Missouri Cave Bats

Talk about cave life, and what do you hear about? Bats! Here are a few facts about Missouri cave bats. Bats are mammals, and members of the order Chiroptera. They are the second largest order of mammals in number of species, (second only to rodents.) There are about 1000 species of bats, 14 of which live in Missouri. Of these, 9 are commonly found in caves.

Except for the Big Brown Bat Eptesicus fuscus, the Eastern Pippistrelle, Pippistrellus subflavus, occasional specimens of Mexican Free-tail Bats,Tadarida brasiliensis, and possible extremely rare subspecies populations of Townsend's Big Eared Bats called the Ozark Big-Eared Bat, Corynorhinus townsendii ingens, most Missouri cave bats are bats of the genus Myotis, or mouse-eared bats.

Eastern Pippistrelle

The Eastern Pippistrelle is the smallest cave dwelling bat. It is easily recognizable by its pink arm bones, and small size (usually less than 1/3 oz. in weight.) Pippistrelles are solitary sleepers, and can easily go through openings with a diameter of less than a dime. They live in caves year round. Little Brown Bats are one of the most common myotine species in the state. They have dark arm bones, and often sleep near each other, though not piled together in clumps as do the endangered species.

Big Brown Bat

Big Brown Bats often roost near the entrances of caves. They have a body length from head to tail of about 3 inches, and are recognizable by their shiny brown hair, which resembles that of a chihuahua dog.

Bat Colony--MDC photo by Rick Clawson

Gray and Indiana Bats are federally listed as endangered, even though they may appear to be locally plentiful. The exclusive use of a very few caves by large populations as hibernacula by both, and by grays as maternity colonies, make them very vulnerable to disturbance by humans. They have no place else to go for the birthing process, or the winter. Cave gating has been successful in helping gray bat colonies to recover, but Indiana bat numbers keep dropping. Since Indiana bats spend summer days in shaggy-barked bottomland forests, some people believe urbanization and other forest disturbance may play a role in the Indiana bat numbers loss.

It is often difficult to sort out myotine species by sight alone. Color does not distinguish one type of bat from another. Colonial bats in caves in the summer are usually grays, but both females and males use the caves as summer roosts. It takes an expert at bat identification, who has been trained to handle the animals to note the minor differences in physical characteristics to distinguish them. NO ONE untrained to handle bats should attempt to pick one up. Even the experts use leather gloves. If a bat is on the floor, it is probably ill or injured.

Of all the bats suspected of rabies and taken to health officials, less than one half of 1% test positive. The rabies rates for wild racoons, squirrels, and deer is much higher. Tropical bat species may have a higher rate of rabies infection than temperate species. A much higher risk of exposure to disease harbored by bats is that of contracting histoplasmosis, a fungal spore which invades the lungs, and for which there is no treatment except to keep down the secondary infections. Histoplasmosis is present in dry bat guano, as well as dry bird droppings, such as in a chicken coop.

The Secret Life of Bats

All Missouri bats are insect eaters. A gray bat can consume up to 6000 insects a night. High on the food list for Missouri bats are moths, mosquitoes, and other night flying insects. Bat guano, or droppings, is very useful stuff. Guano forms the base of the food chain in many caves, utilized by micro-organisms and invertebrates, which become food for salamanders frogs, and other larger animals. Bat guano has also been used for fertilizer, and in cosmetics.

Bats have odd sex lives. Even though mating takes place in the fall, conception does not occur until spring. Males do not take care of the young. A baby bat, weighing between 1/10th and 1/3 as much as the mother, is born in May or June, and learns to fly and catch its own food in about 6 weeks.

Many people know about a bat's ability to echolocate, or find its way in the dark by using ultrasonic wave, which it emits, then "hears." But not many people know that bats have voices-- squeaks and hisses audible to humans. Because of these differing ranges of hearing, people should avoid whispering around bats, or making metallic sounds, such as jingling keys. Both emit frequencies which are quite distracting to bats.

Indiana Bats helped to save the Meramec River from an Army Corps of Engineers dam project in the early 1970's. Because the federally endangered bats occupied caves along the river's corridor, the project was delayed until the impact of the lake project on the bats could be determined. In the meantime, other human forces came together, which caused the proposed construction to be put to a vote, and defeated in a referendum, August of 1978.

Cavers and other humans in caves disturb bats, mostly because people go into caves while them bats are sleeping. This is an annoyance to adult bats in the summer, but can be fatal to baby bats, still too young to fend for themselves. If a bat is dropped by the mother, it generally cannot be retrieved from the floor, and dies.

In the winter, bats attempt to survive the winter by living on stored fat reserves. Disturbance rouses the bats, causing them to burn precious fat. Let sleeping bats sleep. If you must look, use only red, or dimmed electric lights and talk in low tones (not whispers). The heat from carbide lamps will also rouse bats unnecessarily.

For more information on bats see Bat Conservation International, at Bat Conservation International.

For more information on cave biology, visit Bill Elliott's Biospeleology Webpage.

2003 Jo Schaper.

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