Wildlife Watch: Biologists count hibernating bats

Published: Feb. 4, 2020 at 2:30 PM EST
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Bats, like some other mammals, hibernate during the winter. Our Ike Bendavid joined Vermont Fish and Wildlife biologists in Rutland County to check on all six hibernating species of bats in Vermont, five of which are threatened or endangered.

After a half-mile walk to an undisclosed location on private property, Vermont Fish and Wildlife biologists Alyssa Bennett and Joel Flewelling have led us to a cave.

"We are going underground to this small site doing a census essentially," Bennett said. "We are going to be counting the number and species of bats that we see here so we can monitor the change in population that we see over time."

Reporter Ike Bendavid: How important is this -- why go in a cave in the middle of winter?

Joel Flewelling: Well, the wintertime is the opportune time for us to get a handle on how these bats are doing because they are concentrated. If we tried surveying the bats out in a landscape they are much more spread out and difficult to catch.

Reporter Ike Bendavid: Why are we whispering right now?

Alyssa Bennett: We are trying to be quiet because we are sitting right outside of a hibernation site for bats and they are in this resting period for the winter where they are saving energy so they are really prone to disturbance from noise, light, vibration, things like that, so we try to keep that to a minimum.

On this day there are two caves to check. And even though it's freezing outside, inside the cave it's a different story.

"The cave remains the same temperature year-round," Flewelling said. "It's in the high 40s. So, a day like today you can see the steam rising from the cave with that warm moist air."

Once geared up, Bennett and Flewelling crawl down or even rappel down into the cave.

"It's wet and cold and dark and muddy down there so we want to be dressed appropriately," Flewelling said.

Underground, the crew makes their way around the tight corners nearly 50-feet below the surface. Once they find the bats on the ceiling, the count begins.

After being hit hard by white nose syndrome starting around 2008, the bat population seems to have stabilized.

After about 25 minutes underground, the crew emerges from the cave.

Reporter Ike Bendavid: How did that go? What were the numbers for bats in the cave?

Joel Flewelling: Very comparable to the last time we were here. They are just hanging on those low numbers not continuing the decline, just hanging on.

There are about a dozen bats at one location, and they credit private landowners for leaving them alone so that they can thrive. "Nearly all of our 30 known hibernation sites for bats and mines are on private lands, so these species really depend on, fundamentally, on private landowners caring about habitat and managing for the species and allowing us to do this monitoring work. So, I would say the fate of a lot of these species in the summer and the winter is resting in the hands of private landowners in Vermont," Flewelling said.

These bats will stay hibernating through April.

Reporter Ike Bendavid: How important are bats for the ecosystem in Vermont?

Alyssa Bennett: Some of that is measurable and some of that is not. What we can measure in terms of bats' importance in the ecosystem in Vermont is that they eat a lot of insects. That's important for things like pests and forests. And there are ways they contribute that we don't know how to measure yet.