August 2009, Volume 7, Issue 8

Bats in the News

Songs of Love

Male Mexican free-tailed bats serenade females with rather remarkable love songs – complex compositions of syllables and phrases that sound like a series of chirps, trills and buzzes, scientists told the Austin American-Statesman.

University of Texas neurobiologist George Pollak told the newspaper  that the research suggests that these bats could be hard-wired for language. “Whether or not it’s absolutely innate, whether it requires learning to be expressed or is partially learned — it makes no difference,” he said. “Here you have a mammal that has among the richest and most sophisticated communication repertoires of any animal we know of save man,” told the newspaper. “It must … have part of its brain devoted to producing language.”
Researchers at the University of Texas and Texas A&M University, working with leading bat-rehabilitator Barbara Schmidt-French of Austin, Texas (Bat Conservation International’s Science Officer at the time) decoded the bats’ courtship songs. Their findings were published in PloS ONE, an online journal of the Public Library of Science. A National Institutes of Health grant to Pollack supported the research, as well as other work analyzing Mexican free-tailed bat calls over the past three years.
 “Bat songs have specific syllable types that are used to construct phrases, and the phrases are put together in specific orders to build the songs,” said Kirsten Bohn, a postdoctoral researcher at A&M and lead researcher for the project.
“Buzzes are almost always at the end of songs. But a bat can do chirp-trill-buzz, and then the same bat can do chirp-trill, chirp-trill, chirp-trill-buzz. So you have this variability,” she told reporter Ralph K.M. Haurwitz.
The research was prompted by Schmidt-French, who maintained a captive colony of several dozen freetails that could not be released back into the wild. Several years ago, she noticed that the singing was associated with mating behavior and sometimes was used to warn other males away. Pollak got the word and the studies began. An earlier report on the bats’ use of phrases and syntax, titled “Bat Talk,” appeared in the Fall 2004 issue of BATS magazine.
“Having them in captivity gave us an opportunity to listen to them in a way that scientists wouldn’t be able to in the wild where the colonies are so huge,” said Schmidt-French, who is now with Bat World Sanctuary in Mineral Wells, Texas.
The scientists recorded the ultrasonic songs and altered the frequency on playback for analysis. The songs of Austin bats were compared with a colony of several hundred thousand Mexican free-tailed bats in College Station, Texas, home of Texas A&M.
After comparing recordings of bats in Austin and College Station, Bohn said in a University of Texas news release, “we discovered they were almost exactly the same. The bats in both places use the same ‘words’ in their love phrases.”
Those results are surprising, she said, because mammals generally do not follow language rules. “With the possible exception of whales, you normally don’t have this type of communication technique,” Bohn said.
Pollak added: “Who would have thought that bats could have one of the most sophisticated and rich vocal repertoires for communications of all animals?”

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