Dark Banquet (3 page)

“Oh,” I replied, sheepishly. “Right.”

The light from Janet's headlamp swept upward from the bottom of the empty elevator shaft (now below us) to the ceiling. “So where are all the—” Her beam had stopped tracking abruptly.

Illuminated at the top of the chamber were three circular clusters, each composed of a dozen or so black silhouettes, arranged concentrically. They hung silently, reminding me of giant Christmas tree ornaments. Suddenly, one of the fusiform shapes unfurled, revealing wings nearly two feet across.

“Phyllostomus hastatus,”
Farouk whispered. “The second-largest bat in Trinidad.”

“Crawling mother of Waldo,” I muttered, and Muradali threw me a confused look.

“Don't mind him,” Janet explained, keeping her light trained on the bats. “He gets all scientific when he's excited.”

Muradali nodded politely, then began assembling an object that looked suspiciously like a drawstring-equipped butterfly net at the end of a four-foot pole.

I shot him a quizzical look. “A butterfly net?”

“Swoop net,” Muradali corrected, handing it to Janet.

Farouk nodded toward the net, then shined his light up at a cluster of bats. “To catch the ones closest to the elevator door, you lean out over the edge while someone holds your belt or backpack.”

Janet glanced up at the bats, then quickly shoved the net into my hands. Possibly she'd had the same vision that I'd just had, of tumbling down a concrete-lined abyss with nothing except years of rainwater, bat guano, and asbestos to soften the fall.

As I moved into the doorway, it was impossible to chase away the image of that poor woman, stepping off the solid concrete floor and into a bottomless pit of bat-shit soup. “Thanks, hon,” I said.

Janet only smiled.

“We'll leave these bats alone,” Muradali said, moving away from the shaft.

As we quickly followed him, I let out a breath I hadn't realized I'd been holding. “Can we catch vampires like this?” I asked, suddenly feeling a bit braver and taking a few swings at some phantom air bats.

“No,” he replied, picking his way through the debris. “Too smart.”

Later, the scientist explained that early efforts to eradicate vampire bats had resulted in the deaths of thousands of non-blood-feeding species. In 1941, Captain Lloyd Gates was placed in charge of protecting the American forces stationed at Wallerfield from the twin threat of mosquitoes and vampire bats. Gates's less-than-subtle response to the bat problem was to have his men use dynamite and poison gas in caves known to contain bat roosts. Flamethrowers became a popular alternative, but still the vampires persisted, as did their attacks upon the encroaching military men. Also hard hit was the increasing population of locals who had been drawn to the region for the income the base provided. As a result, thousands upon thousands of non-blood-feeding bats were blown up, poisoned, or incinerated. Even worse, these bat eradication techniques were apparently so appealing that over eight thousand caves in post–World War II Brazil were similarly destroyed.
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Farouk recounted how he and vampire bat expert Rexford Lord had been sent to Brazil to pick up some tips on eradicating
Desmodus
from the antirabies groups working there.

“These guys took us to a cave. Then they rolled out a big tank of propane and wired it up with an old-fashioned camera flash, running the wires out the cave entrance.”

He described how everyone waited outside the cave entrance while one of the Brazilians opened up the gas-tank valve.

“Must have been the new guy,” I added.

“They used a triggering box to set off the flashbulb and the explosion ripped through the cave like a bomb,” Farouk said. Then he shook his head and continued. “After the smoke cleared, they asked us to go in and identify the dead bats that we found. And there were
thousands.
All sorts of species—but not one vampire.”

Farouk said that later on the men ventured deeper into the cave and there, lined up above a ledge, was a row of dark shapes.

“They were vampire bats. All of them were looking quite fit and not at all disturbed by the explosion. The bats that died in there were a lot more delicate.”

The Brazilian cave fiasco hadn't solved the vampire bat problem, but it did serve to illustrate how
Desmodus
had evolved to become extremely opportunistic, extremely intelligent, and extremely difficult to eliminate.

At this point Farouk got to the heart of the matter. “Feeding on blood is a tough way to make a living.”

Back at Wallerfield, we moved deeper into the building, using our headlamps to avoid tripping over the ceiling, a concept I was just beginning to wrap my mind around. The acrid ammonia smell was getting even stronger and suddenly we were in Bat Central.

The lights and our movements had finally aroused the aerial residents of the icehouse and now there were hundreds of furry bodies flashing past, their barely discernible high-frequency calls set against the parchment flutter of wings.

I turned off my headlamp and took a couple of swings with the swoop net. Almost immediately I felt a slight difference in the weight of the net and tugged the drawstring tight.

I flicked my light back on. Reaching in a gloved hand, I plucked out a tiny struggling form, manipulating it gently so that the wings were folded and pinned against the body. A struggling animal, no matter how large or small, was far more apt to hurt itself, and the person handling it, if it wasn't fully and comfortably restrained.

Janet and Farouk pulled in close, focusing their headlamp beams on my delicate captive. The bat had an extended snout and a long, protractible tongue that seemed to be equipped with a brushlike tip. Its teeth were tiny and weak and the creature soon gave up trying to bite through my leather batting gloves.
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“Glossophaga soricina,”
Farouk said. “A nectar feeder.”

The bat looked as if it had been assaulted by a powder puff. The “powder” was actually pollen that the creature had inadvertently picked up while feeding. Like hummingbirds,
Glossophaga
and their relatives were vital components of their ecosystems, in fact, over five hundred species of tropical plants were at least partially dependent on bats to pollinate them.

The nectar-feeding lifestyle was also a great example of convergent evolution, in which organisms (in this case several dozen bat species and over three hundred species of hummingbirds) evolved to resemble one another (anatomically and behaviorally), not because they were closely related but because they existed in similar environments or exploited a similar resource. In this instance, the resource was nectar, the sugar-jacked liquid produced by many plants with an evolutionary ulterior motive. While obtaining its meal, this bat (like hummingbirds or insects like bees and butterflies) had been dusted with pollen, pollen that would now be delivered via airmail to some fertile and, quite possibly, distant flower. It was a coevolutionary relationship that had been going on since the flowering plants first evolved during the reign of the dinosaurs.
^*7

Additionally, just as in other examples of evolutionary convergence, there
were
major differences between bat and bird pollinators, and some of these (beyond the obvious daytime-vs. nighttime-feeding habits) were quite significant. For example, hummingbirds, which number around 340 species, are renowned for their ability to hover for extended periods as they feed. Remarkably, they accomplish this maneuver with wing-beat frequencies that can approach ninety beats per second. On the other hand, those relatively few bat species that can hover (certainly fewer than twenty), generally do so for less than a second with wings that max out at around twenty beats per second.

Another difference between bat and bird pollinators concerns the upstroke portion of the wing beat. All bats use the same muscles to raise their wings that humans use to extend their arms out to the side. In both bats and humans, these muscles (i.e., the deltoid and supraspinatus) extend from the back of the shoulder (the scapula) and attach to the upper arm bone (the humerus). When these muscles contract, it's like pulling the strings on a marionette's arms—but with the power to lift the wings coming from muscle contraction rather than a puppeteer.

In terms of flight efficiency, though, the important factor is that in bats the upstroke muscles are located
above
the wing. Since it is more aerodynamically efficient to have as much weight as possible
below
the wing, this extra weight reduces flight efficiency, giving bats their characteristic flittery flight.
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