Bats of the United States and Canada

Threats to Bats

recto runninghead 59 Threats to Bats In the United States and Canada, several animals, including owls, hawks, raccoons, skunks, feral cats, and snakes prey on bats. But relatively few animals consume bats as a regular part of their diet. Humans seem to be the only animal having a significant impact on populations of bats. Adverse impacts from humans include habitat destruction, direct killing, vandalism, disturbance of hibernating and maternity colonies, and use of pesticides (on their food, i.e., insects) and other chemical toxicants. Drastic reductions in populations of bats have occurred during recent years in the United States, Canada, and worldwide . In other parts of the world, there are animals that specialize on bats as food, for example, the bat hawk, Macheiramphus alcinus, found in sub-Saharan Africa and in southern Asia to New Guinea. A Trans-Pecos rat snake feeding on a Brazilian free-tailed bat (Tadarida brasiliensis). Snakes often visit openings of caves to eat bats. Gates across openings, constructed to protect bats from disturbance by humans, often facilitate capture of bats by snakes. J. Scott Altenbach 60 bats of the united states and canada Hubbard’s Cave, owned by the Nature Conservancy of Tennessee, serves as a hibernation roost for over half a million endangered gray bats (Myotis grisescens), as well as six other species of bats. The cave was gated in 1985 to protect its bats. In 2006, the Conservancy replaced that gate with the stateof -the-art cave gate shown here. Nature Conservancy photo by Cory Holliday This chute-type gate at the entrance to Tumbling Creek Cave at the Ozark Underground Laboratory in Missouri was constructed to protect a large maternity colony of endangered gray bats (Myotis grisescens) from disturbance by humans. Michael J. Harvey recto runninghead 61 Disturbance to hibernation and maternity colonies by humans is a significant factor in the decline of many species of bats. Even wellmeaning individuals such as spelunkers and biologists cause these disturbances . Hibernating bats arouse from hibernation when disturbed by people entering their caves. When aroused, they use up precious fat needed to support them until insects are again available in spring. A single arousal probably costs a bat as much energy as it would normally expend in 2–3 weeks of hibernation. Thus, if aroused often, hibernating bats may starve to death before spring. Disturbance to summer maternity colonies is also extremely detrimental . Maternity colonies cannot tolerate disturbance, especially when flightless newborn young are present. Baby bats may be dropped to their deaths or abandoned by panicked mothers if disturbance occurs during this period. threats to bats 61 ...