The Bats of Sinnett-Thorn Mountain Cave System


Sinnett-Thorn Cave is both a nursery and a hibernaculum (a place where bats hibernate) for the Virginia big ear bat, which has been designated a Federal endangered species. This species is very easily disturbed by human activity. This inability to cope with human intrusion may be one reason why the national population of these bats has been on a general decline. Some bats seem to be able to better contend with human intrusion; big ears don't.

The number of hibernating big ears in Sinnett is increasing, though it's too soon to tell if this is a trend or a short-lived increase. See the chart for the actual numbers. Note that the winter counts, highlighted in green, are conducted every other year, rather than every year. This is to help minimize disturbances to the bats.


The Myth of the Hibernating Bat

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

Hibernating bats are disturbed by even very low levels of light exposure, as has been documented in 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.

The bats will probably 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, to include light from flash cameras, off the bats.
  • Keep noise levels very low, especially when nearing the hibernation areas of the big ears.

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 might want to keep the light and noise levels at even lower levels during your next trip.

Please do not photograph the bats, even in the early fall when they are not in hibernation. Think of the bats' survival. Is your photograph worth endangering the lives of the bats? There are photographs available of all the Sinnett-Thorn species.

There are pipestrelles and other bat species hibernating in Sinnett-Thorn. Please help ensure their survival by keeping direct light off them and by keeping noise levels to a minimum. Areas of high bat concentrations are the passage near the plank bridge, and past the Connection into Thorn. However, there are bats scattered all over the cave system.

Please discuss how to help the bats with your group before entering the cave, and repeat the instructions before beginning to leave the cave. Discourage photography of the bats.

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.