Winter Home to Four Species

Crystal Cave is home to four species of bats during the winter. Bats are gentle, intelligent creatures that rarely interact with humans.

Bats are mammals. They are the only true flying mammal in the world. The wing of the bat is composed of the forearm and extended “fingers” of the hand. The third, fourth and fifth fingers support most the very thin wing membrane, a piece of delicate skin laced with veins. The thumb is seen as a tiny hook on top of the wing. The wing membrane connects with the body, hind limbs and, in most bats, encloses the tail.

There are over 900 species of bats found throughout the world. Wisconsin and Minnesota are home to seven species, all insect eaters. Three species spend only summer months in our area. The remaining four species are cave bats, are the most common, and remain here throughout the year. These bats are the little brown bat, big brown bat, eastern pipistrelle, and northern myotis. They are found in caves, abandoned mines, and buildings.

Cave bats range in size from three to five inches in length with wingspans of eight to thirteen inches. They weigh very little, from a tenth of an ounce to one-half an ounce. Bats can live to be twenty to thirty years old and usually have only one young, called a pup, each year. Because they are mammals, the baby bat is born alive and fed milk by the mother. The mother bat will nurse for about six weeks or until the pup can fly and catch insects on its own. Each female can locate her infant among thousands of others by sound and smell.

Cave bats feed at night, catching insects such as moths, flying beetles, and mosquitoes. They use ultrasonic sound, called echolocation, to locate their food. This echolocation involves emitting a high frequency sound which bounces off obstacles. Bats are able to hear these echoes and locate, identify, and capture moving prey while flying through the dark. Contrary to popular belief, bats are not blind. They see as well as humans and, if flying in the presence of light, will use their eyes rather than the echolocation.

Many people think bats are dirty, disease-carrying creatures. Again, this is largely based on false information. Bats are actually clean, relatively disease-free. People are most concerned with bats and rabies. This falsehood began more than forty years ago when erroneous testing procedures resulted in all bats testing positive for rabies. After additional testing, it was discovered that the bat carries a harmless virus that caused the same reaction as the rabies virus. Unfortunately, the damage was already done and this peaceful little creature was labeled as a menace to society. We must understand that because bats are mammals, there is the possibility of contracting the disease, but in this part of the United States, rabid bats are very rare. In any case, if a bat is on the ground you should assume it is sick. It should only be handled by a professional and sent to a lab to be examined for any diseases.

Bats are not an animal of which to be frightened. They will eat up to 300 insects each evening as they feed, ridding us of real unwanted pests. You should never disturb bats when you find them sleeping in caves or mines. Unless they become a nuisance, consider them as welcome guests! But remember, they are wild animals so never try to pet them or catch them for fun.