Forest Service extends cave closures to protect bats

The big brown bat (Eptesicus fuscus) commonly lives in man-made structures but migrates to higher elevations in winter to hibernate. It eats wasps, beetles, leafhoppers and other agricultural pests. PHOTO COURTESY NATIONAL PARK SERVICE.

Scientists still grappling with spread of deadly white nose syndrome

By Summit Voice

SUMMIT COUNTY — Caves and abandoned mines on national forest lands in the Rocky Mountain region will be closed for another year as biologists try to pinpoint risks to bat populations.

The Forest Service closed access to the caves a year ago as a preventive measure to stop the potential spread of white nose syndrome, a fungal disease that has killed at least 1 million bats in the eastern part of the country since it was detected in New York 2006.

Some signs of the disease have been spotted as far west as Missouri and Oklahoma. Wildlife biologists don’t have a good understanding of how bats migrate, and some conservation biologists have suggested that  blanket precautionary closures could prevent the spread of the fungus.

This week, acting regional forester Jerome Thomas extended the emergency order for a year, drawing grumbles from cave enthusiasts who question the effectiveness of the action. The order affects caves in Colorado, Wyoming, South Dakota, Nebraska and Kansas.

The Forest Service could probably use more targeted closures with greater effect, said Derek Bristol, vice chair of the Colorado Cave Survey. Instead of working with cavers to help with education and outreach, the Forest Service chose an approach that alienated the caving community, he said.

The regional closure affects about 70 percent of the the caves that are of interest to cavers. Bristol said his group believes about 10 percent of the caves in the region are biologically significant for bats. Focusing on managing access to those caves could be better approach, he suggested — especially since most research suggests that bats are the primary vector for the spread of the fungus.

Still, some research suggests that humans may be involved with spreading the fungus across large geographic areas.

The Forest Service is choosing the precautionary do-no-harm approach favored by conservation biologists.

“Although there has been significant progress made in science to better understand Geomyces destructans, the fungus that is understood to cause WNS, there is still much we do not know,” Thomas said in a press relase. “An extension of the closure order will allow the agency more time to better understand how the disease is migrating across the country, under what conditions it thrives, and what measures are most effective in protecting against its spread.”

“Westward migration of the disease could have far-reaching ecological impacts. Natural resource agencies are concerned because of the critical role that bats play in maintaining healthy ecosystems and in agricultural systems. Restricting access to caves and mines on lands managed by the U.S. Forest Service will help ensure regional bat populations continue to thrive,” said Steve Guertin, U.S. Fish and Wildlife Service Director of the Mountain–Prairie Region.

The agency is relying on voluntary compliance with the order since most ranger districts don’t the resources for enforcement. Education is an important component, as  biologists try to explain the importance of bats to agriculture as pollinators and in controlling insects.

The Forest Service does not have comprehensive information about where bats are roosting and hibernating, making it impossible to rule out specific caves that do not warrant closures. There are about 30,000 abandoned mines and hundreds of caves on National Forest System lands throughout the Rocky Mountain Region. In addition, National Forests in the Rocky Mountain Region support about 21 species of bats; 15 of which are hibernating bats.

Due to its geographic location, the Rocky Mountain Region of the National Forest System has a potentially key role and influence in the continued westward spread of WNS.

During the second year of the closure of caves and abandoned mines in the Rocky Mountain Region, scientists and specialists will continue their work to both monitor for signs of WNS and engage with national, regional and local efforts committed to advancing our understanding of the disease which will lead to more informed decisions for the future.

Scientists are certain transmission of WNS is occurring bat-to-bat and cave-to-bat.  Scientists also suspect transmission of WNS may be facilitated by human activity in caves where bats hibernate, because of the geographically discontinuous spread of the syndrome.  People may be inadvertently transporting fungal spores from cave to cave, as fungal spores have been detected on gear exposed to affected sites.

WNS is named for a white fungus that appears on the faces, ears, wings, and feet of hibernating bats.  The disease causes bats to come out of hibernation severely underweight, often starving before the insects on which they feed emerge in the spring.  Once a colony is infected, it spreads rapidly and can kill over 90 percent of bats within the cave in just two years.

There have been no reported human illnesses attributed to the fungus.

The Southeastern and Northeastern Cave Conservancies, National Speleological Society and many states have closed some of their caves because of WNS.  In 2009, the Forest Service closed its caves and mines in the southern and eastern United States, and they remain closed today.

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