WYKOFF — News from the first bat survey in eight years at Mystery Cave was good. The number of bats counted was what was expected, and cavers found no sign of white nose syndrome.
Warren Netherton, however, fears that won't last.
Netherson, manager of the cave that is part of Forestville/Mystery Cave State Park, is confident numbers will stay level in future counts, but he's pessimistic about the bat-killing fungus.
The population of bats, mostly little brown bats, leveled off about a decade ago because the number of people going into the cave in winter and disturbing them was severely limited, Without noise, lights and body heat from humans to disturb them, bats don't use up life-giving fat reserves, he said. Twenty-three cavers, both experienced and novices, found 2,230 bats on Saturday, compared with 2,054 in 2005 and 2,050 in 2001 but 1,162 in 1989.
The bats use about nine specific areas in the large cave complex because those areas have the right temperature and humidity. "They need quiet, cold, dark places," he said.
Bats that hibernate in caves are susceptible to the fungus, said Dan Nolfi, a bat expert with the U.S. Fish & Wildlife Service who took part in Saturday's survey. Tree bats, which migrate, don't get white nose syndrome. Apparently, the hibernating bats' immune system is lower, along with their body temperature, he said.
The fungus is working its way west, showing no signs of abating. Until a few months ago, it was thought the closest fungus was about 350 miles away in northeast Missouri. But recently, it was found inside a cave, but not on bats themselves, in Maquoketa Cave in Iowa, about 150 miles away.
"It's a mystery how to fix it," Nolfi said.
It's an exotic fungus from Europe that got to the United States via humans. "It's like a European bat packed up its bags and came to the U.S.," he said. "Any kind of exotic coming into a new system tends to wreak havoc on it."
The fungus eats through the skin, "it is basically consuming it," he said. That can kill them outright, or they lose water and dehydrate, or wake up and move around, using up body fat.
"The bats could be starving to death," he said. "It's grim." Mortality is at least 90 percent, and there is nothing to suggest it won't be as virulent if it gets to Mystery Cave
The syndrome comes on top of other problems for bats, he said. "Bats across the planet have been persecuted by humans forever," he said. Because of that, and loss of habitat, their numbers are generally declining across the world.
"We are going to work to protect bats for a long, long, long time, probably forever," Nolfi said.
Whenever he can, he preaches about how great bats are, how diverse they are and how many insects they eat. The bats from Mystery Cave, for example, eat about 30 pounds of insects at night during the warm months. Worldwide, bats provide millions or billions of dollars in benefits, he said.
And they are fascinating because they are the most diverse mammal on earth, he said.
For Saturday's count, and to swab some bats for the fungus, the 23 cavers were divided into several groups, with some leaving early, other later so they could get to the major roosting areas around the same time. It was like a military operation, with Netherton the general. His idea was to "get in fast and get out fast."
But fast in a cave is a relative term. It's easy to walk around the part with lights and paved corridors, the part most people see when visiting the cave. But to find the bats, most of the people had to go wild caving, meaning they would have to gingerly walk over mud-slick rocks, slide on their bellies or squeeze through tight passages and be ready to get really really muddy. The only light was from helmet lights or small flashlights.
Jeff Brandon, of Duluth, was more than eager to volunteer.
He comes to Mystery Cave every third weekend to explore new areas and expand the known cave passages (there are now 13 miles of known passages). Because of bats, he and other cavers often must take circuitous routes to avoid the nine major roosting areas.
It's a physical challenge but not dangerous if done right, he said.
"I love to cave," he said. "I love being underground, there are such beautiful features at the lakes."