For the second spring in a row, a fungus that has killed millions of bats across the country has been found in California — raising the specter of an outbreak in the state’s fragile, little-understood bat colonies.
Biologists found the fungus that causes white-nose syndrome this spring on three Little Brown Bats in the Plumas County community of Chester in northeastern California. It followed a similar detection in the same area last year.
While not dangerous to humans, the disease has the potential to devastate California’s bat populations, which are already under threat as their migration routes are blocked by wind turbines, their habitats are plowed over by urban sprawl and a host of other ecological woes, said Scott Osborn, a bat expert with the California Department of Fish and Wildlife.
“There are a lot of problems for bats these days,” Osborn said.
The possibility of white-nose syndrome infecting the state’s bats also could have wide-ranging consequences for Californians.
One American bat species — the northern long-earned bat — already is protected under the federal Endangered Species Act as colonies collapsed from white-nose syndrome as it rapidly spread across more than two dozen eastern states in just 13 years. Some other protected bat species’ were further imperiled because of the disease, leading to restrictions on building and road projects that would have imperiled their habitats.
Despite being vilified for centuries as harbingers of evil, bats such as those in Chester provide an important ecological function that benefits people: they eat flying insects such as mosquitoes, which can carry diseases. By one estimate, a single mouse-sized Little Brown Bat can eat as many as 10 mosquitoes a minute.
White-nose syndrome attacks bats that gather in colonies as they hibernate through the winter. The fungal infection has sickened bats in 33 states and seven Canadian provinces. So named because the fungus leaves a dusting of white on their noses, skin and fur, millions of bats have died from white-nose syndrome since it was first discovered in New York in 2006.
Because the bats waste precious energy fighting the infection when they’re dormant and not eating, up to 90 percent of the bats in a colony can die in the worst outbreaks.
California joins four other states where traces of the fungus have been detected on bats, but so far none have been found sickened from the disease.
In California’s case, bats might be dying from white-nose syndrome, but because so little is known about where the state’s bats spend their winters, it’s anyone’s guess where and how many colonies might be infected, Osborn said.
The three little brown bats that had traces of the fungus on their skin and fur this spring were located inside some buildings in Chester in what’s known as a “maternity colony” where female bats give birth, Osborn said.
“So it was actually kind of amazing that we detected the fungus because they’ve been out of hibernation for some period of time fighting off the fungus, and yet we were still able to detect it,” Osborn said.
How the disease got to California is a mystery, said Catherine Hibbard, spokeswoman for the US Fish and Wildlife Service’s National White-Nose Syndrome Response Team.
Washington, Wyoming and New Mexico are the nearest states where the fungus has been found, she said.
In other states, biologists suspected that people such as spelunkers brought the fungal spores into the bats’ hibernation lairs. It’s why biologists now urge anyone entering caves, caverns or mines to disinfect their shoes and gear before and after going underground.
Osborn, the California bat expert, said his fellow biologists are urging wildlife professionals such as those working for rehabilitation centers and at rabies testing laboratories to keep an eye out for signs of the disease in the bats they collect so they can be tested.
Because bats do carry rabies, it’s never a good idea to handle one, but Osborn urged people to notify a professional if they see a bat with the fungus on them, if its wing membranes are flaky or sticky, or if it otherwise don’t look right, especially those living in colder areas of the state where bats hibernate.
“Anybody who’s in a cold part of California where it freezes regularly at night ..., if they find a bat outside in the winter, there’s something wrong,” Osborn said.
Meanwhile, Osborn said researchers are ramping up their bat population studies in California, and they plan this fall to place telemetry devices on the bats in the Chester area so they can trace them back to where they hibernate.