Natural Acts: A Sidelong View of Science and Nature - David Quammen (1996)

ALL GOD’S VERMIN

Wool of Bat

FROM PLINY TO SHAKESPEARE to Tom McGuane, there has been a consensus: Any creatures so grotesquely improbable as bats must perforce lend themselves to some grotesquely improbable human use. The logic may be dubious, but the notion is long-standing.

During the first century A.D., for instance, Gaius Plinius Secundus (that is, Pliny the Elder) suggested in his Natural History that a drop of bat’s blood hidden beneath a woman’s pillow would affect her as an aphrodisiac. Twelve centuries later, Albertus Magnus claimed that smearing bat blood over your face like Coppertone would improve night vision. Macbeth’s three witches, of course, are responsible for that famous stew recipe of which the partial ingredients are

Eye of newt, and toe of frog,

Wool of bat, and tongue of dog.

An early colonial writer named John Lawson claimed that Indian children in North Carolina were often cured of a craving to eat dirt by feeding them roast bat on a skewer (though Lawson doesn’t say whether feeding dirt to adults might possibly cure their urge to roast a bat and make a child eat it). More recently, McGuane’s raucous comedic novel The Bushwhacked Piano describes the scheme of a certain C. J. Clovis, former fat man and one-legged con artist, to contract with mosquito-plagued municipalities for the erection of bat towers—each fully stocked with 1,500 bats dyed Day-Glo orange—for solving the local bug problem. The bats would devour the mosquitoes, theoretically, while the cheerful dye allowed citizens to watch their investment in action. And the fictional C. J. Clovis (as McGuane himself probably knew) is but an echo of historical actuality: During the 1920s, a Dr. Charles Campbell, of San Antonio, proposed “municipal bat roosts” to control mosquitoes and thereby reduce malaria in the American South. At least one of those Campbell-style roosts was built, on Sugarloaf Key in Florida, by Mr. Richter C. Perky, who ran a fishing camp. Although accounts differ as to whether Perky ever actually stocked his tower with imported bats or merely baited it to attract the native ones, orange Day-Glo dye can safely be ruled out. But wait. Even this isn’t all.

Practical bats have just hit the news again. A recent report in American Heritage magazine reveals that the United States government, during World War II, had a plan to use Mexican free-tailed bats for firebombing Japan.

The idea was to refrigerate these bats into hibernation, see, fit each with a small payload of napalm and a little-bitty parachute, see, drop thousands like that from planes over Japanese cities, see, and hope for the best. No I’m not making this up. Your government. The research cost $2 million.

Clearly the bat has captured human imaginations, and that may be because it seems triply oxymoronic: a flying mammal that sees in the dark by listening to its own silent screams. It is in truth an extraordinary animal, equipped with some startlingly sophisticated evolutionary adaptations and represented around the world by a wide variety of different forms. If the bat is grotesquely improbable, so is Pablo Picasso.

Chiroptera is the collective name for this order of mammals, and the main defining characters are familiar: wings formed by thin flaps of skin stretched between hugely elongated fingers; the habit of feeding by night and resting by day; hind feet that lock closed automatically when suspending the body’s weight upside down; and a system of echolocation (at least among the Microchiroptera, one of two suborders), whereby the bat uses varying echoes from its own ultrasonic calls to find prey and steer itself through darkness. Anyone who has ever sat on a suburban porch while summer twilight faded has seen evidence of that last feature’s uncanny efficiency. The erratic diving and swerving and swooping of those small black shapes reflect feeding success, not confusion. Their brains process the echo data at rates unimaginable to us—though some researchers on the human brain have been eagerly studying how they do it—so that a cruising and squeaking bat, while avoiding an array of tricky obstacles, can catch one third its own weight in flying insects within half an hour. Furthermore, they may have developed this sonar as much as 50 million years before we reinvented it.

The female bat possesses a single set of mammaries, from which her young are tenderly nursed, and that fact among others led Carl Linnaeus (the great Swedish classifier) to suppose they were very closely related to humankind. Actually, bats seem to have evolved from some small earthbound insectivorous mammal, a common ancestor linking them with moles and shrews. We don’t know for sure, since the earliest bat fossil (from Wyoming) is fully batlike, and no trace has been found of a transitional form.

But if the assumption about cousinhood with the insectivores is correct, it only highlights still more the uniqueness of bats, because they have gone—in complexity, in diversity, in longevity—so far beyond their relatives. Moles and shrews still feed almost exclusively on insects, while various bat species (especially among the Megachiroptera, that other suborder) have attained much larger sizes and diverged into diets of fruit, nectar and pollen, fish, other bats, small birds and rodents, lizards, and blood. Moles and shrews have remained restricted to specialized environments, while bats have dispersed across every tropical and temperate area of the planet. One genus of bats, comprising sixty species, is more widely distributed than any other genus of mammals except the genus Homo. Most striking, though, is the matter of age. A shrew in the wild can expect a life span of one year, under ideal conditions maybe two. Bats commonly live ten years and longer, in some cases twenty, and achieve this longevity thanks to large measures of sleep and hibernation. One informed guess is that a bat might spend five sixths of its total life just hanging there, sound asleep.

Which seems fairly inoffensive. The bad reputation results, at least in part, from a small group of South American bats classified as the family Desmodontidae—the vampires. Contrary to popular notion, these creatures do not grow as large as ravens, do not possess hollow fangs for sucking, do not usually victimize humans, and do not inhabit Transylvania, or any other part of Europe. Their way of life entails sneak attacks on Brazilian cattle, delicately nipping open a vein with sharp incisors and then lapping away at the flow of blood with a dainty tongue. Also, rather oddly, they prefer to land a discreet distance from the intended cow and make their final approach on the ground, back hunched up high, tiptoeing along like some big-eared tarantula wearing a guilty smirk.

There, I concede, is an unsavory sort of bat—though perhaps even the Desmodontidae deserve credit for a certain roguish charm. Anyway, nobody ever suggested training vampires to serve as official United States weapons of war. That distinction was reserved for Tadarida brasiliensis, the Mexican free-tailed bat.

Tadarida brasiliensis offered one major advantage as tactical weaponry over other potentially deployable bats: abundance. There were 100 million of them roosting peaceably in just a few Texas caves.

Not even Tom McGuane and Albertus Magnus and Richter C. Perky all brainstorming together with Jack Daniels and George Dickel could have dreamed up an idea so robustly demented as this napalm-bat thing. It took a dental surgeon from Pennsylvania named Lytle S. Adams. Seems that Dr. Adams was driving home from a vacation in New Mexico, where he had gazed wide-eyed at millions of T. brasiliensis, like one continuous pelt of lumpy brown fur, covering for acres the ceiling of the Carlsbad Caverns, when news of Pearl Harbor reached him. In first froth of patriotic outrage and desirous of doing his bit, Adams thought of those bats. In less than two months, as the American Heritage article has it, Adams “somehow got the ear of President Franklin Roosevelt and convinced him that the idea warranted investigation.” Under the circumstances, “somehow” seems rather tantalizingly elliptical, but maybe FDR needed a little dental surgery and Dr. Adams pitched his idea before the gas had entirely worn off. Next he managed to interest an eminent Harvard chiroptologist (a bat expert, not a foot doctor) named Donald R. Griffin, and before long the National Defense Research Committee had signed on as a sponsor. By now it was known as the Adams Plan. Eventually the army’s Chemical Warfare Service, the NDRC, and the navy (no reason submarines couldn’t release bats too) were all implicated in the buffoonery.

The first field tests were held at a remote airport in California on May 15, 1943. These were also, apparently, the last field tests. Adams and his colleagues discovered that T. brasiliensis could not always be put into hibernation, nor brought out of it, as promptly as might be convenient. And that the parachutes were a little too bitty. And that the incendiary capsules were a little too large. Groggy bats were tossed out of a plane. Many broke their wings. Some hit the ground without waking at all. It was a waste of innocent animals.

Yet there was poetic justice. A few other bats, armed on the ground with live napalm units but spared the lethal jump, escaped from their handlers. These escapees flew off toward the nearest buildings—as indeed they were supposed to do, though preferably in Japan—which happened to be the airport hangars. The hangars thereupon burned. So did a general’s automobile.

It did not seem auspicious to NDRC officials. The Adams Plan, in mercy to bats and chiroptophiles everywhere, was canceled. And we can guess that Shakespeare himself would have appreciated the shapeliness of that denouement: Fair is foul, said the three witches, and foul is fair.