My Summer Bats

Bats have been of particular interest to me this summer as I’ve had great success with a “Rocket” style bat house. This box has been on a 10’ post in my yard for several years and seen only minimal success.

Most evenings my wife and I settle in to watch the bats emerge from the box which is situated in a clearing surrounded by trees. We’ve been able to count over one hundred several times. Only recently have I come to the conclusion they are the species, the Little Brown Bat, perhaps the most common, widely distributed in the U.S. They measure less than 4” in length and vary in color from olive-brown to a yellow-brown. The wings consist of naked skin, which are attached alongside the feet.

There are several bat species that are very similar in appearance, so we are still observing for more details and clues that will help definitively identify them.

During summer Little Browns often inhabit buildings, usually in hot environments like attics, where females form nursing colonies of hundreds or even thousands of individuals. Not much is known about where the males are at this time but they are likely solitary and scattered in a variety of roost situations. Colonies are often close to a lake or stream. This species seems to prefer to forage over water, but also forages among trees in open areas. Little Browns may repeat a set hunting pattern around houses or trees. Little Brown bats eat a variety of insects, including gnats, crane flies, beetles, wasps, and moths. Here is a very interesting thing I did not know about bats. Insects are usually captured with a wing tip, transferred into a scoop formed by the forwardly curled tail, and then grasped with the teeth. Because we don’t get to see them working in slow motion we would never see this action.

After doing a little more research on Southeastern bats, I learned some very interesting facts about these fascinating little nocturnal mammals. For instance, did you know that at certain times of the year we can have up to fifteen different species of bats in the southeastern United States? Or that all bats in the eastern United States feed exclusively on insects? They are the only major predator of night flying insects and may eat more than 50% of their body weight each night. Unfortunately, the amount of mosquitos they consume is not as great as once thought.

In late fall and winter the Little Brown Bat usually hibernates in caves and mines. Bats return from migration and awaken from hibernation as early as mid-March and they will be abundant throughout the summer and into early fall. By mid-October most will have migrated to more southerly states, or are going into hibernation. For more information about bats in our area please visit: the Tennessee Bat Working Group website.