Cave-gating is the latest tactic in the struggle to halt declines in the numbers of two endangered "flying mice.
A DIFFICULT PROBLEM needs "fairly drastic action," and Daniel Boone National Forest's John MacGregor is faced with one: Protecting the privacy of resident bats. For two species of these "flying mice," this action preserves more than just beauty sleep: It can mean the difference between life and death.
"The problem here is that we're looking at the extinction of at least one bat species--the Virginia big-ear--within the next 10 or 15 years if something isn't done to save the only two major remaining populations," says MacGregor, endangered-species specialist for the national forest in eastern Kentucky. "Next to go could be the Indiana bat."
The populations are dwindling for several reasons, the main one being "human disturbance" to hibernating and nesting colonies, according to Larry Martoglio, a 26-year Forest Service veteran and wildlife staff officer at Daniel Boone. The bats are also adversely affected by habitat destruction, direct killing, vandalism, and the use of pesticides on their food--insects.
Both the Virginia big-ear bat, a five-inch-long, chocolate-colored creature with mule-like ears, and the flat-faced, three-inch-long Indiana bat are currently listed as federally endangered. One colony of Virginia big-ear bats winters in a cave on private land in West Virginia, the other in Stillhouse Cave on the 670,000-acre Daniel Boone.
The "drastic action" MacGregor refers to is the fairly new practice of "gating" bat caves--closing off entrances to everyone except resident bats. The slatted gates, made of quarter-inch angle iron, allow for normal air flow through the cave and don't change ambient temperatures. A gated cave retains all its normal conditions; the only difference is that vandals can no longer get in to destroy the bats or their habitat. Well-intentioned folks such as spelunkers and biologists can't get close enough to the furry creatures to cause problems either, MacGregor says.
"Even if a bat colony is disturbed unintentionally, the results can still be disastrous," Martoglio says. "When bats are awakened from hibernation, they use up their store of winter fat needed to sustain them until their insect food source is available in the spring." One arousal costs a bat as much energy as it would need for two or three weeks of hibernation. If there are enough arousals, the bat can starve.
Disturbing maternity colonies when newborns are still too young to fly can be equally damaging. When a parent bat is bothered, it can panic and drop or abandon its young, resulting in the little one's death, Martoglio says.
Although a number of bat species are endangered in other parts of the country, gating is not widely practiced outside Kentucky, though it may be eventually. (Throughout the United States only about 70 bat caves have been gated, MacGregor says.) Currently nine Kentucky caves have received 11 gates. Four were placed on bat caves within the Daniel Boone with two more possible in the near future, MacGregor says. The oldest "successful gating" was done only four years ago, but bat censuses already indicate dramatic population gains.
In 1983, the U.S. Fish and Wildlife Service prepared Recovery Plans for Virginia big-ear bats, Indiana bats, and others, and formed a Recovery Team made up of bat experts who recommended gating or fencing important bat caves and placing warning/interpretive signs in others, Martoglio says. The stout angle-iron gates, which cover cave entrances, were designed by Roy Powers of the American Cave Conservation Association and Robert Currie of the U. …