Bats—Misunderstood, Marvelous, Valuable, Endangered
‘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.a 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.
One insect-eating bat, Tuttle says, ‘can capture up to 600 mosquitoes in an hour, eat 3,000 insects in a night.’ One colony of bats in Arizona was found “to devour about 350,000 pounds [160,000 kg] of insects, or about the equivalent weight of 34 elephants, every night!”
Some bats are nectar feeders, rendering valuable service as pollinators. Hovering over blossoms like hummingbirds, their long tongues, tipped with brushlike bristles, mop up nectar and pollen. They are tropical animals and migrate between Mexico and the southwestern United States. Those that eat fruit spread the seeds over wide areas. Tuttle says: “Fruit and nectar-eating bats that disperse seeds and pollinate flowers are vital to the survival of rain forests and to the production of associated crops worth millions of dollars annually.”
New Scientist magazine, September 1988, said: “Farmers who slaughter fruit bats because they consider them to be pests may suffer still greater losses in production because the bats cross-pollinate their fruit trees.” Fruit for shipment is harvested five to seven days before ripening, for local use two to four days early, but bats eat only the unharvested ripe fruit—worthless to farmers. Bat pollination and dispersal of seeds is crucial for more than 500 species of plants and trees. Incidentally, fruit bats do not fly by sonar—they have good eyesight. Often it’s the farmers, not the bats, who are blind.
Nevertheless, the invaluable bats have fallen on hard times. Loss of habitat, pesticides, and indiscriminate slaughtering of large numbers are cutting their numbers from millions to thousands and sending some into extinction. Prejudice, misunderstanding, and just plain ignorance are usually responsible. In Latin America the common vampire bat does require control to safeguard modern man’s livestock, but “poorly trained vampire control agents often indiscriminately kill all bats, unaware that the vast majority of the area’s 250 other bat species are highly beneficial.”
In Australia, thousands of flying foxes, fruit bats, have been wiped out, “despite the fact that some of the area’s most ecologically and economically important trees rely on them” and that “the government’s own investigative findings that crop damage by the bats does not warrant control.” In Israel, “caves suspected of sheltering fruit bats were poisoned—even in nature preserves—inadvertently destroying some 90 percent of the country’s insectivorous bats.”
Old fears concerning bats as carriers of rabies and other diseases are greatly exaggerated: “The odds that a person will die of a bat-borne disease are extremely remote, far less than those of being killed by a dog, a bee sting, or food poisoning at a church picnic.”
Science Year for 1985 sums up its article on bats as follows: “Unfortunately, as the list of the helpful contributions of bats continues to grow, so do the threats to the existence of these creatures. Worldwide, bat populations are declining rapidly. Each year, large bat colonies die out because their habitats are disturbed or destroyed. In Africa and Asia, bats are being hunted in ever-increasing numbers for human food and for use in folk medicines and potions. Fruit-eating bats, which feed chiefly on the fruits of native forests, are often killed by farmers who mistakenly believe that the bats seriously damage their crops. And the myths about bats persist so strongly that millions of the animals are exterminated each year simply because people are afraid of them. Some species of bats are already extinct, and many more are endangered. Until more people come to recognize the value of bats and the need to protect them, the future of these important animals remains uncertain.”
After listing some of the gains made by Bat Conservation International, Merlin Tuttle concludes: “We have only scratched the surface of what must be done if healthy bat populations are to survive. For some, it is already too late and for others, time is running out. The loss of bat populations poses serious, potentially irreversible, consequences for the environment that we all must share.”
Here again, the message is clear: Both ancient and modern history show that man cannot direct his own steps. (Jeremiah 10:23) His love of money, his short-sightedness, and his self-centeredness result in the destruction of the environment—air, water, soil, and plant and animal life—and of people too. Only Jehovah God will stop it. Only he will “bring to ruin those ruining the earth.”—Revelation 11:18.
a All pictures in this article were provided by Merlin D. Tuttle, Bat Conservation International.
[Picture on page 16]
Gambian fruit bats, mother and young
[Picture on page 17]
[Picture on page 17]
Lyle’s flying fox
[Pictures on page 18]
From top down: Common long-eared bat
Heart-nosed bat catching beetle