Thursday, October 9, 2008 9:55 PM CDT
Halloween approaches, but don’t be afraid of bats
By ESTHER LUTZ
Leaves are turning, and darkness comes earlier now. Woolly worms are forecasting winter with their furry coats, and we’re seeing lots of squirrels with acorn-stuffed mouths bounding across the streets. October is in full swing, and you know what that means: there’s a ghoulish holiday looming on the calendar. Along with it comes many disturbing creatures, some legendary and some very real. But when the flying ones venture out only in the blackness of night, their reputation takes on an eerie and almost mythical quality.
Over the years, people in many cultures have been fearful of bats. Hollywood and the movies have connected them with Count Dracula, vampires and Halloween, but they truly are not the frightening creatures that they have been portrayed to be. In Illinois, bats are voracious predators of night-flying insects and are ecologically important in helping to keep insect crop and forest pest populations under control.
Bats in Illinois are all small, winged mammals whose heads and bodies are covered with fur. Their forelimbs are extremely modified to form wings that are very different from those of birds. The fingers are greatly lengthened to support a thin membrane that extends over them, with a clawed thumb that remains free. Another membrane connects the small hind legs to the tail. Because of these specialized structures, bats are the only mammal capable of real flight. It is a fact that flying squirrels can glide, but only bats can truly fly.
There are 12 species of bats that occur regularly in Illinois, and all are insectivorous (insect-eaters), most weighing less than one ounce each. Like all mammals, bats bear live young (called pups) which are nursed by their mother and cling to her when first born. A female gives birth usually in May or June to one or two pups, sometimes three to five, depending on the species. The gestation period is about 60 days. Bats do not build nests, but some species will form groups of females (maternal colonies) that roost beneath loose tree bark, in hollow trees, in abandoned buildings or attics, or in caves. When the mother feeds at night, the young bats are left at the roost site but will fly out and start feeding on insects after about three weeks. Even so, they will continue to nurse until they’re about a month-and-a-half old.
A single bat may consume an estimated 3,000 insects in one night and lactating females even more. They begin hunting at dusk and may return to the roost to rest or nurse their pups after a couple of hours. Feeding during flight may continue intermittently through the night with the final excursion occurring around dawn. During the day, bats roost (rest) in a protected area away from weather and predators by hanging upside down, a position that allows for a fast takeoff.
Because some species have limited eyesight, their large ears form part of a unique system for locating and avoiding objects in flight. The Illinois bat species rely on echolocation, a series of ultrasonic sound pulses emitted by its mouth and larynx as it flies. Once the sound makes contact with an object, an echo is bounced back and is received by the bat’s ears. Using the strength of the echoes it can then determine the location and shape of an object and its distance away, forming an acoustic image in its brain much like the sonar of a submarine. Slight differences in the echo’s delay help reveal the object’s direction and size. The creature uses this information to find its way in the dark, to avoid obstacles in its flight path and to track down prey. These sounds that bats emit are at such high frequency that they cannot be heard by humans.
Bats have many predators, including raccoons, skunks, minks, cats, hawks, owls and snakes. Humans pose a threat, also, by destroying colonies in buildings or disturbing hibernating bats in caves. Since they have limited reserves of fat to carry them through the winter, if they are disturbed during hibernation and fly around, they might not have enough energy to survive until spring when insects become plentiful again. Bats have been recorded to live as long as 30 years in the wild despite the dangers, but the average life span is closer to four to six years.
Do bats ever attack humans and get caught or nest in your hair? Like most wild creatures, bats try to avoid human contact. They are small and gentle animals, and healthy bats will not attack people. Remember that we are very large to a bat, and they’re afraid of us. They may bite as a defense if handled, so try to avoid holding them. Like all mammals, they can contract rabies, but your chance of coming in contact with a rabid bat is very rare. Even so, if you find a bat, you should contact the authorities and leave it alone. Because its echolocation abilities are so precise, chances are also slight that one would make a mistake and get tangled in your hair. It roosts, and therefore won’t make nests in hair or anything else.
If a bat flies into your house, what should you do? The biggest problem for bats is the shortage of naturally occurring places to live. As a result, some bat species may take up residence in human dwellings. If one ever gets in and starts flying around, don’t panic. It may make sharp turns while flying and appear to swoop down at you, but it is not attempting to attack. It is simply trying to get its bearings so it can find its way outside. If it has not bitten anyone, simply turn down the lights and open a door or window. Close the door to keep it confined and leave the room. It may take a while, but it will usually find its way out. If you suspect it has bitten a person or pet, it will need to be captured and sent off to be tested for rabies. Contact the local animal control authorities. Bat bites are small and we may not know if a bite has occurred (especially when sleeping), so it’s best to err on the side of caution. If the test comes back positive, then medical attention is needed.
Despite educational efforts, many fears and myths still exist about bats. Night creatures are traditionally mysterious, and a bat is as at home in the darkness as a fish is in water. It beams its voice around like a flashlight, and the echoes come singing back. In the early evening, grab a jacket, go outside and listen. You may hear owls hooting or the last frogs croaking, or smell autumn in the air. But don’t forget to look upward toward the moon on these crisp nights — you may even see a bat fly overhead.
Esther Lutz is East Central Illinois Master Naturalist for University of Illinois Extension in Coles County.
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