EAGLE AND SUMMIT COUNTIES, Colorado - Regional forester Daniel Jiron signed an extension to an emergency order Wednesday to restrict access to all caves and abandoned mines in the Rocky Mountain Region of the U.S. Forest Service.
The closures are meant to minimize the risk of the human spread of the fungus causing white-nose syndrome, which new studies indicate has killed some 5.5 million bats nationwide.
The emergency order will extend to Aug. 1, 2013.
There are roughly 30,000 abandoned mines and hundreds of caves on National Forest system lands, experts estimate.
"Once a colony is infected, white-nose syndrome spreads rapidly and can kill over 90 percent of bats within the cave in just two years," Jiron said.
White-nose syndrome 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, according to the U.S. Forest Service.
"The fungus has not yet been detected within Colorado's Rocky Mountain region, and we are taking an aggressive approach to minimizing the risk of humans inadvertently introducing the fungus into caves and abandoned mines," Jiron said.
The thought of living with a bat may be an unsettling one for many, but often bats will use residential structures as their home base - unbeknownst to their humanly hosts.
The most common bats in this area are the big brown and little brown species, which are quiet and not disruptive, according to Daniel Newbaum, terrestrial wildlife biologist with Colorado Parks and Wildlife.
"Often I've seen people that don't know they have bats for years and years until a bat that is sick shows up or they find one outside - sometimes the pups wander around when they're young," Newbaum said.
Maternity roosts, where females group together and spend most of their days, are used to give birth to pups and raise them until they are able to fly.
"Human structures work well for maternity roosting because they often get warmer than a lot of natural features that are used by bats like trees and rock," Newbaum said.
Bats are able to fall under the radar of human detection because they rarely cause damage or disruption.
"Bats don't typically do any damage like mice," Newbaum said. "They don't chew on insulation or wires - when they occupy their roosts, they are not active."
Even guano, bat droppings, lack in smell, which allows bats to remain undetected.
"Over time, guano can build up to an amount where humidity can give it odor," Newbaum said. "But the climate is so dry here that most people don't ever notice that."
Newbaum has experienced homeowners who have coexisted with bats unknowingly for a shocking amount of time.
"There was one time that I investigated an attic after a homeowner noticed a bat exiting from an opening," Newbaum said. "There was a guano pile a foot high, and they thought they only had a few bats using the area - the reality is for that kind of pile, bats would have had to have been using it for decades."
Homeowners who live in areas adjacent to national forests have a higher probability of bats targeting their homes as rest areas or roosting sites.
It doesn't take much for a bat to sneak inside of a manmade structure - often a slit as small as an eighth of an inch allows enough room to enter insulated areas, Newbaum said.
Once a bat finds a safe area to create a roosting site or a place to rest during active periods, the flying mammal remains loyal to that location.
Houses and porches serve as night roosts, used as resting spots and places to digest.
"Bats often show a lot of fidelity to a site," Newbaum said. "They'll come back year after year, and their offspring will, too."
Whether or not a homeowner allows bats to utilize their properties is another story.
"I've seen a wide range of responses to bats in houses," Newbaum said. "Some people know they're there and like them because they're not bothering them and they eat a lot of bugs. Other people want to get rid of them right away."