Washington bat population at risk by new disease introduced from East Coast
Rachel Blomker, the communications manager with the Washington Department of Fish and Wildlife poses for a portrait with a Townsend’s big-eared bat at the WET Science Center. // Photo by Emily Feek
By Emily Feek
Washington bats now face the threat of white-nose syndrome, a deadly fungal disease that has killed an estimated 6.7 million bats as of 2011, according to the white-nose syndrome national webpage.
The disease spread to Washington from the East Coast in 2016, and is not fully understood in our state, said Abby Tobin, the white-nose coordinator with the Washington Department of Fish and Wildlife.
White-nose syndrome was first confirmed in Washington in March 2016, when a hiker found a little brown bat on a trail and reported it to the Department of Fish and Wildlife, according to the department webpage.
“The first detection, the bat was just found alive by a hiker, that happened to fall on a trail,” Tobin said. “If that bat fell six feet off the trail, perhaps we might not know white-nose was here.”
White-nose syndrome is named for its characteristic white growth on bats. The fungus grows on bats’ exposed skin, giving them a fuzzy white appearance. The nose, ears and wings are often areas where the fungus will grow and cause damage, Tobin said.
Since 2016, there have been 43 confirmed cases of both white-nose syndrome and the fungus across King and Lewis counties, Tobin said. Both little brown bats and the Yuma myotis, two species native to Washington, have tested positive for white-nose syndrome, while the silver-haired bat has been confirmed to carry the fungus.
White-nose syndrome is problematic because the fungus damages the bats, which have a suppressed immune system during hibernation, and can lead to loss of wing tissue, Katherine Haman, a wildlife veterinarian with the Department of Fish and Wildlife, said. The fungus often wakes bats before their hibernation period is over, at which point they die of starvation or dehydration, Tobin said.
Researchers monitor white-nose syndrome and fungus spread by tracking groups of hibernating bats, as well as their roost locations for any signs of the fungus.
Tracking the spread of the disease in Washington has proven to be a difficult task, though.
“We have a huge, a vast amount of land to cover,” Tobin said. “We don’t know a lot about the roosting ecology of a lot of species in our state.”
White-nose syndrome has proven deadly on a massive scale in other portions of the country. The fungus spreads through bat-to-bat contact, Haman said. Because bats often roost in close quarters, the fungus is able to impact a large number of bats within a hibernaculum.
On the East Coast, where bats will roost in groups of several thousand, white-nose syndrome can kill up to 90% or more in a colony.
Because of the lack of understanding of roosting habits in Washington, the department has focused on preventing further spread of the fungus through awareness and public outreach.
The agency hosted an informational event on April 13, intended to inform families about both the ecological benefits bats provide as well as the threat white-nose syndrome poses. Rachel Blomker, communications manager with the Department Fish and Wildlife, presented information on Washington bat populations.
Part of the public outreach includes encouraging people throughout the state to report both the locations of bat roosts and any suspicious or concerning bat behavior, Blomker said. The department website has links to both reporting tools.
Haman said staff get the reports in real time and often respond within a few hours, and that people should also contact the Washington State Department of Health if there has been any human contact with the bat. People should not handle any bats themselves, she said, as bats can carry rabies.
Behavior that should be reported includes seeing bats out during the day or on the ground, Haman said.
The end of hibernation periods depends on temperature shifts, but any bat activity observed before the end of April or early May should be reported, as bats are usually still hibernating until then, Blomker said.
White-nose syndrome may not be easy to recognize because the fungus is brittle and breaks off bats once they leave hibernation and begin grooming themselves, Haman said.
Reporting the location of bat colonies and roosts is also encouraged and helps the Department of Fish and Wildlife to more effectively track the spread of white-nose syndrome. Biologists working with department use these locations to collect environmental samples and detect signs of the fungus, Tobin said.