|
Because insects are not available as food during winter, temperate-zone bats survive by either migrating to warmer regions where insects are available, or by hibernating. Hibernation is a state of torpor (inactivity) during which normal metabolic activities are greatly reduced. Body temperature is reduced and heart-rate is slowed. A hibernating bat can thus survive on only a few grams of stored fat during the approximately five-to-six month hibernation period. Bats usually lose from ¼ to ½ their body weight during hibernation. Several bat species hibernate in dense clusters on cave walls or ceilings. Clusters may consist of hundreds of bats per square foot. Summer "maternity" colonies of pregnant or nursing females of several species also congregate and cluster together. Most United States cave bats spend winter hibernating in caves (or mines) and move to trees or building during summer. A few species reside in caves year-round, although they usually use different caves in summer than winter. Most cave bats are very loyal to certain caves and return year after year to the same caves, often to the exact location in the cave where they spent the previous winter. Tree bats seldom enter caves. They roost in trees during summer days and spend winter primarily in hollow trees. Several species make relatively long migration flights between winter and summer habitats. The millions of Brazilian (or Mexican) free-tailed bats (Tadarida brasiliensis) that spend the summer in southwestern United States caves, such as Carlsbad Cavern in New Mexico, migrate up to 1,300 kilometers (800 miles) to and from their winter roosts in Mexico. Information for this web site was taken almost exclusively from: Bats of the United States Published by In Cooperation with the Copies of this publication are available from the Service's Asheville, North Carolina Field Office (828) 258-3939
|
Endangered Species Home | Species Information | Laws, Policies and Federal Register Notices | ESA and What We Do | Endangered Species Bulletin | Partnerships | Contacts | Kid's Corner | Questions? | Glossary
