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Ozark Big-eared Bat
Corynorhinus townsendii ingens
Family: Vespertilionidae
Description: The Ozark big-eared bat is the largest and reddest of the five subspecies of Corynorhinus townsendii. The species is medium-sized and weighs from 0.2-0.4 ounces (5-13 grams). It has very large (1 inch; 2.5 cm) ears that connect at the base across the forehead. The snout has prominent lumps. The Ozark big-eared bat closely resembles the eastern big-eared bat, but has tan instead of white underparts and brown instead of gray dorsal hair.
| Status: |
Federally Listed Endangered (November 30, 1979) Global Rank: G4T1 State Rank: S1 |
Distribution: The Ozark big-eared bat historically occurred in the Ozark Mountain regions of northeastern Oklahoma, northwestern Arkansas, and southwestern Missouri. The subspecies is believed to have been extirpated from Missouri. Arkansas and Oklahoma still possess extant populations of this bat. In Arkansas, the Ozark big-eared bat is known only from Marion and Washington Counties.
Habitat: The Ozark big-eared bat inhabits karst regions dominated by mature hardwood forests. This bat is one of many karst-dependent species in northern Arkansas. Karst habitats form in regions with limestone bedrock. Over thousands of years, water seeping into the ground dissolves limestone and forms sinkholes, underground streams, and caves.
The Ozark big-eared bat utilizes caves year-round as roost sites. During the winter, most populations hibernate in a few cold caves that provide optimum temperatures for hibernation. During the summer, females congregate in warm maternity caves to raise their young. Hibernation cave temperatures usually range from 40-50°F (4-9°C). while maternity colonies are found in caves with temperatures from 50-59°F (10-15°C). Migration distances between hibernation and summer caves range from four to 40 miles (6.5-65 km).
Diet: Ozark big-eared bats are moth-specialists, with night-flying Lepidoptera making up the bulk of their diet. Most foraging generally takes place along forest edges.
Reproduction: Big-eared bats mate in the fall and females store sperm over the winter. Pregnancy occurs in the spring at the end of hibernation. Ozark big-eared bats give birth to a single offspring. Young bats grow quite rapidly and are capable of flight at three weeks and are weaned by six weeks. Males apparently disperse into smaller groups separate from the females during the summer.
Conservation Status: The primary factor contributing to the decline of the Ozark big-eared bat is disturbance and vandalism at cave and roost sites. Disturbance during hibernation results in an increased use of stored fat reserves and, if intense or frequent enough, can result in direct or indirect mortality. Disturbance at maternity sites can result in direct mortality of the young or the movement of maternity colonies from optimum to marginal summer roost sites.
It has been estimated that only about 1,700 Ozark big-eared bats remain, with the majority of these (1,400) occurring in Oklahoma. A number of Arkansas caves used by the Ozark big-eared bat are now protected by the Arkansas Natural Heritage Commission and The Nature Conservancy. Currently, a multi-partner effort involving the U.S. Fish and Wildlife Service, Arkansas Natural Heritage Commission, Arkansas Game and Fish Commission, and The Nature Conservancy is working toward protecting more land for this species in Oklahoma and Arkansas.
