by Bill Schutt
In the icehouse at Wallerfield, Janet and I took a last look at the amazing little pollinator.
“See ya,” I said, gently flipping the bat upward.
The tiny creature disappeared in a whisper of parchment.
I looked over at Farouk, who nodded and motioned toward the stairwell. “We’d better get going, Bill. We don’t want to be out here after dark.”
“Second that,” Janet said.
I turned to say something to my wife, but she was already moving toward the exit.
“Right,” I said, following the beam from Janet’s headlamp as she sought the comfort of sunlight.
Like nectarivory, blood feeding in bats is another highly specialized lifestyle, but there is little or no convergence between birds and bats, in all likelihood because there’s no competition between the two groups. While there are birds that regularly feed on blood (e.g., vampire finches and, indirectly, those that pick ectoparasites like ticks off of large mammals), none of these birds is an obligate blood feeder like the vampire bats. In other words, no bird species will starve to death in two or three days if it doesn’t secure a blood meal. This means that as far as vertebrate sanguivores are concerned, bats hold the exclusive rights to their aerial and terrestrial niches.*10
So what did the early naturalists have to say about vampire bats, and how did these creatures become forever tied to the growing vampire hysteria that was simultaneously taking place in Europe? How did blood feeding evolve in bats, and why has it never appeared in birds—an older and more diverse group? Oh, and finally, why is just about everything people think they know about vampire bats completely wrong?
It might be best to start with this last question.
Can you tell me why in the Pampas, ay and elsewhere, there are bats that come out at night and open veins of cattle and horses and suck dry their veins; how in some islands of the Western seas there are bats which hang on the trees all day, that those who have seen describe as giant nuts or pods, and that when the sailors sleep on the deck, because that it is hot, flit down on them—and then in the morning are found dead men, white as even Miss Lucy was?
—Bram Stoker
2.
CHILDREN OF THE NIGHT
When the explorers of the New World returned home to Europe in the fifteenth and sixteenth centuries, they were far more concerned with gold, God, and geography than they were with accurate zoological accounts. Amid fanciful tales of sea serpents, giants, and mermaids, there were also reports of bats that fed at night upon the blood of unfortunate humans and their livestock. Although these creatures were generally described as being hideous, with wingspans of up to five feet, nobody actually took the time to figure out which bats were vampires and which weren’t. The rule of thumb seemed to be that the largest and ugliest bats were vampires—and, on both accounts, the explorers were dead wrong.
Early taxonomists contributed significantly to the confusion. Carl von Linné (who actually Latinized his own name) and the morphologist Étienne Geoffroy Saint-Hilaire were responsible for initiating a misunderstanding regarding bats and blood feeding that still exists today. With little knowledge of the bat’s biology and no regard for their actual diet, they assigned scientific names like Vampyrum spectrum (which happens to be a really large bat), Vespertilio vampyrus, Vampyressa, and Haematonycteris to bats that had never so much as snuck a sip of blood.*11
Even card-carrying tropical zoologists got things horribly wrong. Johann Baptiste von Spix, curator of the zoology collection at the Bavarian Academy of Sciences, had spent nearly three years on a collecting trip to Brazil starting in 1817. He returned with thousands of specimens, many never before seen in Europe. One of these was Glossophaga soricina (the pollen-dusted bat I had “swoop-netted” at Wallerfield). Spix described Glossophaga as “a very cruel blood-sucker” (sanguisuga crudelissima), hypothesizing that the creature we now know to be a delicate hummingbird mimic actually used its brushlike tongue tip to reopen the wounds it had somehow inflicted with its tiny teeth.
The chiropteran disinformation campaign continued well into the nineteenth century. By this time collectors were swarming all over the Neotropics in an effort to supply the burgeoning museums and private collections of Europe. Even though naturalists like Charles-Marie de La Condamine and Alfred R. Wallace had begun writing more factual accounts of vampire bat attacks, these creatures were still considered to be mythical by many in the European scientific community. The problem was that while the slaughterhouse results of a nighttime vampire bat attack were easy enough to record, identifying the actual bat that left the mess was more of a poser. And, as it turned out, even when the culprit was correctly identified, prejudice got in the way.
In 1801, in Paraguay, the Spanish cartographer and naturalist Felix D’Azara collected the creature that would eventually become known as the common vampire bat. But even though D’Azara asserted that this was the bat responsible for attacks on humans and livestock, British and French taxonomists thumbed their noses at his claim. In 1810 the same bat was named and described by Geoffroy. Desmodus (literally, “fused tooth”) was named for its unique incisors: a chisel-shaped set of uppers and a uniquely bi-lobed pair of lowers. Unfortunately, there was absolutely no mention of blood feeding in Geoffroy’s description of Desmodus. Similarly, in 1823 Spix named and described a bat that had been collected in Brazil, but it would be years before Diphylla ecaudata would be recognized as a second vampire bat species.*12
It wasn’t until 1832, when Charles Darwin and his servant observed Desmodus rotundus feeding on a horse, that the English-speaking world had a name to associate with the blood-feeding deed.
The vampire bat is often the cause of much trouble by biting the horses on their whithers. The injury is generally not much owing to the loss of blood as to the inflammation which the pressure of the saddle afterwards produces. The whole circumstance has lately been doubted in England; I was therefore fortunate in being present when one was actually caught on a horse’s back. We were bivouacking late one evening near Coquimbo, in Chile, when my servant, noticing that one of the horses was very restive, went to see what was the matter, and, fancying he could detect something, suddenly put his hands on the beast’s whithers, and secured the vampire.*13
(Charles R. Darwin)
Because of similarities in appearance, behavior, and range (parts of Mexico, the warmer regions of South and Middle America, plus the islands of Trinidad and Margarita), Desmodus, Diaemus, and Diphylla were initially placed into their own family, the Desmodontidae. More recently, researchers have reduced them to a subfamily within the large, primarily Neotropical family Phyllostomidae. There are around one hundred and fifty phyllostomids (i.e., members of the family Phyllostomidae) and they’re sometimes referred to as New World leaf-nosed bats. This is because they live in the Americas and most of them have a vertically projecting, spear-shaped nasal structure. Although nose leaves may look menacing, they are actually soft and pliable.
Early naturalists claimed that nose leaves were used by vampire bats as deadly flesh stilettos, to gouge victims before a blood meal. Many years later, scientists studying the strange ultrasonic capabilities of bats uncovered an interesting, though decidedly less gory function for the nasal protuberances. Just as a megaphone can be used to direct the human voice, the nose leaf is actually involved in directing the echolocation calls emitted by the bat. Ironically, nose leaves are greatly reduced in size in vampire bats (like Desmodus) where they function primarily in thermoperception—the ability to sense differences in temperature. This is an adaptation that comes in handy as vampire bats approach their warm-blooded prey in complete darkness. Once the bat gets within around fifteen centimeters of its target, thermoreceptors in the low, ridgelike nose leaf can detect the slight temperature differences that exist in areas of the skin where blood vessels lie just below the surface. The bat uses this information to help determine where a bite will be made.*14
In hindsight, the function of the bat nose leaf was
one more bit of misinterpreted information for early naturalists, who used the presence of this structure to mistakenly categorize over a hundred species of non-blood-feeding bats (e.g., Glossophaga) as vampires. Along these lines, it should also be noted that nose leaves occur in two additional (and only distantly related) families of Old World bats, the Rhinolophidae and the Megadermatidae (the latter is now commonly known as false vampire bats). This is yet another example of convergent evolution, and although neither of these groups have any blood-feeding members, the presence of a nose leaf probably contributed to claims of vampire bats inhabiting Europe, Africa, Southeast Asia, and the Indo-Pacific.†15
Even though the identity of the three vampire bats was not fully known until the 1890s, bloodletting bats have been referred to as vampires since the mid-1700s, and although vampire folklore did not begin with the discovery of vampire bats, it was clearly strengthened by it.
According to folklorist Stu Burns, the word vampire has its somewhat hazy roots in the Slavic proper name Upir, first recorded in an eleventh-century Russian manuscript. Vampire (or vampyre—used hereafter to denote the mythical bloodsucker) is a westernization of Upir (or Upyr) and the word appears to have been coined in English in a pair of 1732 publications. Vampyre refers to a corpse that has returned from the dead to drink the blood of the living. Similar creatures were said to haunt the rural villages of nearly every Slavic nation. Not surprisingly, each culture gave their monster its own name (e.g., vukodlak in Serbia, strigoii in Romania, eretika in Russia, insurance salesman in…well, never mind). It should also be noted that stories of vampyrelike creatures have a worldwide distribution. Bloodsuckers inhabit the folklore and literature of ancient China, Babylonia, and Greece, as well as the pre-Columbian cultures of Mesoamerica (most notably as the Mayan bat god Zotz or Camazotz).
Vampyre hysteria ebbed and flowed throughout Europe in the fifteenth and sixteenth centuries, reaching its peak in the 1730s. At this time it became quite popular to dig up dead bodies, accuse them of crimes, and then smash a stake through their decaying hearts. According to legend, those corpses hoping to avoid skewering often chose to transform themselves into something not quite so corpselike. Although Slavic vampyres never actually took the form of bats, popular transformation destinations included animals or inanimate objects such as fire and smoke. Fear was an important component of most vampyre legends, but some of these creatures would have had a hard time striking terror into your average toddler. For example, Muslim gypsies in the Balkans won’t keep pumpkins or watermelons for more than ten days (or after Christmas) for fear that they’ll transform into vampyres. Thankfully, these vampyre veggies have no teeth—so they’re reduced to pestering people by rolling around the ground, growling, and dripping blood.
Descriptions of how vampyres attacked their prey are almost completely absent from the early folklore, but there is some general agreement that previously healthy victims began wasting away before ultimately succumbing to the vampyre’s supernatural powers.
Some scholars have attempted to explain the multicultural obsession with vampyrism from a criminal standpoint—as gruesome acts committed by individuals exhibiting actual medical conditions ranging from schizophrenia to rabies. On rare but memorable occasions, criminals turned up who were actually obsessed with blood. These “vampyrists” were psychotic rather than supernatural, obtaining gratification by consuming or otherwise coming into physical contact with the blood of others. The most infamous vampyrist may have been the Hungarian countess Elizabeth Báthory. Apparently the countess was quite fond of brutalizing her servants, and after slapping one young woman in the face, she found herself splattered with the girl’s blood. Soon after, Báthory became convinced that the liquid had cosmetic and restorative powers. Ultimately, she may have participated in the torture and murder of over six hundred maidens—all of this mayhem so that she might drink or bathe in their blood.*16 After her trial in 1611, the countess was walled up inside a small chamber within her own castle where she lived out the last three years of life in darkness and solitude. In what might have been an early attempt at a plea bargain, several of Báthory’s assistants avoided similar confinement by having their extremities hacked off and then getting burned at the stake.
Some researchers seeking to explain our fascination with the vampyre phenomenon looked to the deaths themselves rather than the crimes surrounding them. They related fatalities that resulted from supposed vampyre attacks to diseases like anemia, tuberculosis, or the various plagues (such as the Black Death) that spread in wavelike fashion across Europe and much of the globe.†17 Additionally, given the general population’s ignorance about medical conditions like comas, it’s no shock that there were numerous reports of what may have been premature burials and encounters with “dead” people who had suddenly and inexplicably come back to life.*18
Clearly, though, once word of the existence of real vampire bats began to circulate, a new supernatural emphasis on these mysterious (and as yet unidentified) creatures began to take shape. Bats living in Europe, where blood-feeding species had never existed, were gradually implicated as being vampyres. Hysteria and storytelling outpaced reason and science (although to be frank, science had done a lousy job of getting its vampire bat stories straight). Gradually, the folklore of vampyrism began to incorporate the bat and batlike characteristics into its lexicon. Unlike the birds, bats were mysterious and barely glimpsed creatures of the night; they resembled rodents (at least superficially) and flew on leathery wings. Bats were prime candidates for superstition and unwarranted fear, and they would become forever linked to vampyrism in 1897 with the publication of Bram Stoker’s novel, Dracula.
Inspired perhaps by similar stories about how Mary Shelley and Robert Louis Stevenson had come up with their ideas, Stoker (an Irish theater manager and critic) joked that the literary inspiration for his most famous work came from a nightmarish dream that followed a late evening meal of dressed crabs.
Stoker derived the title of his novel from a real-life, fifteenth-century Romanian voivode (warlord or prince). Vlad III, from the principality of Wallachia, became infamous for the means by which he slaughtered his primarily Muslim enemies. Although he utilized a wide variety of tortures (“He blinded, strangled, hanged, burned, boiled, skinned, roasted, hacked, nailed, buried alive, and…stabbed”), Vlad’s favorite torture method was to have victims impaled through the heart, chest, or navel on sharpened wooden stakes. Mothers were stabbed through their breasts before having their babies thrust onto the jagged shafts. In other instances, victims were pierced from the buttocks, upward, by a stake that had been rounded off and lubricated to prevent the impaled from dying too soon.
Slaughtering on a massive scale, the prince reportedly covered the landscape with thousands of staked bodies in various stages of decay. These “forests of the impaled” instilled fear in Vlad’s enemies and eventually earned him the moniker Vlad Tepes (Vlad the Impaler).
How did a murderous Romanian prince lead Bram Stoker to his famous title? It’s quite simple. Vlad’s father (Vlad II), who was also a prince, had been indoctrinated into the Order of the Dragon*19 around 1431 and was thereafter known as Vlad Dracul. Those who knew Vlad the younger could avoid the embarrassing “Impaler” title by instead referring to their prince as Dracula—literally, “son of the dragon.” It should also be noted that since Dracul has a dual meaning in the Romanian language—“dragon” and “devil”—some people have interpreted the name Dracula in a more sinister light.
Even after establishing a link between vampires and vampyres, questions remain about the real-life creatures—questions that have puzzled and intrigued those of us who study them: How did blood feeding evolve in vampire bats? And why (among twenty thousand species of terrestrial vertebrates) is obligate vampirism confined to only three, closely related New World bats?
First of all, as far as the origin of vampire bats is concerned, the fossil record (so important in detailing the life histories of many prehistoric
creatures) is no help here. Although there are several species of fossil vampire bats (including a supersized version, the wonderfully named Desmodus draculae), these bats are clearly vampires, not transitional forms that might shed light on their previous feeding habits. Paleontologists get all tingly at the very mention of transitional forms. But to better understand them, let’s leave vampire bats for a minute to examine what is arguably the most famous of these transitions—one that beautifully illustrates the evolutionary changes that led to the modern horse.
Using the combined results of both classical and modern studies, vertebrate paleontologists have been able to correlate gradual changes in the skull, teeth, and limbs of horse ancestors with environmental changes that took place on the North American continent starting some fifty million years ago (during the early Eocene epoch). One of the groups that evolved to fill the niches left open by the dinosaurs was a rather diverse assemblage of mammals called the Perissodactyla (odd-toed ungulates).*20 Within this group, which also included the ancestors of rhinos and tapirs, was Hyracotherium, a fox-sized creature that inhabited the extensive forests that covered much of the region. With short legs and eyes set in back of a short snout, Hyracotherium was well adapted for a life spent hiding in the underbrush and browsing on soft, leafy plants and fruit.
Starting around twenty-five million years ago (as indicated by clues such as changes in fossil plant species and their seeds), the climate in North America gradually became drier. Forests dwindled and grasslands spread. Some of the small browsing mammals went extinct (as did many other forest types), but others survived, mainly because they evolved adaptations for coping with their new environments. For example, higher crowned (i.e., longer) teeth enabled these mammals to deal with the constant wear and tear of eating the tough, silica-laden†21 grass that had replaced the soft leaves and shoots popular with forest diners.
