Bats

Bats are the only mammals that truly fly.  Their forelimbs have evolved to become wings.  Bat bodies are generally well furred, but wing membranes are often naked and transparent.  Unlike birds, which flap their wings up and down, bats "swim" through the air.  Some species fly with the agility of swifts and occassionally hunt with such birds at dusk.  Wing beats may be as rapid as 20 persecond.  With wings folded, bats can walk or climb, and some can swing from branch to branch.  At rest, they hang head downward, sometimes by one hindfoot, using the other to groom their fur and clean their teeth. 

Most bats have small eyes and relatively poor vision; hence the phrase "blind as a bat".  However, they do not bump into things and can zero in on the tiniest insects by means of echolocation, similar to sonar.   While flying, the bat emits through its nose or slightly opened mouth a continuous series of supersonic sounds (about 30 to 60 squeaks per second) that bounce off objects and are picked up by the bat's complex ears.  From the way the sounds are interpreted, the bat determines size, locaion, density, and movement of the object it approaches.

Bats are nocturnal animals that leave their daytime roosts about dusk and usually fly to a stream, pond, or lake where they dip their lower jaws into the water to drink.  They then catch insects in their mouths, or scoop them into their wings.  Bats may feed as they fly, turning a somersault as they extract food from the wing membrane, or, it their meal is too large, alight to dine. Bats eat hundreds of thousands of insects annually. The myth that bats fly into people's hair is based on the fact that they often fly very close to animals, including humans, seeking the insects that sometimes swarm about their heads.

Vespertilionid bats - Family Vespertilionidae

Little Brown Myotis Myotis lucifugus. Found statewide; although common throughout its distribution, is rare in Alabama with no breeding colonies known. Elsewhere in distribution, groups of several thousand females form maternity colonies in buildings. Mating occurs before hibernation, but copulating pairs may be found in hibernacula throughout winter. In spring, a single young is born. Lifespans of greater than 30 years documented in wild. Diet includes a variety of insects, including flies, moths, and small beetles. HIGH CONSERVATION CONCERN.

Southeastern Myotis Myotis austroriparius. Occurs in southern half and western half of Alabama, but may be most common in southern tier of counties. Active year-round, it occupies caves, mines, and buildings, but may go into torpor for a few days when daily temperatures approach freezing. Only one maternity colony known in Alabama. Twins are born in spring and become volant in five to six weeks. HIGH CONSERVATION CONCERN.

Gray Myotis Myotis grisescens. Found statewide, except for southwestern quarter. Occupies deep caves near permanent water in winter and summer. Breeds in autumn before hibernation, but mating probably occurs in winter. One young born in June becomes volant in 20-25 days. Forages primarily over water, along streams, and over lakes and ponds. Consumes a variety of small insects, including moths and mayflies. Lifespan may exceed 15 years. Listed as endangered by the U.S. Fish and Wildlife Service. HIGHEST CONSERVATION CONCERN.

Northern Long-eared Myotis Myotis septentrionalis. Poorly known. Found statewide, except southwestern region. Forested ridges appear favored over riparian woodlands. Hibernacula include caves and mines, but may use crevices in walls or ceilings. Summer roosts include tree holes, birdhouses, or behind loose bark or shutters of buildings. One young born in late spring or early summer weaned about a month after birth. HIGH CONSERVATION CONCERN.

Small-footed Myotis Myotis leibii. Probably occurs in northeastern Alabama because is known from adjacent areas of Tennessee and Georgia. Distribution maps often depict it occurring in Alabama, but no specimens known from state. MODERATE CONSERVATION CONCERN.

Indiana Myotis Myotis sodalis. Rare. Occurs in northern and eastern half of Alabama, but populations continue to decline distribution wide.  Hibernates in caves, mostly in tight clusters. In summer, females form small maternity colonies in tree hollows and behind loose bark. A single offspring born in June or early July is weaned in 25-35 days. Diet includes small, soft-bodied insects, such as moths, flies, and beetles. Listed as endangered by the U.S. Fish and Wildlife Service. HIGHEST CONSERVATION CONCERN.

Silver-haired Bat Lasionycteris noctivagans. Poorly known. Probably found statewide, except for southern tier of counties. Little known of distribution and habits in Alabama. Probably present as a winter resident, or in spring and autumn migration, but apparently not in summer. In winter, hibernates in a variety of shelters, including buildings, caves, mines, crevices, and hollow trees. Not known to breed in Alabama. MODERATE CONSERVATION CONCERN.

Eastern Pipistrelle Perimyotis subflavus. Found statewide and common. Occupies hollow trees, tree foliage, caves, mines, rock crevices, and buildings. Hibernates in winter, often with beads of water forming on fur from humid surroundings. In late May through early July, an average of two young are born. Diet includes a variety of insects, including leafhoppers, beetles, and flies. Lowest Conservation Concern.

Big Brown Bat Eptesicus fuscus. Found statewide and common. Roosts typically in human-made structures, but also in caves, mines, hollow trees, and crevices, or behind loose bark. Commonly inhabits bat houses, attics, and louvered attic vents. Copulates in autumn and winter, ovulation occurs in spring, and two young are born in late spring. Diet consists primarily of beetles, but flies, moths, bugs, and cicadellids also consumed. Lowest Conservation Concern.

Eastern Red Bat Lasiurus borealis. Found statewide and common. Roosts in a variety of trees, but frequently uses clumps of Spanish moss. Often emerges early, while sun is in the western sky. Breeding may take place during southward migration in autumn, and copulation in flight has been observed. An average of four young are born in spring. Lowest Conservation concern.

Seminole Bat Lasiurus seminolus. Found statewide. Common in mixed coniferous and deciduous woodlands; often associated with Spanish moss. Parturition occurs late-May and early June, with two to four young born. Mostly forages at treetop level in forests, although also flies over open water, forest clearings, and along forest edges. Diet consists of flies, beetles, dragonflies, and hymenopterans. Lowest Conservation concern.

Hoary Bat Lasiurus cinereus. Poorly known. Found statewide, but are few records of this large (avg. 25 g [1 oz.]) species in Alabama. Roosts in trees or shrubs, usually three to five meters (9-15 feet) above ground. Females bear two young in late spring. Migratory and may not breed in state, but some females may raise young here. MODERATE CONSERVATION CONCERN.

Northern Yellow Bat Lasiurus intermedius. Rare and poorly known. Only a few records from the southern tier of counties. This relatively large (14-31 g [0.5-1.1 oz.]) bat inhabits coniferous and deciduous woodlands near permanent water. Often roosts in clumps of Spanish moss, but also in trees. Breeds in autumn and winter; two to four young born in spring. Diet consists of flies, bugs, dragonflies, beetles, and hymenopterans. HIGH CONSERVATION CONCERN.

Evening Bat Nycticeius humeralis. Found statewide, but may be most common in southern half. Primary habitat is deciduous forest where it roosts in hollow trees, under loose bark, and in human-made structures, such as outbuildings, churches, belfries, and attics. One to three young (usually two) born in early June. Diet consists of a variety of insects, including moths, beetles, flies, bugs, and flying ants. Lowest Conservation Concern.

Rafinesque’s Big-eared Bat Corynorhinus rafinesquii. Poorly known. Found statewide, but among least-known bats in region. In summer, roost sites may be behind loose bark, in caves, crevices, and hollow trees, and in unoccupied buildings, abandoned mines and wells, and other human-made structures. In winter, may hibernate briefly in open and well-lighted hibernacula. Mating occurs in autumn and winter; one young born in late spring. Diet primarily moths.  HIGHEST CONSERVATION CONCERN.

Free-tailed Bats - Family Molossidae

Brazilian Free-tailed Bat Tadarida brasiliensis. Poorly known. Possibly found statewide, but most remaining populations are in southern half. Occurs only in human-made structures. Essentially nonmigratory and does not hibernate, but summer and winter roosts may be in different localities. Breeds in March, gestation is 11-12 weeks, and one young born in June. Diet primarily moths. HIGH CONSERVATION CONCERN.

References Cited:

Mirarchi. Ralph E., ed. 2004. Alabama Wildlife, Volume One.  A Checklist of Vertebrates and Selected Invertebrates: Aquatic Mollusks, Fishes, Amphibians, Reptiles, Birds and Mammals.  The University of Alabama Press, Tuscaloosa, AL. 209 pp.

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