I returned home one evening recently to find my wife, Sue, obviously disturbed. She was glad to see me, so at least I wasn’t in trouble. She advised that there was a bat in the sink in the basement bathroom and was most anxious that I remove it. She had covered the sink with a large bowl, but the bowl didn’t fit very well. She covered the gaps with some old towels. I put on a pair of gloves and gently lifted the towels and bowl only to find the reported bat missing. I began to think that Sue might have been hallucinating after I had looked high and low all through our finished basement and could find no bat. It was getting late, so I closed the door to the basement and we retired.
I thought I’d look again the next evening and still wasn’t having much luck. The door into the basement bathroom opens against a wall, leaving a relatively small space between the door and the wall. I’d looked there before, but had failed to notice a small dark lump right at the top edge of the door. Sure enough, there was the poor little bat. Donning my gloves again, I gently covered the bat with a small-meshed fishing net which kept it from flying away. I wrapped the net close around the bat, carried it outdoors and opened the net on top of a bush. The elevated release was important because bats have difficulty taking flight from the ground. The little captive promptly flew away. I don’t know yet how it got in, but the little bat knows. Several others have found that secret entrance over the nearly 27 years we’ve lived here. I’ve looked for it repeatedly without success, but I guess I need to keep looking so I can eventually plug it.
The bat I caught and released was almost certainly a big brown bat, the specie most likely to be found inside an Iowa house. Unlike most other Iowa bat species, they don’t migrate to warmer areas for the winter. Small numbers often hibernate in attics or garages. I was advised by a friend who has raised bats that my bat was likely thirsty and could sense water in the sink drain. I’d probably have found the bat right there since it couldn’t climb the slippery walls of the sink, but the towels Sue draped over the sink gave it something to climb on. The little brown bat is the only other specie that often gets into homes, but that’s usually in the warm months since they hibernate in large colonies in caves. Seven other species of bats spend at least the warm months in Iowa. Although a few may sometimes use outbuildings as day roosts, most of them roost in tree foliage or under loose bark. A few species of bats can carry the rabies virus, but, at least according to a reference book I often refer to (“The Mammals of Missouri” by Charles Schwartz), the big brown bat isn’t known to carry the disease. Gloves are still in order if you need to handle a bat since their tiny teeth are sharp and they will bite to defend themselves.
My little bat was letting me know it wasn’t happy being handled by issuing fairly loud clicks and trying to nip my gloved hand. Bats are capable of a range of sounds from those audible to humans to supersonic clicks at far too high a frequency for people to hear. The higher the frequency, the closer the sound waves are together. The closer the waves are, the smaller an object (like a mosquito) they are able to detect. They utter those super high frequency clicks at rates from 20 to more than 50 times a second. The reflected clicks paint their surroundings with sound just as reflected light paints ours. The sound image they create is accurate enough to allow them to capture up to 2,000 small insects during one to two hour evening and dawn feeding sessions. Bats need to eat nearly half their body weight each day to sustain their very high metabolism. As such active consumers of insects, bats are an important part of nature’s check and balance system, helping to keep bugs from bugging us quite as much as they otherwise would.
I’ve been wanting to build a bat house, but I haven’t been able to convince my wife that trying to attract more of them to our yard is a good idea. I already have some lumber that should work well for a bat house, so I’ll have to keep trying to convince her.
Steve Lekwa is the former director of Story County Conservation. Contact him at firstname.lastname@example.org.