Forest Service closes Colorado caves to limit spread of bat disease that has killed millions of animals
"This is definitely a surge. Imagine Colorado is a big rock sitting on a beach and the waves coming in around it are this disease," said Daniel Neubaum, the species conservation manager dealing with bats for Colorado Parks and Wildlife. "That's what we are seeing. We are probably going to see the disease trickle down from the north and I think the western parts of the state will be the last places we detect it in Colorado."
The Forest Service's Rocky Mountain Region — spanning 17 national forests and seven national grasslands in Colorado, Kansas, Nebraska and most of South Dakota and Wyoming — last month issued a three-year order detailing closures for 88 caves, including 16 caves in Colorado's White River National Forest. All but 11 of the 88 caves only are closed for part of the year to protect bats during their hibernation and fall swarming. (Swarming is when bats gather for mating and teaching young bats how to set up for hibernation.)
Since 2006, white-nose syndrome has been detected in bats in 40 states and nine Canadian provinces. Out East, the rapid spread of the deadly disease has led federal land managers to close most all caves and historic mines to all public access year round.
The land managers in eastern states went with full closures – not seasonal – because 90% to 100% of bats were dying as the disease and the fungus that causes the disease — Pseudogymnoascus destructans, or Pd — hopped from cave to cave.
In the West, land managers prefer to issue closures during biologically important months, when the bats are hibernating or swarming, while allowing access during other months.
If humans enter caves when bats are hibernating, the bats awaken and leave the cave.
"If they are trying to fight off the fungus, that could be double trouble for them," said Melissa Dressen, a wildlife biologist with the Forest Service.
Protecting access for the vibrant caver community and state wildlife officials is critical for Forest Service officials as they track the spread of white-nose syndrome in the mountainous West, where bats are more dispersed and tend to hibernate in smaller groups in cracks, crevices and mine shafts versus the big caves out East where they hang out in the thousands.
Cavers arguably have the most to lose than any other humans when it comes to cave closures. But they have been instrumental in helping state and federal wildlife biologists track the spread of the Pd fungus and detail the locations where bats roost and hibernate. Cavers often help biologists reach remote caves as well.
"Cavers are fascinated by curiosity and learning and that's tempered by conservation. We don't want to destroy something we love," said Jennifer Zedalis, the chair of the Colorado Cave Survey, which represents seven regional grottos, or caving groups in the state that are members of the National Speleological Society. The Colorado Save Survey works with landowners and federal agencies to protect cave resources and access.
Since 2010, when Western land managers began closing all access to caves to prevent the spread of white-nose syndrome, cave explorers have been helping biologists map caves and collect guano and fungal spores for testing. Cavers also are able to report underground spaces where bats do not hang out, so those caves have been excluded from closure orders.
"Early on in the spread of the disease, the caving community recognized that there was potential for it to affect their ability to visit these sites and they got engaged very early. Not only did they learn how to not spread the fungus but they also engaged with agencies to help make informed decisions," Neubaum said. "I've relied heavily on the cavers and their experiences in getting to these sites and sampling them. Without their help, we would not have been able to reach a lot of these sites."
The cavers "might have a lot to lose but they also care a lot about the bats and they want to do what's best for the bats," Dressen said.
Rock climbers and citizen scientists, like the cavers, are helping Colorado's wildlife biologists study bats. The Climbers for Bat Conservation group has helped land managers identify remote bat hibernation sites on sheer cliffs. The Colorado Bat Watch organization connects biologists with volunteers to enable easy reporting of bat roosting sites and colonies.
"Generally speaking the Forest Service does rely a lot on citizen scientists in our conservation work," Rocky Mountain Region spokeswoman Donna Nemeth said.
The Rocky Mountain Region closure order includes requirements for cave visitors that includes:
The Rocky Mountain Region order issued last month includes 46 more caves than the region's 2021 closure order . But back then, white-nose syndrome had not been detected in Colorado and most of its surrounding states. This spring, tests on eight different species of bats yielded 32 positive results for white-nose Syndrome, all between Fort Collins and Colorado Springs. Most of the sick bats were little brown bats , but one was a fringe-tailed myotis bat and another was a big brown bat . (Apparently there's little creativity deployed when naming some bats.)
Neubaum said biologists are closely watching Colorado, curious if the state's climate and ecology might slow the spread. Also the state's bat populations are much more fragmented in Colorado than in eastern states.
"Our microclimates and temperatures and humidities might not be as conducive to fungus and growth as caves and mines in other portions of the country where it spreads really quickly," he said. "So that's a ray of hope."
If the disease does spread more slowly in Colorado, bats might have time to adapt. That's already happening in Europe, where bats are acclimating and developing a defense to the Pd fungus. And here in Colorado, biologists have been deploying a fungus-fighting vaccine on bats as a test program.
That involves catching as many bats as possible, putting a small passive integrated transponder tag chip in them and giving half the group a vaccine. Then the biologists have been tracking the bats as they migrate across the state. Early results are "super positive," Neubaum said.
"The vaccinated bats are responding well with no negative reactions and they appear to be surviving the challenges of fungal exposure very well so we are really hopeful," he said.
Cavers also have been helping biologists map caves and collect guano and fungal spores for testing. Cavers also are able to report underground spaces where bats do not hang out, so those caves have been excluded from closure orders.
"Early on in the spread of the disease, the caving community recognized the there was potential for it to affect their ability to visit these sites and they got engaged very early. Not only did they learn how to not spread the fungus but they also engaged with agencies to help make informed decisions," Neubaum said. "I've relied heavily on the cavers and their experiences in getting to these sites and sampling them. Without their help, we would not have been able to reach a lot of these sites."
The caving community watched the steady westward march of the Pd fungus "with bated breath," Zedalis said.
"We have felt this wave coming for a long time," she said. "We want to play a role in protecting these species and we try to be the frontline for observations for scientists. Now it's here and we need to educate the general public on how we can help protect bats and caves. It's not like a forest. Once a cave is damaged or destroyed, it's pretty much gone for good."
