The Ozark big-eared bat, (Corynorhinus townsendii ingens) can be found in limited numbers in the southern central U.S. Although these bats were once found in Missouri, Arkansas, Oklahoma, they are no longer in Missouri due to destruction of the surrounding environment and disturbance of their caves. In Oklahoma they are found in Adair County and adjacent parts of Cherokee and Delaware counties. The habitat for the Ozark Big-eared Bats are limestone caves in wooded areas of the Ozark Highlands. The associated biome is temperate deciduous forest. They are not migratory and usually prefer oak and oak-hickory woodlands. This bat can be identified by its enormous ears that practically dwarf the face and its lump-like nose. Other names for this endangered species include the long-eared bat, the lump-nosed bat and the western big-eared bat. The bats will not be seen in winter months because they hybernate (U.S. Fish and Wildlife Service, 1995).
Life Cycle of the Species
Maternity colonies can be found in cooler temperature caves that remain at about 55 degrees Fahrenheit. These bats have a high pitched mating call that signals when a female is prepared to mate. Mating occurs in the fall and the female stores the sperm until after hibernation when there is enough nutrition to support pregnancy. Gestation lasts about two months and young bats are born live like other mammals. Only one offspring is produced per pregnancy and many don’t survive due to disease and human interference in their habitats. These factors also contribute to their low numbers. The young bat grow quite fast and can fly by the time they are three weeks old. By six weeks old they are fully weaned from their mothers and must now hunt for food which consists primarily of moths and other insects with the rest of the adult population.
Structure and Function of the Ozark Big Eared Bats Echolocation System
Like other bats, the Ozark Big Eared Bat has special sensory organs that allow it to locate prey without seeing them. The bat sends out a high pitched sound which is too high for humans to hear and the sound waves bounce off of solid structures. The waves return to the bat who uses it’s sensory organs to determine whether the object is food (i.e. an insect) or other. When it determines it is an insect it can filter out all other signals, focus on that particular signal and quickly locate, fly to and consume the bug. Although the bat is small, it consumes a \large number of insects each night meaning that the sensory organs responding to the sound waves have to be very advanced. In addition, Ozark bats hunt later in the night than most other bats such that they must be able to use their echolocation abilities not just to locate pray but to avoid trees and other obstacles as well as other bats who are also out hunting.
Unique Evolutionary Characteristics
Bats are the only group of mammals who have developed true, self-powered flight. In order to achieve this they developed modified forelimbs which are capable of supporting the wing membranes (patagium). While the bats limbs resemble other mammalian limbs there are different bone to muscle ratios in the bat compared to non-flying mammals. The hands and fingers are the most lengthened structures of the limb. These bones are the primary supports for the wing membranes and allow the bat to control its flight. The wing membrane extends across the bats fingers and is affixed to the side or back and the lower portion of the leg. Part of the patagium stretches between the posterior limbs. There are many blood vessels and nerves found throughout the patagium.. To give them the strength to fly, Bats have also developed five unique muscles within the wing membrane. They also use other chest and back muscles to enable them to move their wings at a high speed to maintain flight
Evolutionary differences between birds and bats are evident on sight. The clearest factor which differentiates bat wings and bird wings is that bats wings are composed entirely of membrane while bird wings are composed of feathers. While birds have a lengthened arm to help support their wings they do not have lengthened fingers because they are not necessary for their wing structure. Another difference is that the muscles used to power the wings in birds are found exclusively in their chests while for bats these muscles are found along their backs. (Fenton, 1983).
The way the rear limbs are oriented also help support the wing membrane. They are rotated 90 degrees from the hip such that the knees are turned backwards causing an awkward walking motion. However, this adaptation provides enormous benefits in helping support the large wing membranes and in allowing the bat to hang upside down with special tendons that lock the claws into place to allow the bat to sleep in this position.
References
Arkansas Game and Fish Commission Strategic Non-game Management Plan.(n.d.). Prepared
Currie, R. (2000). Federally listed threatened and endangered species of concern to mining.
Paper presented at Bat Conservation and Mining: A Technical and Interactive Forum, November 14-16, St. Louis, MO.
Fenton, M. B. (1983). Just Bats. Toronto: University of Toronto Press.
U.S. Fish and Wildlife Service (1995). Ozark Big-Eared Bat Corynorhinus townsendii ingens
(Handley) Revised Recovery Plan. Tulsa, OK.
