Tuesday, October 7, 2008

Meet the Bat—The Only Flying Mammal

‘BATS are ugly creatures that live in dark, eerie caves. Their favorite haunts are cemeteries, where they fly among the tombstones on foggy nights. They carry bedbugs. What’s more, they’re blind, filthy and a menace to man.’

In a nutshell, that’s what many people think of us. But as an old bat, let me say something in our defense. Incidentally, calling me “old” can mean that I am getting on to being thirteen years of age, though I know of bats that have lived to be more than twenty.

Oh, yes.! That’s me—that big brown bat over there on the next page. I’m resting on a glass with a bright light underneath so that you can see everything. Take a good look while I tell you about myself and my relatives.

Getting Better Acquainted

We are mammals of the order Chiroptera. There are several hundred species of us throughout the temperate and tropical regions of the earth; so you won’t be able to meet all the relatives.

Basically, we are small, winged, furry creatures whose body resembles that of a mouse. In fact, the Germans call the bat Fledermaus, meaning “flying mouse.”

Among mammals, we alone can fly. “Oh, is that right?” you ask. “What about flying squirrels?” Well, all they can do is glide. We’re different. As Volume I of Mammals of the World puts it: “Bats are the only mammals that fly, although several gliding mammals are referred to as ‘flying.’”

Depending on the species, my relative’s head and face may resemble a bear, a dog, or maybe a fox. One is called the horse-headed bat, for obvious reasons. In some cases, the nose has a growth on it—perhaps one looking like a leaf. Sensory nerve endings are found in those growths.

Bats vary greatly, and I can just imagine someone asking, ‘Who’s the fairest of them all?’ Well, we’re not all ugly, that’s certain. But the wrinkle-faced bat will never win a beauty contest. About the best word for its facial features is grotesque.

What about color? Many of us are brown, gray or black. But there are variations. For instance, the ghost bat is white, maybe with some gray mixed in. There is a fruit-eating bat with a blackish head and dark-brown wings with yellow spots. Of course, these are just examples.

We’ve been known to fool people. At least I don’t think they always know what we are. Consider one small bat of tropical America and Trinidad. It was found roosting at night on the underside of a bridge, in company with cockroaches 51 millimeters (2 inches) long. Of these bats, Walter W. Dalquest wrote: “The resemblance to a cockroach was amazing. The apparent ‘legs’ were the tips of the wings, turned out and back from the body at a 30° angle. . . . It was completely impossible, at a range of 20 feet [6 meters], to tell cockroaches from bats, except that I did not see red-gleaming eyes of the cockroaches.”

Now, if you’ll take another look at my picture, I’ll tell you something about . . .

How We Fly

Actually, our wings consist of thin skin. It stretches from our front limbs along each side of our bodies to our hind legs. The skin or membrane runs between our five digits, that is, the four fingers and thumb.

We usually roost by hanging upside-down by our feet. Generally, we ‘take off’ merely by dropping from a roosting place. We just spread our wings and we’re airborne. But we have no trouble ‘taking off’ from a level place. All we do is jump into the air, using both our legs and arms in the launching operation.

When it comes to wingspan, there certainly are big differences among us. For instance, the little brown bat, with a body under four inches (10 centimeters) long, can spread its wings to fourteen inches (35.5 centimeters). However, the prizewinner among us is the “flying fox,” so named for its looks. These dark-brown bats that inhabit most of the tropics, other than South America, have a wingspread that may exceed five feet (1.5 meters)!

To turn in flight, or to stop, the little brown bat moves its tail downward, making it act like a brake. The lump-nosed bat flies slowly, but it can also hover over something of interest.

Where We Live

Now, a word about living in dark, eerie caves. I must admit that millions of us roost in deep, pitch-black caverns. But did you know that some of us roost in trees, various buildings, ancient temples—yes, and in tombs, too? Why, a number reside in certain Egyptian pyramids! Others take over vacant bird nests and animal burrows. We also live in bell towers and church steeples. Eden Phillpotts once wrote: “His father’s sister had bats in the belfry and was put away.” (Peacock House) You know, of course, that is a writer’s humorous way of saying she was crazy. Well, we’re responsible for that saying because bats sometimes do roost up there with the bells in those towers.

What We Eat

Now let me tell you how we bats can be grouped, not by scientific names, but by our eating habits and physiology. Insect eaters are the most numerous. Generally, they catch their prey in flight. Fruit eaters are tropical bats mostly dependent upon wild fruit, though they are known to cause great damage to orchards.

Some of our number are small flower feeders with long tongues. Pollen and nectar are their fare. Lizards, frogs, small mammals and birds are on the menu of moderate-sized carnivorous bats, although they also eat other things. Then there are the fish eaters. Their powerful feet have hooked claws capable of snatching prey near the surface of the water.

But I’ve left out someone who has given us a bad name, that is,

The Villainous Vampire

For quite some time now fictitious tales have been circulating about dead people who supposedly rise from their sepulchers at night, transform themselves into bats, and suck the blood of hapless humans. You know the old vampire story. Well, mainly in the tropical and subtropical regions of America there are members of my “family” known as vampire bats. They do feed on blood, sometimes that of sleeping humans.

The vampire bat has razor-sharp teeth. In fact, they’re so sharp that the bite is just about painless and the sleeping animal or human rarely is awakened by it. Maybe for some twenty minutes or so this bat gorges itself, taking in so much blood that its little body becomes spherical before the meal is over.

Actually, the amount of blood lapped up (not sucked) is not so great as to endanger humans. But there is another peril. Vampire bats may have rabies. So, left unchecked, their bites can result in hydrophobia and death. Vampire bats also transmit other diseases, such as murrina, which affects livestock. These little bats are dangerous, too, because their bites can cause secondary infection.

Always Harmful?

Does this mean that we’re all harmful villains? No. Some of us serve a useful purpose in helping to control the insect population. Others unwittingly carry pollen from flower to flower. Then, too, bat manure, or guano—plentiful on the floors of bat caves—can be used as fertilizer. Did you know that for two decades guano for fertilizer was acquired in commercial amounts from the noted Carlsbad Caverns in New Mexico? That’s right.

Why, people have considered us so useful that you might say we’ve been “drafted.” During the American Civil War, from guano the Confederate Army got niter (sodium nitrate) for gunpowder. For that matter, while World War II was raging, there was some effort made to use certain bats to carry little incendiary bombs. I’m certainly happy that idea was abandoned!

Oh! Another thing. In some places, like northern India, those bats called “flying foxes” are eaten. People say their meat resembles that of chicken. But I surely hope this idea of humans eating us doesn’t spread. We have enough trouble trying to get away from snakes, birds of prey and other creatures (even some bats) that think we taste good. Incidentally, people under the Mosaic law were not supposed to eat us.—Lev. 11:13-19.

Now, what about the idea that bats are filthy? Well, just listen to what was said by Ernest P. Walker, onetime assistant director of the United States National Zoological Park, Washington, D.C. He remarked: “Bats are by no means unclean. They’re clean as cats—they groom themselves every morning and after each meal.” In grooming, we use our tongue and toes. We just reach up with one of our hind limbs and scratch the back, face and top of the head.

Some people go around saying we carry bedbugs. Occasionally, parasites, yes. But not bedbugs, if that’s any comfort to you!

We’re Really Unique!

Let me tell you a few things that are sort of special about us. Some of us hibernate. Listen to what James Poling said: “The bat is warm-blooded while active but cold-blooded while slumbering. It is able to go into hibernation more quickly and easily than other mammals—which is why it can so readily be put in the refrigerator. [Some of us are kept there in research laboratories.] It just drops its body temperature and falls asleep; the heart slows from 180 beats a minute to three, respiration drops from eight breaths a second to eight per minute. While the bat has some accumulated fat—as it ordinarily has in early fall before winter hibernation—it can live for months in cold storage, unfed and unattended, the ‘motor idling,’ while waiting its turn to come under laboratory scrutiny.”—Marvels & Mysteries of Our Animal World.

Those of us who do not hibernate in caves or elsewhere during the wintertime migrate to places where we can find food. Besides, some of us think that it’s a good idea to spend the winter months in a warmer climate.

Say, did you know that some of our pregnant females get together in maternity colonies? Noctule bats are a good example of this. Sometimes as many as four hundred of their pregnant females get together and set up “maternity wards” in buildings or trees. Furthermore, some female bats evidently store male sperm. In many cases, we mate in the fall and hibernate during the winter, but our females don’t ovulate until the next spring, permitting fertilization to take place at that time. Isn’t that something?

Our Echolocating System

There are people who use the expression “as blind as a bat.” But we’re not blind and some of us see very well. Anyhow, we have a very special way of getting around, one that baffles men of science. It’s called “echolocation,” and this is how it works:

As we fly about, we emit squeaks, chirps, clicks, buzzes and the like through our mouths or noses. Since these sounds range from 25,000 to 70,000 vibrations a second, you humans—with an auditory range up to only about 30,000 vibrations—can’t hear most of the sounds. But, you know, we don’t hear our own sounds either, because when they are sent out our ear muscles contract, momentarily ‘turning off the sound.’ What we do hear is the echo that bounces off any object that happens to be in our path. In that way, even in total darkness, we can maneuver so as to avoid obstacles.

With all this squeaking, buzzing, and so forth, how do we avoid collisions with one another when many of us flock together? “It is possible,” wrote Thomas R. Henry, “that each animal has its individual sound pattern and is guided only by its own echoes. Otherwise, it would seem, there would be complete confusion from the echoes of several hundred bats moving in a flock.”

Why not take matters a little farther? How do insect-eating bats tell the difference between echoes bouncing off obstacles and those glancing off potential meals? As yet, you folks don’t know, and I’m not saying.

Now, what’s the purpose of all this talking? Well, I just wanted to correct some misconceptions about myself and my fellow fliers. Another thing: I really wanted to impress you with our unique abilities. Of course, we came by them naturally. So, the credit really has to go to the Creator of the only flying mammal.

No comments:

Blog Archive