Dark Banquet Read Free Page A

chivalrous suggestion and began climbing the darkened stairs.

    One year earlier, at a symposium on bat research, I had gotten up the courage to approach Arthur M. Greenhall, one of the world’s leading authorities on vampire bats. I was in the second year of a Ph.D. program at Cornell and like many grad students I was sniffing around for a dissertation project. (Luckily, the head of my graduate committee, John Hermanson, wasn’t one of those guys who handed you a ready-made project, although I had to admit there were some days when I wished he had.) By this time, Greenhall was in his midseventies but he was still vibrant and inquisitive—as excited about science as anyone I had ever met.
    Born and raised in New York City, he’d had a storied career. In 1933 Greenhall and Raymond Ditmars, his mentor at the New York Zoological Park, had collected the first vampire bat ever to be exhibited alive in the United States. It was a female that turned out to be pregnant, delivering a vampire bat pup several months later. The following year, the young scientist arrived in Trinidad during the height of a major rabies outbreak. He studied the deadly virus and its blood-feeding vector with local scientists and collected additional vampire bats. On his return to the United States, he found he had more specimens than his zoo could display or handle. Greenhall solved the problem by keeping twenty of the creatures in his New York City apartment for two years.
    During a break between research presentations that day, I had spoken to several noted bat biologists about possible differences in behavior or anatomy between the three vampire bat genera,
Desmodus, Diaemus,
and
Diphylla.
From previous studies I had learned that
Desmodus,
the common vampire bat, exhibited an incredible array of unbatlike behaviors, including a spiderlike agility on the ground. Just as interesting to me was the way
Desmodus
initiated flight. In virtually all nonvampire bats, takeoff began with a wing beat that accelerated the animal away from the wall, ceiling, or branch from which it hung. Heavily loaded down after a blood meal,
Desmodus
was renowned for its ability to catapult itself into flight from the ground by doing a sort of super push-up.
    â€œMaybe,” I proposed, “the other vampire bats,
Diaemus
or
Diphylla,
did things a little differently.”
    â€œNot likely,” I was told more than once.
    â€œA vampire bat is a vampire bat is a vampire bat,” chanted several bat scientists. I wondered if there might be a secret handshake that went along with this information, one that I had yet to learn.
    After introducing myself to Greenhall, I told him what the bat researchers had said, adding that I found their responses puzzling.
    â€œWhy’s that?” the vampire maven responded.
    â€œWell, because the rule of competitive exclusion says that if similar animals are competing for the same resource, in this instance blood, then one of three things will happen. One of the animals will relocate. One of them will go extinct. Or one of them will evolve changes, reducing the competition for that resource.”
    â€œAnd since vampire bat genera have overlapping ranges…?” Greenhall interjected, setting me up beautifully for the punch line.
    â€œThey’ve
got
to be different.”
    The old scientist gave me a sly smile. “You’re on to something, kid,” he said. Then he lowered his voice. “Now get on the stick before someone else gets to it first.”
    It had taken me six months to “get on the stick,” but by then my fellow Cornell grad students, Young-Hui Chang and Dennis Cullinane, and I had followed our mentor John Bertram’s lead and built a miniature version of a force platform, a device that could measure the forces applied to a flat metal plate as a creature (in this case, a vampire bat) moved across it. By synchronizing the force platform signals with high-speed