I was walking at sunset in coastal Connecticut in early November and was surprised by something I saw. What I thought at first was a bird was actually a bat. It was flying pretty high up and heading south. What struck me was its color—it had bright, brick-red fur. Smaller than a Big Brown Bat (Eptesicus fuscus), at about 4 inches (10 centimeters) from head to tail, it was instead an Eastern Red Bat (Lasiurus borealis), a migratory species. The Eastern Red Bat is one of three tree-roosting bat species in Connecticut. The others are the Silver-haired Bat (Lasionycteris noctivagans) and the Hoary Bat (Lasiurus cinereus). These species are also migratory.
Eastern Red Bats migrate to the southern United States. A study done in Arkansas showed that Eastern Red Bats remain active through the winter, but when temperatures plunge they will often seek shelter under leaf litter. Those that do are better protected from cold than those that roost in trees. But there is a trade-off. Sheltering in leaf litter makes bats more vulnerable to predators, such as the Virginia Opossum (Didelphis virginiana).
Not all bats migrate south. Six species migrate regionally: the Big Brown, Little Brown Bat (Myotis lucifugus), Indiana Bat (Myotis sodalis), Tri-colored Bat (Perimyotis subflavus), Northern Long-eared Bat (Myotis septentrionalis), and the Eastern Small-footed Bat (Myotis leibii). They go to cavernous places like caves, mines, and other underground structures where the temperature doesn’t fluctuate much and stays between 32°F (0°C) and 49°F (9.4°C).
The Little Brown Bat, like most cave-dwelling species, is one of Connecticut’s true hibernators. It eats lots of insects to fatten up for the winter. Then its deep, core body temperature drops to between 35°F (1.6°C) and 40°F (4.4°C). If it wakes up, even for only a few minutes, it would burn off all its fat stores it needs for the rest of the winter, and die.
All is not well with cavern-dwelling bat species. In 2006, a fungus from Europe was introduced into a cave in upstate New York, probably on the gear or footwear of a visitor. The disease it causes is called White Nose Syndrome. The fungus is Pseudogymnoascus destructans, or Pd, which likes the same cool, humid conditions in caves that hibernating bats do. Pd attacks the bat’s muzzle and wings. The irritation wakes the bat and so it uses up its valuable fat stores. Some bats will even go outside in midwinter to find food. Like most invasive species, in its native locations the fungus doesn’t harm European bats. But our native bats have not evolved with Pd and are harmed by it. Little Brown Bat populations, once the most common species in the U.S. Northeast, have declined by more than 90%. All cavern-dwelling bats except the Big Brown Bat are now endangered. For some reason the Big Brown Bat doesn’t seem to be as susceptible to this fungus.
Bats need our help. Learning more about these gentle creatures is a first step to allaying fears caused by Dracula movies and cultural myths. Apocryphal tales, like stories of bats flying into a person’s hair, probably arose from someone seeing a bat swoop down nearby to grab a mosquito. Bats are not flying rodents. They are more closely related to us than they are to mice or voles. Bats are not blind. They have good eyesight, but use echolocation (reflected sound) to navigate in the dark. Like many mammals, bats can carry rabies, but only half of one percent of the population has the virus. To contract rabies, you would need to be bitten or scratched by a bat that is infected. More people die from dog attacks and lightning strikes than from bat-transmitted rabies.
As the only mammals capable of true, sustained flight, bats are remarkable. They’re remarkable in other ways too. Do you live near water and are bothered by mosquitoes? An individual Little Brown Bat has been documented eating more than 1,000 mosquitoes and other insects in an hour! You can help bats (and yourself!) by installing a bat house as a home for a bat maternity colony next summer. Now is a good time to buy or make a bat house. A house placed 20 to 30 feet (6 to 9 meters) above the ground in a sunny location and with an open flight path to it is most successful. Bats are more likely to use houses placed on the side of a house or on a pole than on a tree.
Have you seen a bat in Connecticut out flying in the winter or roosting in summer in your bat house, barn, or eaves? Have you seen a dead bat? The Connecticut Department of Energy and Environmental Protection’s Wildlife Division would like to hear about it. Use its Public Bat Sightings Form to report your observations. Let’s all do our part to help ensure these amazing creatures survive into the future.