Potomac Speleological Club

The Bats of Sinnett-Thorn Mountain Cave System

If the West Virginia Department of Natural Resources bat counts show a decrease in populations, access to the cave will be curtailed or eliminated. It’s up to us cavers to keep the numbers as high as possible.

Discuss how to help the bats with your group before entering the cave, and repeat the instructions before beginning to leave the cave. Photography of the bats is NOT allowed. Make sure everyone in your group knows the reasons behind this and ensure they follow the rules about caving near the bats. 

White Nose Syndrome (WNS)

This fungus, first noticed in the United States in 2006, has killed millions of bats

It can be spread by contaminated soil hitchhiking on foot gear and other caving equipment. All gear must be properly disinfected both before and after caving in Sinnett-Thorn.

Sinnett-Thorn Cave is a nursery and/or hibernaculum for several bat species: 

A downloadable brochure about West Virginia bats is available here

The Myth of the Hibernating Bat

Bats can hibernate through anything. (Wrong. Wrong. Wrong.)

Hibernating bats are disturbed by even very brief and low levels of light exposure according to at least one scientific study. Low-level noise could be a factor, too. Hibernating bats rouse occasionally on their own during hibernation, but if they are disturbed too often they will lose their energy reserves. There is no way to replenish these lost reserves in winter. In short, if disturbed too often, the bats die of starvation.

Bats may not visibly rouse immediately upon exposure to light: according to scientific research, this can take hours. This may be one reason why so many people think bats will hibernate through anything: the people are gone long before the bats are visibly roused.

How to Help the Bats of Sinnett-Thorn

  • Keep direct light, especially light from flash cameras and helmet light/flashlights, off the bats. 
  • Do not photograph the bats and don’t use cameras in areas where bats congregate.
  • Keep noise and light levels at an absolute minimum, especially when nearing the hibernation areas of the big ears. This is usually from the Sinnett entrance at the gate to the plank bridge.

If, when exiting the cave, you notice that the ears of the big ear bats are still folded up, then you know your group has done well. If the ears are extended, then the bats have been roused and you need to keep the light and noise levels at lower levels during your next trip.

Studies on Bat Disturbances

Areas of High Bat Concentrations

Virginia big ear bats hibernate in the passage between the first drop-down close to the Sinnett entrance and the plank bridge. As the weather turns colder the clusters of hibernating VBEs move closer to the entrance. These bats like hibernating in the colder areas of the cave and this seems to have helped them withstand WNS as the fungus doesn’t grow well in the colder areas of the caves. The VBE nursery is in the Big Room during the spring, summer, and fall. If the bats are still in the Big Room please keep noise and light levels low. These bats are very sensitive to human intrusion.

Tricolored bats like to hibernate on the Thorn side of the Connection as well as scattered here and there in other parts of the cave. Cavers are not allowed inside the Connection during hibernation season. 

Our goal is to demonstrate that cavers and bats can co-exist. When caving elsewhere, please be aware of the bats and apply these guidelines.