Bats in Your Hair?
One of the legends that has made many of us more than a little nervous about bats claims that they are prone to crashing into you and getting caught in your hair. Scientists say that is just a myth, but do we really believe them when they say that?
Last week I got a chance to test the theory – and my nerve.
Dawn was just breaking when I stepped from my cabin to discover 20 or more bats zooming around in what seemed to be an aerial get-together.
Steeling myself, I stepped away from the cabin and into the middle of the busiest flight path. For five or ten minutes bats zoomed and dived around me, skilfully avoiding contact, but not trying to keep any great distance either. I have no idea what they were up to. Perhaps it was courting behaviour since several pairs seemed to be chasing each other.
However, it takes more than one day’s resolve to overcome irrational fears. Once I’d arrived at my spot, I remained rooted to the ground, afraid to move even though I well knew that if I stepped into a bat’s path it would have avoided me effortlessly. Any animal that specializes in catching insects on the wing has to be fast enough to avoid a slow-moving ponderous creature like a human. Even though I knew this, it was only when they disappeared into their roosts and the coast was clear that I felt able to sneak from my spot and go back to bed.
Bats have always been a misunderstood animal – surprising when you consider that after rodents, they are more numerous than any other mammal on earth. Their nocturnal habits and secretive behaviour are to blame for the lack of knowledge most of us have about them. Even science has a lot to learn about these creatures which are so difficult to observe in the wild.
Their sonar is of course the best-known and most fascinating aspect of bats. Their highly developed vocal cords emit short pulses of sound and their incredible hearing listens for the echo these sounds make when they bounce off nearby objects. Bats ears can not only distinguish their own sounds from those of other bats in the vicinity, but can tell how big the object is and how fast and in what direction it is moving. We humans can only hear sounds whose frequency ranges from 20 vibrations, or cycles per second, to around 18,000. Bat vocal cords emit, and their hearing picks up, frequencies from 45,000 to 90,000 cycles per second, well out of the range of our hearing.
However, the old saying “blind as a bat” is not accurate. In addition to its other senses, a bat can also see quite well.
The bat’s frantic flight gives the impression of a pretty excitable animal when in fact bats are mostly pretty sedentary. The little brown bat, the one most often seen in Ontario, is only active for a couple of hours a night, usually just after dusk. It spends the other 22 hours in its roost, usually in a tiny corner of a building or a hollow or crevice of a tree if no building is available.
But when active, the little brown bat eats an incredible number of insects – for which we should be deeply grateful. Its voracious appetite is due to its large expanse of skin, which, because of its large ears and wings is way out of proportion to the size of its body. Since mammals lose heat through their skin, the bat must make up for this loss by eating large quantities of food. For this reason, too, bats hang around in clusters to conserve heat by close contact with their neighbours.
The eight species of bats in Ontario all hibernate for the winter, with the exception of the red bat which migrates south with the birds. Most of the hibernating bats leave their summer roosting site to congregate together in caves and abandoned mines. The little brown bat needs a humid setting that will not dry out its skin which must remain moist and supple. In a dry place bats will soon die and their bodies quickly become mummified. Because of huge moisture loss through their skins, bats are big water-drinkers.
Although bats mate in the fall, the female retains the male’s sperm in her body until she awakens after hibernation in the spring. Only then are her eggs fertilised. Since all bats in a cluster wake at the same time, their eggs are fertilised in unison and they give birth all together almost simultaneously after about 2 months, each to a single young. The young are mature at two and live between five and ten years, sometimes as long as twenty.
The best place to observe bats-on-the-wing is in a dark countryside under an isolated but strong lamp. The light attracts insects which in turn attract these fascinating but too-little-known creatures.
Elaine Farragher, September 1988
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