Cruel pastime threatens bat populations

Disturbance by humans during the winter hibernation period is decimating the population of two species of bats that live in lava caves in southern Idaho.

The two species are Townsend’s big-eared bats and Western small-footed bats. According to the Bureau of Land Management, both species have declined throughout the West, and Idaho caves provide homes for some of the largest remaining colonies.

In an attempt to reverse the decline, the Bureau of Land Management is closing 12 caves to visitation this winter.

"Hibernating bats reduce their heart rate and lower their metabolism so that they can survive through the winter when insects are not available," Call said. "They draw on stored body fat obtained by eating enormous amounts of insects all summer and fall.

"When people enter hibernation sites, bats respond by revving up their metabolism and burning relatively huge amounts of body fat. Bats that are disturbed can very easily starve to death before insects are available in the spring."

One of the principal bat caves is Gypsum Cave, northeast of Shoshone. So named after its extensive gypsum deposits, the cave consists of 2.5 miles of tunnels over six levels.

Call said the BLM has had a sign placed at Gypsum Cave’s mouth from October through May each year informing people that the cave is closed during that time. However, she said, the sign has often been ignored.

Call said the decline of bats in Gypsum Cave has been exacerbated by a warped pastime known locally as "bat bopping." Bat bopping consists of clubbing hibernating bats to death with baseball bats.

Call said that over the past few years, the bats’ population in the cave has declined by about three-quarters, and at last count numbers 168 animals.

The BLM took stronger measures to protect the bats there 10 days ago with the erection of a gate across the cave’s mouth. The project was done with the help of 30 volunteers on Saturday, Sept. 26, designated by the government as National Public Lands Day. Call said the designation is an effort by all federal land-management agencies to recruit volunteers to do something substantial to help restore public lands.

She said the Gypsum Cave volunteers also picked up litter, scrubbed painted graffiti from the cave’s walls and marked trails around several sensitive areas.

Call said the locked gate consists of metal bars placed six inches apart—the minimum width bats appear willing to fly through.

"It’s as vandal-resistant as we could make it and still make it friendly to bats," she said.

Call said the BLM has also been giving presentations in local schools to inform children that bats are harmless and beneficial to the ecosystem. Call said the bats are voracious consumers of night-flying insects. The insects not only annoy people but damage crops and forests, she said.

Call said anyone wishing to visit Gypsum Cave can do so during the summer by picking up a key from the BLM’s Shoshone office. She said cavers need to wear hard hats and gloves and carry three light sources each.