Oregon’s Bats Face Uncertain Future

by Jen Matteis

It’s been called the largest wildlife die-off in living memory. A deadly disease called White-Nose Syndrome has killed an estimated six million bats on the East Coast, and it’s headed west to Oregon.

“People think of it as an East Coast issue,” said Pat Ormsbee, the Forest Service bat specialist for Oregon and Washington. “Given so far how it’s traveled, there’s no reason to believe it wouldn’t come here. We are trying to get more people aware of it–we are planning as if it could get here at any time.”

White-Nose Syndrome is spread by a white, powdery fungus that appears on a bat’s wings and nose–hence the name. Originally from Europe, the disease was most likely brought over in 2006 by a tourist who visited Howe Caverns in New York, a system of caves that sees over 200,000 visitors annually.

Scientists began finding chambers filled with dead bats in New York, and then in adjoining states. The mortality rate ranges from 80 to 97 percent in affected caves and mines. In some places, it has wiped out entire colonies.

The fungus, Geomyces destructans, penetrates the bats’ skin and eats away at the delicate membranes on their wings, noses, and tails. During the winter, infected bats fly out of caves in mid-day and then die in the snow–sometimes as many as one a minute. The prevailing belief is that the fungus disrupts their metabolism and rouses them from hibernation, causing their death.

“When bats go into hibernation they have very limited fat supplies stored to get through that winter,” Ormsbee explained. “Any additional arousals cause them to use up those reserves and starve to death.”

Nine species of bats have been affected so far. Bats in the Myotis genus, which includes the big brown bat and the little brown bat, have been hit especially hard. Both bats range across the entire United States. Extinctions are a real possibility, especially as some of the bats in the Myotis genus are already considered rare in the Northwest. The little brown bat, which used to be one of the most widespread bats in the country, may soon be listed as an endangered species in the East.

“There’s places in New York where they’ve been doing summer surveys now for the little brown bat, one of our most ubiquitous bats, and they cannot pick it up acoustically–it has virtually disappeared,” said Ormsbee.

White-nose syndrome is now found in 19 states. Early in April, it reached Missouri–the first case west of the Mississippi River. It’s difficult to determine when it will arrive in Oregon–it could drift west over the course of years as bats spread the disease, or a caver could inadvertently introduce the disease. A couple “leaps and bounds” of its progression have been attributed to cavers in other states. Because of this, the Forest Service has closed thousands of caves not only on the East Coast but in the Midwest, as well as almost 30 caves in New Mexico. Although Oregon’s caves so far remain open, the U.S. Fish & Wildlife Service has asked cavers in Oregon to follow a decontamination protocol when caving (for details, visit www.fws.gov/whitenosesyndrome/cavers.html), and people are asked to stay out of abandoned mines.

“If you’re caving in the East anywhere, even if it’s in a state not yet documented with white-nose, just don’t take that gear into another state. Use entirely new gear and clothes,” Ormsbee advised. “Our intent is not to exclude the public from the caves, we want to work with those folks and help us spread the word.”

Ormsbee admits that it’s harder to control bat-to-bat transmission, but she hopes that some factor in Oregon might slow the spread of the disease. Our native bats have a few things going for them. They tend to roost in smaller groups and in more isolated locations, which should make transmission more difficult.

“There’s always a chance we have fungi or bacteria that could out-compete it here,” she added. “Maybe our bats are more resistant.”

However, Ormsbee believes it would be naïve to count on such luck. No cure exists, and no treatment, and no method of stopping it from spreading between bats. “There really is no cure,” she said. “The scientific community is working very hard to figure something out. It’s a difficult situation.”

It’s already one of the biggest catastrophes to affect a group of mammals. And losing so many bats affects more than just the bats–agriculture depends to a large degree on bats eating the insects that are considered crop pests. A bat can eat 600 mosquitoes or other insects in an hour.

For now, the plan is prevention.

“We do have a white-nose syndrome response plan for the Northwest that we’ve worked on with the federal and state agencies,” Ormsbee said. “Our big focus is prevention; let’s just not bring it out here.”

Even with cavers taking precautions, it seems likely that white-nose syndrome will eventually spread to the West Coast.

“We can hopefully support the scientific community to find a way to cure it and treat it, and in the meantime hope there’s a miracle that something out here will keep it at bay. But we can’t hang our hats on that one, that would be naïve.”

For more information, visit www.fort.usgs.gov/wns or www.opb.org/programs/ofg/segments/view/1774.