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.
Five species of myotine bats are known from Missouri:
Little Brown Bat--Myotis lucifugus
Gray Bat--Myotis grisesecens
Indiana Bat--Myotis sodalis
Small Footed Bat--Myotis leibii
and the Northern Long-Eared Bat--Myotis septentrionalis
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.
2003 Jo Schaper.