Author Ann Froschauer is the Pacific Northwest Region's White-nose Syndrome Coordinator for the U.S. Fish and Wildlife Service
When white-nose syndrome was confirmed in Washington State earlier this year, a collective shudder went through the white-nose syndrome and bat research community.
Since the discovery of white-nose syndrome (WNS) in New York about a decade ago, scientists have learned a great deal more about bats, the disease, and the fungus that attacks them during hibernation. As WNS continues to spread and affect bat populations across the eastern U.S. and Canada, we race against the clock to learn more about the disease and look for ways to intervene and save our bats before it’s too late.
We’ve made amazing progress in a relatively short period of time. We have identified the pathogen and have refined our ability to detect it even before bats start getting sick. We have learned about how the disease affects individual bats and its effect on bat populations. We have learned more about how the disease spreads. We’ve been studying bats that have survived in places the disease has been for a long time, and we’re exploring ways to help bats survive where the disease is just getting a foothold. While we haven’t discovered a “silver bullet”, we have made great strides in the science that guides our understanding, which will ultimately help us conserve bats across North America.
So when the disease was discovered in King County in Washington in March, it threw a wrench in the works . . . there are lots of questions about the discovery and about western bats, and not a lot of easy answers.
One of the biggest hurdles we faced after the infected little brown bat was found was where to look for others. There wasn’t a known hibernation site in the area; in fact, there aren’t many hibernation sites for bats known in Washington state at all. We know some sites where Townsend’s big-eared bats hibernate, but we don’t have much information on other places where little brown bats or other species spend their winters.
Most WNS detection techniques target Pseudogymnoascus destructans (Pd), the fungus that causes WNS. Back east that means going to sites with hibernating bats and taking samples from affected bats or the environment: usually caves and mines. In the absence of known hibernacula in Washington state, we face a dilemma. How do we look for Pd and WNS when we don’t know where to start? How do we detect Pd and WNS with the tools we have in places we don’t know about?
Washington Department of Fish and Wildlife (WDFW) quickly jumped in and used a few other techniques to look for signs of the disease. To provide clues as to places where WNS might be affecting bats, they put out acoustic detectors to look for increased or irregular bat activity near where the infected little brown bat was found.
They also contacted the state rabies lab to see if they could get some of the bats that had been submitted to that lab and test them for WNS, working with the USGS National Wildlife Health Center (NWHC). One of these bats, a silver-haired bat also collected in King County in March, tested positive for Pd. This information provided another clue that somewhere in the area the fungus had taken hold.
WDFW, with the NWHC diagnostic laboratory, also tried something novel and experimental - collecting bat droppings (guano) and testing them for Pd. Scientific research had shown that Pd could be detected in bat guano, but collecting guano as a surveillance tool for Pd was new. Together, WDFW and the NWHC identified a bridge in King County near where the infected little brown bat was found that was a night roost (where bats hang out and rest while they forage). WDFW did not know how many bats used the site, or what species, but they knew they could get guano there.
In late April they collected guano and swabbed environmental samples from under the bridge and sent them to the NWHC, but no Pd was found. Because they couldn’t be sure how old that guano was, biologists set up tarps to catch fresh guano (humorously dubbed “crap traps”), and waited.
In mid-July they collected the guano, but this time testing at NWHC identified a
sample positive for the DNA of Pd. Because it was a “pooled sample” (guano from an unknown number of bats deposited over a period of time) questions remain about the timing and species of bat infected. The NWHC is trying to determine which species of bat or bats produced the positive guano. However, if the sample contains DNA from several bat species, we will still not be able to determine which species had come into contact with Pd. It remains unknown where the bat(s) may have come into contact with the fungus or how long ago.
We still have a lot to learn about western bats and how WNS might affect them. Working together with partners to develop new disease surveillance and population monitoring techniques is critical to understanding similarities and differences in the ways that WNS may affect western versus eastern bat populations.
Whether it is implementing the latest techniques that science has to offer, or developing and evaluating cutting-edge new technologies, partners in western states continue to work together to meet unique challenges of detecting Pd and WNS and conserving our western bats.