Gray Bat: Myotis grisescens
Genus/Species: Myotis grisescens
Common Name: Gray bat
Federal Status: Endangered
FL Status: Federally-designated Endangered
FNAI Ranks: G3/S1 (Globally: Rare/State: Critically Imperiled)
IUCN Status: NT (Near Threatened)
The gray bat can reach a body length of 3.5 inches (8.9 centimeters), a wingspan of 9-11 inches (22.9-27.9 centimeters) and a forearm length of 1.8 inches (4.6 centimeters). Although typically gray, the fur can turn to a reddish-brown color during the summer (Florida Natural Areas Inventory 2001, USFWS Species Profile, n.d.). Gray bats also have a calcar (spur of cartilage) on their foot, which is used for stability during flight.
The diet of the gray bat primarily consists of insects, including moths and beetles. Bats are nocturnal hunters, typically remaining inactive throughout the day and flying at night to hunt. During extended periods of inactivity, bats go into a state of reduced activity called torpor. During torpor, they decrease their heart rate and body temperature to conserve energy.
Gray bats reach sexual maturity at the age of two years, which makes it one of the slowest maturing small mammals. The gray bat breeds before hibernation begins (in the winter) and the female bats retain sperm until spring when eggs are fertilized. Pregnant females form nursing colonies, which contain few male bats. It is not known why exactly males can be found in nursing colonies. Females migrate to their nursing colonies in the spring where they give birth to one pup. Offspring are weaned at two months old (Harriman and Shefferly 2003).
Habitat and Distribution
The gray bat inhabits caves and feeds over waterways that are surrounded by forests (Florida Natural Areas Inventory 2001). This species can be found in Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Mississippi, Missouri, North Carolina, Oklahoma, Tennessee, Virginia, and West Virginia (U.S. Fish & Wildlife Service Species Information, n.d.). In Florida, the gray bat is only found in the Panhandle.
The main threat to the gray bat has been disturbance of caves that are used for hibernation and rearing young. Bats in nursing caves cannot withstand much disturbance. If disturbed, they can panic and drop or abandon their young (Harriman and Shefferly 2003). Commercialization of caves has threatened the gray bat, as the increased human presence and disturbance in the cave can lead to the bats abandoning these caves (U.S. Fish & Wildlife Service Species Profile, n.d.). The gates used by officials to keep people out of caves can also harm bats by readjusting the caves temperature, humidity, and airflow (U.S. Fish & Wildlife Service 1997). These gates can also prevent bats from entering the cave. Disease may become a threat to the gray bat. Geomyces distructans, the fungus that causes White Nose Syndrome, has been found on gray bats but no mortality has been observed. The use of pesticides to kill insects can be a threat to bats because it limits food availability and can be toxic to bats. Other threats include the flooding of caves from man-made impoundments and natural flooding events. Wind farms are an emerging threat as new sites are developed within the range of the gray bat.
Conservation and Management
The gray bat is protected as an Endangered species by the Federal Endangered Species Act and as a Federally-designated Endangered species by Florida’s Endangered and Threatened Species Rule .
Federal Recovery Plan
Other Informative Links
Animal Diversity Web
Florida Natural Areas Inventory
International Union for Conservation of Nature
U.S. Army Corp of Engineers
U.S. Fish and Wildlife Service Species Profile
U.S. Fish and Wildlife Service Species Information
Printable version of this page
Florida Natural Areas Inventory. 2001. Field guide to the rare animals of Florida. http://www.fnai.org/FieldGuide/pdf/Myotis_grisescens.PDF
Harriman, V. and N. Shefferly. 2003. "Myotis grisescens" (On-line), Animal Diversity Web. Accessed May 31, 2011 http://animaldiversity.ummz.umich.edu/site/accounts/information/Myotis_grisescens.htm
U.S. Fish & Wildlife Service. (1997, September 18). Gray Bat: Myotis grisescens. Retrieved May 25, 2011, from Threatened and Endangered Species: http://www.fws.gov/Midwest/endangered/mammals/pdf/gray-bat.pdf
U.S. Fish & Wildlife Service. (n.d.). Gray Bat (Myotis grisescens) Species Information. Retrieved May 25, 2011, from Species Profile: http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A04J
Image Credit USFWS