science

University of Texas biologist Rachel Page didn’t get the bats she studied at Barro Colorado Island to wear dreadlocks --- chiroptera, after all, tend to have very short hair. She did, however, get them to come flying whenever she played Bob Marley’s “Buffalo Soldier.”

Page was studying the ways that carnivorous Trachops cirrhosus jungle bats home in on tungora frog calls to find dinner, and noting the interplay between the male frogs’ mating calls and predation. Basically the tungora frog mating call is a long low-frequency “whine,” which may or may not be accompanied by three broadband “chucks.” The frogs that only whine tend to attract less attention from bats, but they also get less notice from female frogs. Those who exclusively whine are more likely to do so apart from other frogs, in niches a bit more sheltered from predatory bats. Those who whine and chuck, on the other hand, are likely to do so in streams and swamps where they have a lot of company, taking the risk that the bats will grab someone else from the crowd instead.

Page caught bats and confined them to an experimental cage, at the bottom of which was set up a screen, disguised with leaves and baited with minnows that the bats also liked to eat, with an audio speaker concealed underneath it. She was studying the bats’ different responses to the whine and the whine and chuck calls to learn more about how the Trachops cirrhosus locates its prey. Like other bats, this species uses high-frequency chirps and corresponding hearing ability to navigate in the dark by sonar, but unlike most other bats, it can also hear and home in on lower frequency sounds like frog calls.

When first tested, the bats would move right in to grab the bait when a whine and chuck sound was played underneath it, but take a little longer to come to just a whine. They wouldn’t respond at all to the calls of toads, which are toxic to them.

Then the fun began. One the bats had been conditioned to come to the sound, Page found that she could gradually change the cues, teaching them to come for the minnow even when a toad call was played. In fact, they’d even come flying when they heard the Bob Marley song.

In response to a question from the audience at the June 10 Smithsonian Tropical Research Institute noon lecture, Page added that after the strange experiments were done, she tried not to leave her confused and starving subjects to hunt inedible toads and make nuisances of themselves at reggae parties. She “deprogrammed” them to be toad-chasing battydreads no more --- providing that the cure works as well as it did in “A Clockwork Orange.”



Also in this section:
Barro Colorado Island's rastabats --- dem irie!
A psychologist looks at a fishing community

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