Ice Box Cave closure helps the hibernating bat population recover. Photo taken by NPS Staff.
Written by Kathy Johnson for the Conservancy Member Magazine, Volume 5, Issue 1.
ICE BOX CAVE, located in the Ritchie Ledges and aptly named for its cooler temperatures, has long been a favorite spot for park visitors to cool off on a hot summer day. When it closed to the public seven years ago there was a lot of confusion as to why. A sign posted outside the cave states the stark reality—bats are dying.
Bats get a bad rap as disease-carrying, blood-sucking creatures that attack humans when, in fact, bats are gentle mammals that are more threatened by humans than we are by them. With more than seven species of bats making their home in CVNP, recent efforts to help them survive and thrive have been instituted in areas where bats live, breed and hibernate.
WHITE NOSE SYNDROME
According to Ryan Trimbath, a biological science technician in CVNP, “In 2012 Summit County had its first confirmed case of white-nose syndrome (WNS), a disease of cave hibernating bats caused by a fungus,” he said. “The fungus grows on the skin of the bats while they are hibernating, mainly on their wing membranes. Due to this we have seen a drastic decline in the number of cave hibernating bats in this area.”
WNS, which was originally discovered in New York state in 2007, has spread to 36 additional states and five Canadian provinces and has had a devastating effect on this population of bats—killing millions of bats and wiping them out completely in some regions.
Meg Plona, a biologist who works in CVNP’s resource management division, says WNS is a cold weather loving fungus characterized by a visible white growth on the bat’s muzzle and wing tissue.
“The fungus makes them itchy; kind of like poison ivy does in humans. It also causes dehydration,” said Plona. “When bats are hibernating, their body systems slow down because they are storing their energy. Any bit of movement or flying uses up energy stores and can have devastating effects.”
Hibernation, by design, is meant to keep the bats in a state of torpor (reducing the bat’s temperature, heart and metabolic rate to help it survive the long winter).
“Infected bats will display abnormal behaviors during their hibernation period which can lead them to wake up early and leave their roost to look for water,” said Trimbath. “With little energy and no food supply in winter months, these confused bats may not make it back to their hibernation site and/or die of starvation in the process.”
Ice Box Cave, a popular hibernation spot for little brown bats—one of the species most affected by WNS—was closed in an effort to reduce the spread of WNS and to keep people from inadvertently disturbing these bats during hibernation.
“Anything that increases a bat’s stress contributes to its chances of not surviving hibernation season,” Trimbath said. “While WNS is mainly spread from bat-to-bat, people can also transport the fungal spores on their shoes and clothes from contaminated sites to new sites. WNS poses no threat to the health of humans.”
Although 12 confirmed bat species have been identified with diagnostic symptoms of WNS in North America, the species at the highest risk are those that cluster together and hibernate in caves and mines. Efforts to protect remnant populations and promote population recovery have become a top priority in CVNP.
BAT CONSERVATION EFFORTS
One of the ways CVNP is contributing to the region’s bat conservation efforts includes surveying bat populations in the parks.
“We are participating in a statewide study to monitor maternity roosts,” said Trimbath. “We count the bats emerging from the roost early in the breeding season and then we count them again later in the year. Increases in the number of bats in the second survey reflect the number of babies that were born. By monitoring the roost site, we are able to capture the reproduction rate.”
Roosts are where bats raise their young. Bats mate in the fall when they come together and swarm near caves. Females leave hibernation sites in early to mid-April, before their male counterparts, to form maternity colonies. Colonies are located in warmer roosts which helps with gestation. Baby bats, known as pups, are born in late May or early June and can fly and feed themselves within 30 days. Some of the most popular roost sites in CVNP include the Coonrad Barn, Virginia Kendall Lake Shelter, Stanford Barn and Howe Meadow Barn although some species prefer more natural settings to roost like under peeling bark or in hollowed out trees.
“With most bat species only producing one pup a year, and a lifespan of 7–20 years, the growth rate for the bat population will take years to recover from the devastating effects of WNS.”
With most bat species only producing one pup per year, and a lifespan of 7–20 years, the growth rate for the bat population will take years to recover from the devastating effects of WNS. However, there is good news.
“Researchers investigated Ice Box Cave in early February of this year and there are promising signs that we are starting to see bats return,” Plona said. “The researchers installed data loggers in the cave to continuously monitor the temperature throughout the year. This will help them understand how much temperature fluctuations in the caves affect the remnant populations.”
During summer months bats increase their body mass by 25 percent to 40 percent—often eating 100 percent of their body weight in insects every night—in order to prepare for winter hibernation.
“Bats contribute to the biodiversity of CVNP and they benefit both humans and agriculture by eating pests. In tropical and desert climates bats are important pollinators of flowers and trees,” said Plona.
A 2017 report from the Ohio Division of Wildlife says bats are estimated to save around $3.7 billion each year for the agriculture industry by reducing pesticide loads and crop damage.
MONITORING THE BAT POPULATION
Another way CVNP is monitoring changes to Ohio’s bat population is via acoustic surveys and mist netting.
“Acoustic monitoring uses Anabat detectors which can pick up bat calls and identify the presence of a certain species of bats in the area,” said Trimbath. “Bats like to chatter back and forth. It’s their way of sharing information
and being social.”
“The park also uses mist-netting in corridors and tree canopies that bats use for travel,” Plona said. “With the help of staff from the Cleveland Metroparks, who have expertise in bat handling, we capture bats in mist nets and get bats in our hands where we can look at their reproductive condition, weigh and measure them and identify their species.”
Results of the most recent mist-netting survey showed a significant decline in the number of northern long-eared bat, little brown bat and the tri-colored bat, while other species—specifically the big brown bat and tree bats (such as the red bat and the hoary bat)—continue to thrive.
Another sign of good news was scarring found on the wings of some cave hibernating bats that were captured via mist netting.
“Upon physical examination some bats showed scarring to their wings which is an indication that they survived a bout with WNS,” said Plona. “This is a hopeful sign of resiliency.”
Research is underway at a national level to see if UV lighting, temperature changes, vaccines or spraying antifungal agents could help stop the spread of the disease. However, some experts warn that killing off the fungus that causes WNS could have a chain reaction and kill off other fungi or microorganisms that are important to the environment. Also, treated bats could potentially become re-infected.
PROTECTING THEIR HABITATS
During the May through October breeding season, park staff take extra precautions in order not to disturb any bat habitats.
“Often we will get calls from people about dead trees that they want us to take down,” Trimbath said. “But that tree could be an important bat habitat so we may need to wait until breeding season is over to remove it.”
The northern long-eared bat, normally a tree rooster, has also been found using human-made structures for roosting. Buildings and other structures give bats what they need: crevices, stable warm temperatures, microclimate options, predator protection and replacement roosts—because bats are losing natural roosts in caves and forests at a rapid rate and have adapted well to human-made structures.
“Bats may roost in attics, in dropped ceilings, in boxed eaves and gables, behind siding and masonry, under roof tiles and shingles and behind shutters,” said Plona.
In order to protect the roosting bat populations in unoccupied barns and structures, no roof work is conducted in CVNP from May 1 to August 1.
Efforts to protect remnant populations remain a priority for CVNP as experts hope to uncover where hibernation populations of bats persist within the state, and if these populations are continuing to decline, have stabilized, or demonstrate evidence of recovery.
Due to this, Plona says Ice Box Cave will remain closed for the foreseeable future.
“Entry to Ice Box Cave will remain closed to park visitors and staff until further notice in an effort to continue to keep the bats safe during hibernation and promote population recovery,” she said.
WHAT CAN YOU DO?
- STAY OUT of caves and mines where bats are hibernating.
- RESPECT cave closures.
- FOLLOW the National WNS Decontamination Protocol. Spores can last a long time on surfaces such as clothes, shoes and outdoor gear, so even though people do not get WNS, they can unknowingly move the fungus from one place to another.
- REPORT bats showing signs of WNS, and bats that are dead, dying or appear diseased, by calling 440-546-5945.
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