Solitary eastern red bat seems to break all the rules

Now is the time when leaves fall and some birds head south. There is an often-overlooked warm-blooded migrant that benefits from the colorful autumnal leaves: the eastern red bat.

First, a quick bat review. No, they are not flying mice. They aren't even rodents. Bats belong to their own Order of mammals called Chiroptera.

And, no, they are not all rabid. In fact, rabies reports are often exaggerated. Between January 2008 through September 2017, according to the Centers for Disease Control and Prevention, there have only been 23 cases of rabies in humans in the U.S. and Puerto Rico.

Now, not all rabies viruses are the same. There are virus variants; some come from dogs or raccoons or bats. Only 11 of the 23 rabies variants came from bats. For the U.S., that's roughly one case of bat rabies per year over 10 years. I'll gladly take those odds.

Let's return to the eastern red bat. This bat has a one-foot wingspan and is 3.5 inches long. It can be found anywhere east of the Rockies as long as there are trees. Unlike many of their counterparts, red bats are usually solitary, only coming together to mate and migrate.

Most other local bat species have one young at a time. The rule-breaking red bats have an average of three young. While many other bats roost in a hollow tree, the red bat hangs from a twig, often in a shrub, as was the case with the red bat spotted last fall here at Stillman Nature Center.

Its fur was perfectly colored to look like a dried leaf. To further the effect, red bats will commonly hang from just one foot. After all, how many leaves have you seen with two stems?

Speaking of fur, few of our local bats have as much as the red bat. Fur coats the underside of the main wing bones as well as the top surface of the tail membrane. This probably is one of the reasons that bat we saw coped with the chilly October temperature it was roosting in.

Red bats can overwinter in temperatures that are well below freezing. They have the ability to increase their metabolism in order to keep their body temperature from falling too low.

A bat's metabolism is generally fueled by the insects it eats. Claims that bats will help reduce mosquito populations are often overstated. It is safe to say that bats eat thousands of mosquito-sized insects each night.

If you want to attract bats to your yard, there are numerous plans available online for small bat houses that can be mounted to a tree, garage, or the side of your house. These bat houses are more likely to attract species of brown bats rather than the red one.

The lasting image of that little red bat hanging from the shrub reminds me of the words of Josephine Winslow Johnson, “The dead elm leaves hung like folded bats.”

• Mark Spreyer is executive director of the Stillman Nature Center in Barrington. Email him at

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