“What they’re doing is a fantastic project in many ways,” said Jeremy Coleman, the national white nose coordinator for the United States Fish and Wildlife Service. “But it’s a crapshoot.” Although Mr. Holliday has consulted bat experts on every aspect of the cave — from temperature to airflow to varying the texture of walls and hanging fabric with three different sizes of mesh so that bats have something to hang on to — he believes the effort is a first.

If it works, the technique could be applied to abandoned mines and other built structures where bats hibernate. And whatever happens, the bunker is equipped with cameras and temperature sensors to study bats’ behavior and see if their choice of microclimate affects their susceptibility to the fungus.

The lack of weapons to fight the disease is not surprising, since it was only in 2006 that it was first noticed. Government agencies, research scientists and conservation groups quickly turned their attention to the problem.

The first step was determining the cause of the syndrome, which appears as a fuzzy white growth on the muzzles of sick and dying bats. David Blehert and his colleagues at the United States Geological Survey identified the culprit as a previously unknown species of fungus that they called Geomyces destructans. It is a soil fungus that thrives in the cold temperatures of caves where bats hibernate.

Fungi rarely pose a problem for healthy mammals, so there are few treatments. It’s easy enough to kill a fungus with bleach, but not when it has infected an animal. Amphibians have suffered major losses recently from another fungus. But climate change and habitat loss may have contributed stress. For bats, it seems the problem is simply that the fungus was new to the United States.

The many species of bats that do not hibernate were not affected. Hibernating bats not only have a lower metabolism and body temperature, but they are also densely packed together, so the fungus can spread easily.