Rafinesque's Big-eared Bat

RAFINESQUE’S BIG-EARED BAT

Photo Credit: Merlin D. Tuttle, Bat Conservation International

SCIENTIFIC NAME: Corynorhinus rafinesquii (Lesson)

OTHER NAMES: None.

DESCRIPTION: A mid-sized (total length, 85-105 mm [3.4-4.2 in.]; weight, 8-10 g [0.28-0.35 oz.]; females may weigh up to 14 g [0.50 oz.]) bat distinguished from all other bats that occur in Alabama by large ears (27-37 mm [1.0-1.5 in.] long). Dorsum brownish gray overall, individual hairs are dark brown to blackish basally, pale reddish to brownish distally; venter is whitish (Handley 1959; Jones 1977; Choate et al. 1994). Two subspecies occur in Alabama; generally, C. r. rafinesquii is found north of the Tennessee River and C. r. macrotis south (Hall 1981a).

DISTRIBUTION: From central Illinois and Indiana south to the Gulf of Mexico and from eastern Oklahoma and Texas to the Atlantic Ocean. Previous records indicate potentially occurs throughout Alabama (Handley 1959, Hall 1981a, Choate et al. 1994, Harvey et al. 1999).

HABITAT: A variety of forested habitats from tupelo gum-bald cypress swamps near Mobile Bay to pine-deciduous forests of northern Alabama (T. L. Best, pers. observ.). Maternity colonies and summer roost sites often partially lighted, and include unoccupied buildings and other human-made structures. Also use caves, trees, and other natural places as roost sites. Hibernacula include caves, mines, cisterns, and wells (Jones and Suttkus 1975, Jones 1977, Choate et al. 1994).

LIFE HISTORY AND ECOLOGY: One young born in late May or early June. At birth, hairless young weigh about 2.5 grams (0.1 ounce). Young are closely associated with their mothers for about three weeks after birth, when they obtain permanent dentition and begin to fly. At about 15-18 days of age, young are capable of straight-line, nonagile flight. Mothers disturbed at the colony will fly with their young attached, but there is no evidence that young are carried by adults when foraging. Young reach adult weight in about four weeks after birth. Life span is at least eight to 10 years. Colonies range in size from few to about 100 individuals in some parts of geographic distribution, but at present, the largest known colony in Alabama contains one to three of these bats. Roost singly and in clusters. Although there is a tendency to use the same locations within roosts, they often move among locations within a roost site in response to changes in temperature; this occurs in summer and winter. In summer, individuals usually are active at the roost and are capable of immediate flight. When disturbed, they move their ears and often turn the head to look about. In winter, and sometimes in summer, they hang with ears coiled alongside the head; usually, ears are between the head and folded wings. When disturbed in this position during rest or torpor, it may take several minutes for them to arouse and erect the ears. Hibernate, but duration unknown. Emerge from day roosts late in evening to forage; apparently, do not forage at twilight. Diet composed of moths and other night-flying insects. Potential predators include snakes, raccoons, opossums, and domestic cats. Because of roosting habits, highly susceptible to predation and disturbance by humans (Jones and Suttkus 1975, Jones 1977, Choate et al. 1994, Harvey et al. 1999).

BASIS FOR STATUS CLASSIFICATION: One of the least known of all bats in the southeastern United States. Little is known about its population trends and ecological requirements. Uncommon over most of its distribution, including Alabama.

Author: Troy L. Best


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