A friend of the preserve, who happens to be a barge captain, asked an interesting question last year. “Where have all the bats gone?” He has enjoyed watching bats flying while piloting his vessel at dusk along the Ohio River every night in summers for over 25 years. The numbers of bats he was used to seeing has dropped so significantly that it has prompted his good question.
|Ohio River valley is a great place to watch bats hunting at dusk.|
We have all seen movies where an unknown virus appears and quickly spreads throughout the world, quarantining individuals while scientists rush to find its origin and a cure. A very similar scenario has been occurring under our noses (or bats noses) for the past 10 years, but this scenario is not science fiction.
|Many bats hibernate in caves in winter.|
In the early 2000’s, preserve staff started monitoring caves on the preserve. Mostly to see what animals were utilizing caves in the winter, but also to look for new species like cave salamanders, cave orb weavers, Indiana bats etc. While in the caves, we would count all roosting bats encountered and record species when possible while they were in their torpor (inactive state) for hibernation. During hibernation they would slow their metabolism down to preserve energy. Each year, we would find roughly 30-60 bats in our largest cave. Species like little brown (Myotis lucifugus), tri-colored (Perimyotis subflavus), big brown (Eptesicus fuscus) and long-eared (Myotis septentrionalis) bats were the most common.
|In 2007, it was common to see 15 bats on one wall in some of our caves. (Photo by Rich McCarty)|
|Bats would sometimes congregate in clumps, unfortunately making it easier to spread diseases. (Photo by Rich McCarty)|
In 2007, a fungus that kills hibernating bats called Pseudogymnoascus destructans or white-nose syndrome was discovered in New York. It spread quickly, and by 2011 in was found in Ohio. This fungus has been linked to the deaths of an unknown number of bats, undoubtedly millions. Because of this, and the possibility of moving the fungus spores around, we stopped entering the caves in the winter.
|Map showing the spread of white-nose syndrome since 2006. Copied from whitenosesyndrome.org|
The annoying fungus causes the bats to wake up more often during hibernation. This depletes their energy reserves so much that they die before spring emergence. Once a bat has the spores on them, they can easily carry the spores and transfer the fungus to other bats. This newly discovered fungus, origin unknown, started spreading throughout the eastern U.S. before anyone knew about it. More than 10 years later, many bat species, like the ones mentioned above, have population densities only fractions of what they used to be.
|A big brown bat Eptecicus fuscus, roosting in a crack|
|Bat researchers from Ohio University measuring temperature of a big brown bat in a cave entrance.|
The Ohio Division of Wildlife has been re-surveying caves in Ohio to monitor the status of bats in the state. This winter we guided them to some of the preserve’s caves previously surveyed almost 10 years ago. Out of 4 caves visited, the crew only found one live big brown bat. In our largest cave that used to produce the most bats, they found one dead tri-colored bat, with "white stuff" on its face. It appears, like most of the state, White-nose syndrome has found its way here too.
|Division of Wildlife employee Erin Hazelton squeezes into Fern Cave on the preserve.|
|After searching for bats, Erin Hazelton (ODW), exits Fern Cave.|
|It takes a lot of work and I'd say bravery to get into some of these cave openings.|
Unfortunately, there is no cure right now to protect bats exposed to white-nose syndrome. The fungus is here and easily transmitted between bat roosts. The state and federal agencies will continue to monitor and study this problem. Time will tell whether hibernating bats will outlast this onslaught of an invading fungus.
Posted by: Mark Zloba