and prairies.
Researchers might still have time to work on their methods and explore more potential habitat to help curb the spread of WNS over the western U.S. As White points out, the one central Nebraska site his team tested was negative for the Pd fungus -- and that’s good news.