The Beasts that Hide from Man (13 page)

And, as he informed John Williams, during his visit to Mount Kulal he had succeeded in spotting a second one—unceremoniously ejected from its diurnal seclusion when Adamson had kicked over a pile of pachyderm droppings at the base of the Kulal foothills. Unlike the first specimen, however, this one had flown away without making any attempt to land close by, so Adamson had been unable to make any additional observations.

As Williams noted in what seems to be the only account published until now regarding this coprophilic chiropteran
(Animals
, June 1967), he too became very keen to espy, and possibly even capture, one of these elusive denizens of the dung piles in the hope of identifying their species. And so, to his traveling companions’ great amusement, Williams made a special point from then on of zealously felling as many dry mounds of elephant excrement as he could on the off chance that he might conjure forth one of these perplexing little bats.

Despite such valiant efforts, however, the elephant dung bat has still not been captured, and its identity remains unresolved—but as John Williams kindly informed me during some correspondence, one species already known to science may provide the answer.

The species in question is a rare micro-bat called
Eptesicus (Rhinopterus) floweri
, first described in 1901 by de Winton, and currently recorded only from Mali and southern Sudan. It is commonly termed the horn-skinned bat, calling to attention the tiny horny excrescences that it bears upon the upper surface of its limbs and tail. This species resembles the elephant dung bat in general size and color, but an important additional reason why Williams favors its candidature as the latter creature’s identity is its remarkable preference for day-roosting within holes in the ground, especially among the roots of acacia trees.

As he pointed out to me, this habitat is really quite similar to the crevices and cracks present within dry heaps of elephant dung, hence it is not difficult to believe that this species would utilize these useful sources of daytime roosting sites if such were available. And as the Mount Kulal region of northern Kenya is not only little-explored but also not too far beyond its known distribution range, this provides further reason for looking favorably upon the horn-skinned bat as a realistic answer to the mystery of the elephant dung bat.

In total contrast to the engaging, if somewhat offbeat, history of the elephant dung bat, the case of the Ethiopian “death bird” is unremittingly macabre and horrific, more akin to the gothic outpourings of Poe and Le Fanu than to anything from the dispassionate, sober chronicles of zoology. Yet in spite of this, it is only too real; at the present time, moreover, it is also unsolved. I am most grateful to Queensland zoologist Malcolm Smith for bringing this chilling but hitherto unexamined case to my attention, and for kindly supplying me with a copy of the original source of information concerning it.

It was during an archaeological expedition to Ethiopia, shortly before the country was invaded by Italian troops prior to World War II, that Byron de Prorok first learned of Devil’s Cave, whose grisly secret he subsequently documented in his travelogue
Dead Men Do Tell Tales
(1943). Journeying through the province of Walaga, he resided for a time at the home of its governor, Dajjazmac Mariam, and while there he was approached by one of the servants, a young boy who began to tell him about a secret cave situated roughly an hour’s horseback-ride away, near a place called Lekempti. It was known to the local people as Devil’s Cave, and was widely held to be an abode of evil and horror—plagued by devil-men who prowled its darkened recesses in the guise of ferocious hyenas, and by flocks of a greatly feared form of bat referred to as the death bird.

No one had ever dared to penetrate this mysterious cavern, but de Prorok decided to defy its forbidding reputation, because he thought it possible that there would be prehistoric rock paintings inside (especially as its notoriety would have served well in warding off potential trespassers, who might have desecrated any artwork preserved within its stygian gloom).

When de Prorok told his young informant of his decision to visit Devil’s Cave, the boy was terrified, but after being bribed with a plentiful supply of gifts he agreed very reluctantly to act as de Prorok’s guide—though only on the strict understanding that he would not be held responsible for anything that happened.

The cave was situated high among rocky pinnacles and jungle foliage, but de Prorok succeeded in scrambling up to it, and in removing the several heavy boulders blocking its entrance. Armed with a gun, and leaving his guide trembling with fear outside, he cautiously stepped inside—and was almost bowled over a few minutes later by a panic-stricken pack of hyenas hurtling down one of the passages to the newly unsealed entrance. Seeking to defend himself against a possible attack by them, he shot one that approached a little too close, and the echoes from the blast reverberated far and wide, ultimately reaching the ears of two goatherds who came to the cave mouth to find out what was happening. Here they were met by de Prorok, who had followed the hyenas at a respectful distance during their shambolic exit, and who was greatly shocked by the goatherds’ pitiful state. They seemed little more than animated skeletons, upon which were hung a few tattered rags.

When, with the boy as interpreter, they learned that de Prorok planned to go back inside the cave, they implored him to change his mind, warning him of the death birds. De Prorok, however, was not afraid of bats and made his way once more through the cave’s somber corridors, until he suddenly heard a loud whirring sound overhead. This proved to be a huge cloud of bats, which flew rapidly toward the cave mouth when he fired off a shot in alarm. These, he presumed, must be the dreaded death birds, a line of speculation speedily confirmed when only moments later a rain of bat excrement, dislodged by the shot, began to pelt down upon him from the cave roof, accompanied by an asphyxiating stench that drove him back almost at once to the entrance in search of breathable air.

Outside, he inquired why everyone was so afraid of these bats, to which the two goatherds and the boy all replied that they were blood-suckers, that night after night they came to drink the blood of anyone living near the cave until eventually their unfortunate victims died. This was why the only people living here now were the goatherds (who were forced to do so by the goats’ owners). It also explained the goatherds’ emaciated state. The death birds’ vampiresque activities ensured that none of the goatherds lived very long, but they were always replaced by others, thereby providing the goats with constant supervision—and the death birds with a constant supply of their ghoulish nutriment.

To provide him with additional proof of their statements, the two goatherds took de Prorok to their camp nearby; all of the herders there were equally skeletal—and one was close to death. Little more than a pile of bones scarcely held together by a shroud of ashen skin, this living corpse of a man lay huddled in a cot, with blood-stained rags and clothes on either side, and was so weakened by the nightly depredations of the visiting death birds that he was unable to stand, capable only of extending a wraith-like arm. The goatherds told de Prorok that the death birds settled upon their bodies while they were asleep, so softly that they did not even wake; and that they were sizeable beasts, with wingspans of 12 to 18 inches.

As for physical evidence of the death birds’ sanguinivorous nature, the goatherds showed him their arms, which clearly bore a number of small wounds—the puncture marks left behind by these winged leeches once they had gorged themselves upon their hapless hosts?

Nothing more has emerged concerning this gruesome affair, but for zoologists it would have some significant repercussions if de Prorok’s account could be shown to be perfectly accurate. Only three species of blood-drinking bat are currently known to science—and all three of these are confined exclusively to North and South America!

These are the notorious vampire bats, of which the best known is the common vampire
Desmodus rotundus
, whose range extends from northern Mexico to central Chile, northern Argentina, Uruguay, and Trinidad; its numbers have dramatically increased since the introduction of sheep and other livestock to these areas with the coming of the Europeans, serving to expand the diversity and numbers of potential prey victims for it. The other two species are the white-winged vampire
Diaemus youngi
, recorded from northeastern Mexico to eastern Peru, northern Argentina, Brazil, and Trinidad; and the hairy-legged vampire
Diphylla ecaudata
, ranging from southern Texas to eastern Peru and southern Brazil.

(As a thought-provoking digression, there may also be a fourth, giant vampire bat in existence. Within the
Proceedings of the Biological Society of Washington
for December 7,1988, researchers Drs. Gary S. Morgan, Omar J. Linares, and Clayton E. Ray formally described a new species of vampire, 25 percent larger in size than
Desmodus rotundus
, based upon two incomplete skulls and skeletal remains found in Venezuela’s famous Cueva del Guácharo, home of the extraordinary radar-emitting oilbird
Steatornis caripensis
. Dubbed D.
draculae
, this giant vampire bat’s remains date from the Pleistocene. However, Brazilian zoologists Drs. E. Trajano and M. de Vivo, in a
Mammalia
paper from 1991, noted that there are reports of local inhabitants in southeastern Brazil’s Ribeira Valley referring to attacks upon cattle and horses by large bats that could suggest the continuing survival here of D.
draculae
, although despite extensive recent searches of caves in this area none has been found…so far?)

Over the years, a great deal of misinformation has been dissipated concerning this nocturnal, terror-inducing trio of micro-bats—including the persistent fallacy that they actively suck blood
out
of wounds, and the equally tenacious yet fanciful misconception that they are enormous beasts with gigantic wings into which they are only too eager to enfold their stricken victims while draining them of their precious blood. In contrast, the truth is (as always) far less exotic and extravagant.

Any creature that can subsist entirely upon a diet of blood (sanginivory) must obviously be highly specialized, and the vampire bats are no exception; Canadian biologist Dr. Brock Fenton from Young University in Ontario has lately suggested that they evolved from bats that originally consumed blood-sucking insects attracted to wounds on large animals, but which eventually acquired a taste for the animals’ blood themselves. Yet in overall external appearance these nefarious species are disappointingly mundane—with an unimpressive total length of only two inches to three and a half inches, a very modest wingspan of five to six inches, and a covering of unmemorably brown, short fur. Only when they open their mouth to reveal a distinctive pair of shear-like upper incisors do they display the first intimation of their sinister lifestyle.

These incisors terminate in a central point and have long, scalpel-sharp edges, perfectly adapted for surreptitiously shaving a thin sliver of skin from the body or neck of an unsuspecting (usually sleeping) victim—detected by the vampire’s ultrasonic echolocation faculties. The wound that is produced is sufficiently deep to slice through the skin’s capillaries, but not deep enough to disturb the victim and thereby waken it (or arouse its attention if already awake); stealth is the byword of the vampire’s lifestyle. Aiding the furtive creation of this finely engineered wound are the bat’s canine teeth, shorter than the incisors but just as sharp.

Once the wound begins to seep blood in a steady flow, the vampire, delicately clinging to the flank or back of its victim with its wings and hook-like thumbs
(not
with its sharp claws—yet another fallacy), avidly laps the escaping fluid with its grooved, muscular tongue. It can also suck it up by folding its tongue over a notch in its lower lip to yield a tube, but it only sucks blood that has already flowed out of the wound. In addition, its saliva contains anticoagulants, preventing the blood from clotting, and thereby providing the bat with an ample supply (but causing its victim to lose more than would have been the case if the wound had been inflicted by some other type of sharp cutting implement).

Indeed, one of these anticoagulants, plasminogen activator (Bat-PA for short), shows promise as a powerful drug in the prevention of the severe physiological damage caused by heart attacks in humans, according to a study of its effects by research fellow Dr. Stephen Gardell at Merck Sharp & Dohme Research Laboratories in West Point, Pennsylvania.

The vampire’s teeth, tongue, and thumbs are not the only specialized facets of its anatomy. Its gut also exhibits some important modifications. Enabling the bat to gorge itself thoroughly before bidding its victim a silent adieu, its stomach has an enormous extra compartment—a tubular, blind-ending diverticulum unattached to the rest of the digestive tract and capable of prodigious distension, rendering it able to hold a voluminous quantity of blood. Sometimes the bat can scarcely fly after feeding, because it is so heavy with freshly ingested blood. Also, its esophagus is specialized for efficient water absorption, a necessity for any obligate sanguinivore because blood contains an appreciable proportion of water.

What all of this means in relation to the Ethiopian death bird is that any bat thriving solely or even predominantly upon a diet of blood is inevitably a much-modified species, rigorously adapted for such a lifestyle—rather than a mere opportunist species that in certain localities has switched (through some unusual set of circumstances) from its normal diet to a sanguinivorous existence. In other words, if de Prorok’s account is a truthful one, then surely the death bird must be a species new to science? After all, there is currently no
known
species of Old World bat that is a confirmed blood-drinker. This, then, is plainly one plausible answer to the death bird mystery—but it is not the only such answer.