Dark Banquet - Bill Schutt [7]
“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.*6
“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,