White-nose Syndrome threatening Colorado Bat Colonies

CPW terrestrial biologist April Estep, (tan uniform) and Cassidy English, CPW district wildlife manager, stretched mist nets over a drainage south of Colorado Springs on a May evening in preparation for catching and studying bats. Photo by © Bill Vogrin/CPW

In a muddy creek drainage on a chilly Sunday evening in May, Colorado Parks and Wildlife terrestrial biologist April Estep looked for a rock large enough to brace a piece of steel rebar she had hammered into the soggy ground.

Estep and CPW’s Cassidy English, a district wildlife manager, were erecting mist nets across a pool created by a sliver of water from the unnamed creek. Two nets measuring 24 feet wide and 10 feet high were already stretched across the drainage.

Mist net. Photo by © Bill Vogrin/CPW

They were anxious to finish because the sun was slipping below Pikes Peak to the west. Soon, any bats roosting in surrounding trees, rock outcroppings or mine shafts would emerge and be looking for a drink before heading out to hunt insects for the night.

Once the nets were up, Estep and English climbed out of the mud and moved to a small table they erected that would serve as their creekside laboratory for the night. On it was an assortment of scientific tools they would use if they are lucky enough to catch any bats on their overnight mission.

White-nose Syndrome

In that cold, dark drainage, Estep and English were on the front line of scientific efforts nationwide to monitor bat populations for “white-nose syndrome” – a deadly, tissue-eating fungus that grows as a fuzzy white substance on bats’ noses, wings and other hairless areas.

The syndrome is believed to have invaded the U.S. around 2006 from Europe, where bats are immune to it. It has been wiping out colonies of bats by the millions along the East Coast and in the South ever since. It has been found in 33 states and 7 Canadian provinces. And it has been detected in Wyoming, Nebraska, Kansas, Oklahoma and Texas. But it has not reached Colorado yet.

Biologists are desperate to find a way to stop it because bats are so important to the ecosystem. They are important pollinators and consume insects and may slow the spread of diseases like West Nile virus.

Colorado is h​ome to 18 species of bats including some species that migrate through in the summer. CPW biologists have spent eight years keeping vigil for evidence of white-nose syndrome as it slowly approaches Colorado.

The Waiting Game

On this night, several teams of biologists like Estep and English fanned out across a remote, wooded area south of Colorado Springs. The teams erected nets, infrared cameras and acoustic bat detectors, then waited for web-winged mammals to emerge in the dark.

For Estep and English, it was hours before a Silver-haired bat flew into their net. It was the only bat they would see that night. And they were lucky. Some of the other teams caught no bats that chilly, windy night.

There were plenty of bats flying around. But the gusting winds, Estep speculated, were causing the nets to move so much the bats could detect them with their echolocation, or bio-sonar system in which they emit a sound and listen for it to echo back off things in their environment.

Bat Survey

Finally, around 10:30 p.m., one of the mist nets rustled. Estep and English scanned the net with their headlamps and saw a small, dark figure. They ran toward it, discovered it was a bat and quickly went to work with double-gloved hands to free the bat.

The bat squealed fiercely and bit the biologists’ gloved fingers as they worked to free it from the tangled net. It took only a few moments before they deposited it in a small cloth bag. Then they hurried back to their creekside lab and went to work under the light of their headlamps and the full moon, when it emerged from swiftly passing clouds.

Estep pulled out a small scale and weighed the bat as English recorded the data. Then they measured its wings, held it on its back and examined it’s underbelly. Finally they stretched its wings over an ultraviolet light to check for signs of the fungus. And they took photos to document it top to bottom.

The bat was uninjured by being caught and examined, but it was clearly unhappy, given its squeals and repeated plunging of its tiny fangs into the biologists’ gloves. After a few minutes, it calmed down and Estep laid it on the table to rest.

Catch and Release

Once Estep and English had gathered all the data and completed the exam, they held the bat aloft hoping it would fly away. It opted to rest, instead. Since it was a tree-roosting bat, Estep placed it on the trunk of a nearby tree and it quickly scrambled up to a perch where it paused. A few moments later it took flight and disappeared into the dark.

Photo by © Bill Vogrin/CPW

The team kept the vigil until midnight, even as the temperature dropped – a spring storm dropped heavy, wet snow the next day – and no other bats appeared. But the CPW biologists took the results in stride.

“This is pretty typical of our bat surveys,” Estep said. “There are never any guarantees we’ll catch bats.”

But the work is too important to quit, even when it means not getting home until 3 a.m. after a night of slogging through mud and enduring cold wind and rain and catching just a single bat.

Protecting Our Bat Colonies

“I feel a sense of urgency to contribute to the research and stay on top of what’s happening to our bats,” Estep said. “This work is going on nationwide and we need to do our part to protect our bat colonies.”

So she and other CPW biologists will spend the summer conducting similar all-nighters in search of bats. They will drive thousands of miles criss-crossing Colorado to erect acoustic bat detectors and collect data on areas of bats and track their movements.

They will keep vigil at places like the Orient Mine in the San Luis Valley where a massive colony of 250,000 bats spend the summer. They will patrol places like Devil’s Head mountain west of Castle Rock where bats gather in its rocky outcroppings and crevices. And they will wade into the mud and muck of unnamed creeks and drainages and spend long nights catching bats, sampling tissue and guano and shining lights on wings.

“We put in the long hours in challenging conditions because we need to learn all we can as quickly as possible,” said Tina Jackson, CPW species conservation coordinator. “There is still so much we need to know about these unique animals. But due to the threats they are facing, we are working against the clock.

“White-nose syndrome is knocking on our door, so now is the time to figure out all we can about these secretive species.”

Photo by © Bill Vogrin/CPW

Jackson said CPW biologists are not discouraged when a night of research results in just a few bats being caught and studied. She said each bat provides critical data and adds to the body of knowledge.

“Netting efforts like this one, plus acoustic monitoring through the North American Bat Monitoring program as well as roost monitoring all provide important baseline information about our native bat species,” Jackson said.

“We don’t have the luxury of waiting for good weather or doing research when it’s convenient. We have to get out in the field now, before our bat populations experience too many changes from threats like white-nose syndrome, wind energy development and climate change.”

If you have bat encounters, you can phone in a report to CPW at 303-297-1192 in Denver or 719-227-5200 in Colorado Springs.


Written by Bill Vogrin. Vogrin is a public information officer for the Colorado Parks and Wildlife southeast region.

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