In another age, before air conditioning (or at least before we had AC), we used to stay outside on those hot Pennsylvania summer nights as late as we could. Back then, before White-nose Syndrome, there were clouds of bats chasing clouds of mosquitoes, and we would pitch pebbles to see them swoop and dive at our stony lures. We would only toss a few, though, since we knew that the little guys had to stay on-task eating real bugs if they were to survive the night. Or at least that’s what we told each other at the time, with all the wisdom of fourth-graders. It might even be true.
Bats use their voices to “see” their world with their ears. Their ultrasonic calls―some of them as loud as car alarms―echo off the world around them, painting a three-dimensional model of their surroundings.
“With this biological sonar they can zip around through the night sky, migrate hundreds of miles to a specific cave, feed on insects, detect a fish breaking the surface of the water just from the sound of the ripples and hear a beetle’s footsteps,” says UT researcher George Pollak, who worked with the private bat colony of bat lady biologist Barbara Schmidt-French. She was observing very elaborate social communication in her little colony and wanted to learn more about what the bats were saying to one another.
“Barbara could tell us exactly what was going on when a bat would deliver a particular song,” Pollak said. “The more we studied these songs and this social interaction, the clearer it became that the songs were all different, there were rules to them and these animals were conveying very specific messages to one another. This was an unbelievably rich repertoire of communication, and it was stunning how effectively the bats were using vocalizations for something other than echolocation.”
A team of German scientists working in Panama tested local bats by playing audio of other bats, including some familiar, local bats, strange bats from other populations, and bats from a different species entirely. The chirping of familiar bats and the sounds of other species didn’t get much of a rise out of the colony, but as soon as they started hearing from strange bats of the same species, the bats got very interested. Whenever the bats answered the calls, they made a unique noise that carried with it an identifiable acoustical signature that no other bat could reproduce. The researchers think this is the bat equivalent of saying, “Hello, it’s me.”
Whether bats have languages depends on whether researchers can learn if they use any syntactical structure in their communication. My gut tells me that, as more research is done on animal cognition and communication, researchers will begin to find more evidence to support arguments for animal languages, as it’s generally much harder to find something if you haven’t been looking for it. If you want to judge for yourself, listen to recordings of the courtship song, a mother calling her baby, and a male defending his territory pulled from the feature story.
So we may find that bats have made a language out of their “sight.” Next post: How certain special humans have taken the opposite approach and made “sight” out of language.