Bats

Bats, like snakes, are poorly understood. As a result, these tiny winged mammals are feared by many. Much lore surrounding bats has been generated by tropical vampire bats which feed on the blood of livestock, wildlife, and occasionally sleeping humans. Of course, bats are a public health concern because they can carry rabies.

But species found in Minnesota are very small, weighing from two-tenths of an ounce to slightly over one ounce. Insectivorous, they feed mostly on flying insects, including beetles, moths, and mosquitoes which they catch in their cupped tail membranes as they dart and weave through the nighttime air. Once an insect is caught, the bat transfers its prey to its mouth while in flight.

Bats locate insects and dodge obstacles by echo-location. As they fly, they constantly emit supersonic cries. Their ears pick up echoes bouncing off objects. These echoes either guide bats toward prey or away from obstacles. Discovery of this unique principle led to development of sonar and radar by which boats and planes navigate, and fishermen locate schools of fish.

The little brown myotis, our most common bat species, occurs over most of North America. Together with the Northern myotis and big brown bat, it hibernates in Minnesota caves and mines. In summer, they roost in caves, mines, hollow trees, and buildings. Groups of these bats hang upside-down in caves. The Eastern pipistrelle is our smallest species, weighing only two-tenths of an ounce. It is found in the same Minnesota caves and mines, though it is uncommon and almost solitary.

The silver-haired bat is a forest dweller that usually lives near water. It feeds among the trees much like the Eastern red bat, though the latter is noted for its unusual feeding habits. Usually a red bat pair will fly the same route, over and over, in search of food. Another woodland species is the hoary bat. It is the largest Minnesota bat, weighing an ounce or more. All three species are solitary, roost in trees, and migrate south for the winter.

All seven bat species that occur in Minnesota may be found throughout the state.

What to do if you find bats in your house:

Q: Some homeowners have found a bat, or a number of bats, while remodeling rooms or making other home improvements during the winter. What should they do with the little winged creatures?

A: If the bat is awake and flying when first noticed, close doors to confine the bat in one room. Then, in that room, open the doors and windows to the outside and allow the bat to fly out of the building. It is best to do this at or after dusk. If this does not work, capture the bat (wear leather gloves to protect your hands) in a towel, or use a container such as a small trashcan or bowl to place over the bat when it lands. Take the container outside and shake the bat out onto a tree branch or surface from which it can fly away. Do not drop it onto the ground or into the snow, as it will have difficulty flying from such a cold, low spot. If the weather is severely cold, release the bat in a sheltered area or contact a local wildlife rehabilitator. View list of current wildlife rehabilitators.?

Read more about controlling unwanted bats.

- Lori Naumann, DNR nongame wildlife information officer