Bat Week 2017

Jason Williams (foreground) and Gabriel Rios-Sotelo are conducting research into the susceptibility of Nevada’s bats to white-nose syndrome. Credit: NDOW

U.S. Fish and Wildlife Service working with partners to protect bats from white-nose syndrome

By Joe Barker
October 24, 2017

White-nose syndrome (WNS) is an emergent disease of hibernating bats that has spread from the northeastern to the central United States at an alarming rate.

Since the winter of 2007-2008, millions of insect-eating bats in 31 states and five Canadian provinces have died from this devastating disease. WNS is caused by a cold-adapted fungus, Pseudogymnoascus destructans (Pd) that infects skin of the muzzle, ears, and wings of hibernating bats. It has rapidly spread as far west as Texas with a jump to the state of Washington discovered in 2016.

Although the bat populations in Nevada and California haven’t been affected by WNS yet, the U.S. Fish and Wildlife Service is working with partners to better monitor and protect bats in those states. In Nevada, researchers at the Nevada Department of Wildlife and the University of Nevada, Reno are focused on preserving the 23 species that play important ecological roles across Nevada’s landscapes.

Jason Williams, a wildlife biologist with NDOW, began swabbing bats in order to test for WNS in 2014. He said NDOW began the long-term collection of temperature and humidity from select mines and caves used by hibernating bats in 2013. They now have data from more than 40 sites around the state showing that Nevada has places where the climate is suitable for Pd growth.

NDOW began the long-term collection of temperature and humidity from select mines and caves used by hibernating bats in 2013. Credit: NDOW

“Our first step was collecting soil and guano (excrement) samples from bat roosts beginning in 2011, but as the national protocol for sampling for Pd/WNS shifted from using soil/guano samples to instead using swabs taken from bats and their environment, we switched to that method in 2014 and have been using it ever since,” said Williams. “This work is necessary because Nevada literally has more abandoned underground hard-rock mines than the remaining 49 U.S. states combined.”

Williams noted that for the past three years, NDOW has gotten funding from the Service’s WNS grants to states program for the Nevada WNS monitoring program. This is the first year that, in addition to funds for monitoring, NDOW and UNR are funded and collaborating together to conduct research investigating the susceptibility of Nevada’s bats to WNS/Pd.

Gabriela Rios-Sotelo, a third year PhD student at UNR, who is focusing her research on Pd and disease impacts, believes that by using predictive modeling and sampling roosts they can best prepare for WNS’s inevitable arrival.

Gabriela Rios-Sotelo, a third year PhD student at UNR, checks on a cave for hibernating bats.  Credit: NDOW

“We are looking at some critical aspects of the host and pathogen physiology, and combining both of those to create what epidemiologists do with environmental niche modeling for diseases,” said Rios-Sotelo. ”We can then pinpoint areas in which bats are going to be most affected here in Nevada, before the disease actually arrives. We are doing this in a way that we don’t have to take or disturb any bats. That’s the really cool part about this I think.”

It is still not known how susceptible bats in Nevada or California will be, but Williams and Rios-Sotelo hope that their research will fill a fundamental gap in understanding. They believe that predicting where the disease will strike next lies in the identifying the ecological factors that allow the fungus to survive and thrive. By combining information on bat immune secretions and Pd growth, Rios-Sotelo and Williams will create an integrative predictive model of WNS/Pd risk areas using ecological niche modeling.

This technique takes into account the conditions that support the fungus (like temperature and humidity) then predicts where those conditions could be found in Nevada.

To understand how WNS affects hibernating bats, Rios-Sotelo said they first need to understand the hibernation process and its effects on the bat’s immune system.

“We are interested in learning what shifts occur in immunity and behavior during bat hibernation in order to learn not only about the immune system of bats, but also to discover how we can conserve bat species from disease in North America before it is too late. As key pest controllers and pollinators across North America the presence of bats will be greatly missed,” she said.

Jason Williams carefully swabs a hibernating bat for Pseudogymnoascus destructans (Pd), the white fungus that causes White-nose syndrome. Credit: NDOW

Current estimates are that bat populations have declined by 80 percent in the northeastern U.S. since the emergence of WNS. This sudden and widespread mortality associated with WNS is unprecedented in hibernating bats, among which disease outbreaks have not been previously documented. Species of bats affected by WNS are unlikely to recover quickly because most are long-lived and have only a single pup per year. Consequently, even in the absence of disease, bat populations do not increase quickly so any recovery from the current losses will take a long time.

So far, WNS/Pd hasn’t been found in any of the test samples or monitored bat populations in Nevada, but both Williams and Rios-Sotelo believe it’s just a matter of time.

“NDOW has been managing our work in bat roosts with the assumption that we’ll find WNS or Pd every winter for the past three winters,” said Williams. “Before the discovery of WNS in the state of Washington, we were unsure if the disease would arrive anytime soon. However, with the discovery of WNS in Washington in the winter of 2015-16, it would be unwise to assume that WNS/Pd isn’t already in or near Nevada.”

Over the last eight years, the Service has issued $7 million in grants to 37 states and the District of Columbia to help combat WNS. This financial support is part of a Service-led, cooperative, international effort involving more than 100 state, federal, tribal, academic and non-profit partners. Funds help states find ways to prevent the spread of WNS while increasing survival rates of afflicted species.

 

Joe Barker is a public affairs specialist at the Reno, Nevada Fish and Wildlife Office.