From bunkers to bat caves by Doug Reed

From ANIMAL PEOPLE, April 1993:

NEWINGTON, N.H. –– The weapons storage
area lies brooding at the core of the Great Bay National
Wildlife Refuge, surrounded by an eight-foot-high chain
link fence capped with barbed wire and razor wire. Thirty
concrete block buildings, 250 power poles, miles of wire,
and 15 weapons storage bunkers––fortified cement crypts
covered with earth and grass––crowd the site with silence.
Clustered at the far end of the 62-acre storage
area, the bunkers are empty of the missiles and explosives
stored there for the past 30 years. The double steel doors
are six inches thick and weigh five tons each. A heavy-
duty hydraulic jack opens one door, and visitors, mostly
members of the Audubon Society of New Hampshire,
wander into the dark. Jim Halpin, the manager of this new
refuge, explains that the U.S. Fish and Wildlife Service is
exploring the bunkers’ potential as bat caves. It’s an ironic
exchange of wildlife for arms: bats for bombs.

The U.S. Air Force transferred 1,095 acres of the
4,254-acre former Pease Air Force Base to the USFWS in
August 1992. Including six miles of undeveloped shore-
line close to Hampton Beach, a leading tourist attraction,
the base was closed in March 1991. After considerable
political struggle, the shoreline was included in the refuge.
About 2,700 acres of the remaining land will be sold;
another 500, saturated with jet fuel, are off limits as a
toxic waste site. A cleanup plan is to be finished by 1994.
The newly created Great Bay refuge was dedicat-
ed October 9. The ASNH has assisted the USFWS in
developing wildlife management plans. Of particular
interest to members were efforts to maintain the nesting
sites of upland sandpipers and ospreys, and to protect a
perch site for wintering bald eagles. Loons and black
ducks are also to be protected, though black ducks are
heavily hunted on Great Bay itself.
The bunker we explored on September 19 does
feel like a deep bat cave. It’s dark, damp, about 60 feet
long, 20 feet wide, and 15 feet high at the top of the
arched ceiling. The smooth concrete surface glistens with
condensation from the warm air entering the open door.
At the far end, we could just make out the weapon capaci-
ty figures painted high on the wall: TYPE 1.1 –– LIMIT
86,000 lbs. The other four types are all listed UNLIMIT-
ED. Since bats can hibernate in dense clusters of 300 indi-
viduals per square foot, one bunker could conceivably
house a colony of 100,000. But why bats, and what
would attract them to this place, when New England bats
usually roost in steeples and beneath the eaves of barns?
According to Boston University biologist Dr.
Thomas Kunz, “Bats have naturally occupied old bunkers,
but mostly in the southern states where temperatures are
higher.” Bats of the northeast require warmer tempera-
tures for summer roosting and rearing young than are like-
ly to be maintained within the Great Bay bunkers.
“The first question,” Kunz says, “is ‘what are
the normal summer and winter conditions?'”
Agrees Massachusetts Department of Fish and
Game biologist Tom French, “You have to put thermome-
ters in the bunkers first, and monitor the temperatures
through the seasons.”
There are no cave-breeding bats in the northeast,
as caves are just too cool in this region for the young. In
the winter, however, large colonies of bats do hibernate in
caves and mines. Chester Mine in Massachusetts attracts
2,500 bats each fall, as “the largest known hibernaculum
in New England,” according to French.
Bat Conservation International director Dr.
Merlin Tuttle and a group of BCI biologists hope to con-
vert one bunker into a summer roosting chamber with a
new entrance, proper ventilation, and carefully spaced
wooden slats hanging from the ceiling. Bats may move
into the new home if they find it attractive. However,
Tuttle cautions that, “Anything you do will be highly
experimental. There has been very little research on alter-
native roosting for bats, and there are no guarantees.”
In fact, the University of Florida at Gainesville
was badly embarrassed in 1991 after spending $30,000 on
a special bat tower, intended to replace roosting areas
destroyed during extensive stadium renovations. About
2,000 of the estimated 10,000 bats who were expected to
live in the tower actually remained there, briefly, after
they were live-trapped and released inside. Within two
months, however, all the bats were off to parts unknown.
There is a backup strategy for the Great Bay
bunkers. If the conditions are not right for raising young,
but are within the range for hibernation, the former
weapons storage chamber may bcome a hibernaculum––a
winter bat cave.
Whatever the conditions, the USFWS prelimi-
nary plan calls for managing the high-security wildlife
reserve “to restore threatened and endangered species.”
As we turned to leave, I noticed a narrow trail in
the grass and followed it up the steep bank to the top of the
bunker. There, with a strategic overlook, was the
entrance to a woodchuck’s burrow.
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