Rafinesque's Big-eared Bat (Corynorhinus rafinesquii)
- Texas Status
- Protection Status Notes
- Both subspecies are considered equally rare throughout their ranges. Population status has not been adequately monitored, but available evidence indicates that this species has declined alarmingly. Both subspecies, C. r. macrotis and C. r. rafinesquii, are considered species of special concern by the U.S. Fish and Wildlife Service.
- Corynorhinus rafinesquii is a medium-sized bat with long rabbit-like ears (27-37 mm). This bat has large facial glands protruding from each side of its snout. Its fur is grayish brown above and conspicuously bicolored underneath; each individual hair has a dark brown base and whitish tip. Its long toe hairs extend past the claws. It has a forearm length of 39-43 mm and weighs 7-13 g. The similar Townsend's big-eared bat lacks contrasting bicolored ventral fur and long toe hairs.
- Life History
- Their diet consists of mostly moths, but Rafinesque's Big-eared Bat will consume mosquitoes, beetles and flies as well. Predators that feed on the bat include snakes, raccoons, opossums, and cats. They reach sexual maturity at nine months. Mating season is in the fall. Adult females have one pup each year, born in late May or early June. The pups are able to fly three weeks after birth. They shed their milk teeth by mid-July, and reach adult size in about three months. They live up to ten years in the wild.
While other bat species are crepuscular (become active during twilight hours), Rafinesque's Big-eared Bats are nocturnal (become active when it is completely dark). Like others in the order Chioptera, these bats are insectivores (eat only insects). They also hibernate during the winter. When hibernating, the males and the females share sleeping quarters. During the late spring, however, pregnant females leave the males and nonreproductive females and establish nursery colonies to give birth and raise their young.
You've probably heard the expression "blind as a bat." This mistaken idea is probably due to the fact that bats rely on echolocation to find prey. Bats listen for the echoes of high frequency sound waves that they emit, bouncing off insects and other objects, to tell the size, shape and distance of the object. Echolocation helps them eat millions of insects every night. When Rafinesque's Big-eared Bats rest or hibernate, they coil their ears against their heads like rams' horns to reduce their ears' surface area and conserve body moisture. When disturbed, they unfold their ears.
Biologists age bats by looking at the finger bones in their outstretched wings over a bright light. Juvenile bats' bones have clear spaces between the joints; adult bats have ossified joints; they have turned to bone. Rafinesque's Big-eared Bats are also known as southeastern big-eared bats, eastern big-eared bats, eastern lump-nosed bats and eastern long-eared bats.
- Rafinesque's Big-eared Bats roost in cave entrances, hollow trees, abandoned buildings and under bridges in the forests of southeastern United States.
- Rafinesque's big-eared bat is also known as the southeastern big-eared bat, which aptly describes where it lives in the United States. The subspecies C. r. macrotis is found along the Gulf Coast, from Texas to Florida and north to Virginia. Its inland counterpart, C. r. rafinesquii, occupies the northern part of the species' range including eastern Arkansas and Missouri north to eastern Illinois, southern Indiana, all of Kentucky, and Tennessee, to western West Virginia.
In the southeastern United States they reach the westernmost portion of their range in the pine forests of East Texas.
- Threats and Reasons for Decline
- Most Rafinesque's big-eared bats originally required large hollow trees. Throughout their range, many such roosts have been lost. The relatively few remaining colonies now survive mostly in lowland tree hollows that are subject to flooding, or in abandoned buildings that are prone to human disturbance and structural collapse from decay. Some occupy cave entrances and rock shelters, again where they are easily disturbed.
- Ongoing Recovery
- Protection of large hollow trees in lowland areas, especially near water sources, is essential to the preservation of this species. Artificial roosts may be required to provide crucial alternatives in areas where hollow trees and abandoned buildings have been removed.
- Rafinesque's Big-eared Bats are one of the least known bats in the southeastern United States. Like all bats, big-eared bats help make our lives more comfortable by eating millions of bugs, especially mosquitoes, every night. This bat uses its big ears and echolocation to help it find food. Because Rafinesque's Big-eared Bats feed on insects that can be harmful to agriculture, people should treasure this animal. However, their numbers seem to be declining and they have been listed as threatened since 1977. As people learn more about the role bats play in managing insect populations, perhaps they will understand the importance of protecting bat roosts.
Like all mammals, bats can contract rabies, but they are no more susceptible to the disease than raccoons, skunks or even dogs. Just like other animals, bats will bite if they feel threatened. If you find a bat on the ground (rabies immobilizes the animal sometimes), don't try to help it. Leave it alone and call a game warden. The warden will be able to take care of the animal appropriately.
Roost temperature requirements for maternity colonies, as well as hibernating groups, are poorly understood. Most remaining colonies live in old buildings that soon may be lost. More detailed knowledge of roost requirements is essential in order to provide artificial roosts. Feeding habitat requirements also remain poorly documented.
For more information
- Additional details can be found in the online version of The Mammals of Texas for the Rafinesque's Big-eared Bat