entertainment purposes as they emerged from caves or were caught to be used for pranks. Many property-owners attempted to exterminate entire colonies due to unsubstantiated fears that the bats may be carrying rabies. Bats that roost within 100m inside the cave and only 2m above the cave floor are especially prone to vandalism and high-intensity disturbance. Bats that roost in higher ceilings or further inside the cave are less prone to direct destruction. One study showed that caves with ceiling heights greater than 15 m above the floor were virtually protected from spelunkers. Even without direct destruction, human visitation to caves can cause adverse effects on gray bat populations. Each human entry into a cave causes all bats within range of light or sound to at least partially arouse from hibernation. Arousal of gray bats while they are hibernating can cause them to use up energy, lowering their energy reserves. Because these reserves must sustain the bats through hibernation and spring migration, if the bat runs out of reserves, it may leave the cave too soon, decreasing its chances of survival. Each disturbance during hibernation is estimated to use energy that otherwise could sustain a gray bat through 10–30 days of undisturbed hibernation. When flightless young are present in June and July, females escaping a predator or other disturbance may drop their young in the panic, leading to increased juvenile mortality. White-nose syndrome In contrast to most other species in the genus Myotis, gray bats appear to be largely unaffected by white-nose syndrome, a fungal disease that since the mid-2000s has decimated bat populations in the United States. Continuous surveys since 2009 have indicated that gray bats may be largely resistant to the disease even when sharing roosts with infected individuals of other species. Conservation Cave gating Many factors play an important role in determining a viable habitat for M. grisescens. Among these are the natural characteristics of the cave entrance, physical features of the cave, and surface climate. These contributing factors play an especially important role in determining the internal conditions that foster cave fauna. Because the gray bat is a cave dwelling species, its range is limited to caves whose internal conditions are favorable. Human intervention has caused a precipitous decline in the number of suitable caves for the gray bat. Thus, to maximize the gray bat's range, the United States government is funding cave gating programs. Cave