Bats Misunderstood, Marvelous, Valuable, Endangered

by Ruel Hinaloc - Date: 2008-08-24 - Word Count: 831 Share This!

‘BATS. I hate them. They re vermin infested, can t see and get tangled up in your hair, spread rabies, suck your blood. Ugh. They make my skin crawl.  Are those also your sentiments?

Actually, bats are much maligned little creatures. They are victims of bad press. They groom themselves fastidiously. Most have good eyesight; none are blind. They have no desire to get in your hair. They rarely have rabies, and when they do, they are not inclined to bite you unlike rabid dogs. More people die annually from bee stings or pet dog attacks, one researcher says. And only three of the nearly one thousand different species of bats drink blood.

Merlin D. Tuttle, founder of Bat Conservation International of Austin, Texas, is recognized worldwide as an authority on bats. He informs us: They make up almost a quarter of all mammal species and come in an amazing diversity, ranging from the world s smallest mammal the Bumblebee Bat of Thailand, which weighs a third less than a penny to giant flying foxes in Java with up to six-foot [1.8 m] wingspans. . . . Some 70 percent of bats eat insects. Many feed on fruit or nectar, and a few are carnivores. He finds them likable, gentle, intelligent, trainable, badly misunderstood, and absolutely


Scientific American magazine agrees: In these days of technological triumphs it is well to remind ourselves from time to time that living mechanisms are often incomparably more efficient than their artificial imitations. There is no better illustration of this rule than the sonar system of bats. Ounce for ounce and watt for watt, it is billions of times more efficient and more sensitive than the radars and sonars contrived by man. July 1958, page 40.

Since the bat s sonar is far more sophisticated than man s, many prefer echolocation as a more accurate word to describe it. As the insect-hunting bat cruises, it emits pulses of sound, each pulse being about 10 to 15 thousandths of a second long. When the sound strikes an insect and the returning echo is received, the bat closes in on its meal. It shortens the length of the pulses to less than a thousandth of a second and increases their emission rate to 200 sound pulses a second, thereby continuously updating the picture it receives as it approaches its prey. In a room strung with fine wires, bats specialized for echolocation miss them all they can dodge wires 0.04 inch [1 mm] in diameter.

The bat s echolocation system is further refined by the changing pitch of each pulse, from about 50,000 to 25,000 cycles per second. As the pitch changes, the wavelength rises, starting at about a quarter inch [6 mm] and reaching a half inch [12 mm]. This helps the bat locate targets of varying size, since this wavelength variation covers the size range of most insects on which it feeds. The bat can also tell from the echo whether the object is an edible insect or not. If it s a hard pebble, the bat will swerve at the last instant.

Most amazing is the bat s ability to recognize and pick up its own echoes in spite of the noise pollution from thousands of other bats. Millions of bats roosting in caves are flying about saturating the air with cries and echoes, yet each bat distinguishes the echoes from its own cries and thereby avoids colliding with other bats. Complicating the problem and magnifying the marvels of bat echolocation, it must be realized that the echoes are very much fainter than the sounds they emit in fact, fainter by a factor of 2,000. And they must pick out these echoes in a field which is as loud as their emitted sounds. . . . Yet the bat is distinguishing and using these signals, some 2,000 times fainter than the background noise. Such a sophisticated sonar system is beyond our comprehension.

Long-eared bats, we are told, can hear their echoes perfectly well if they whisper. Some species have hearing so sensitive that they can hear a beetle walking on the sand from ten feet [3 m] away. They do not, however, hear their own cries when echolocating. Each time one is uttered an ear muscle contracts automatically, thus momentarily shutting off the sound itself so that only the echo can be heard. It is possible that each animal has its own individual sound pattern and is guided by its own echoes.

Bat mothers are commendable. Usually having only one pup a year, some carry it with them when they fly out to feed. Others leave it in a nursery in a cave, packed in a mass, 5,000 [4,000] to a square yard [meter]. When the mother returns, she calls to her baby and baby calls back, and in the pandemonium of millions of squealing babies and calling mothers, she finds her pup and lets it nurse. Some females are very altruistic. Returning from feeding, she will share her meal by regurgitation with other females who were unable to find food.

Related Tags: valuable, marvelous, bats, endangered

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