AUSTIN, Texas — Who knew that male bats sing love songs composed of an intricate series of chirps, trills and buzzes? No one aside from the bats, until now.
Researchers at the University of Texas and Texas A&M University have for the first time decoded the courtship songs of Mexican free-tailed bats, a species that roosts beneath the Ann Richards Congress Avenue Bridge here, at Kyle Field in College Station, Texas, and in caves and barns throughout much of the Southwest and Latin America.
Their findings were published in PloS ONE, an online journal of the Public Library of Science.
"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 the 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," Bohn said.
George Pollak , a neurobiologist at UT whose $375,000 grant from the National Institutes of Health underwrote the project as well as other research on bats' sound processing, said the courtship calls of a captive colony of bats in Austin and a wild colony at Kyle Field turned out to be quite similar. That suggests that the bats, also known as Brazilian free-tailed 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," Pollak said. "The point is here you have a mammal that has among the richest and most sophisticated communication repertoires of any animal we know of save man. It must also have part of its brain devoted to producing language."
The researchers recorded the high-pitched songs and played them back at slower speeds to make them audible to human ears; otherwise, people can hear only part of the sound emitted by the bats.
Bohn said bats could prove to be good models for understanding the neural pathways involved in stuttering, certain effects of Parkinson's disease and other disorders.
The researchers were prompted to study the bats' songs by Barbara Schmidt-French, a former science director for Austin-based Bat Conservation International who maintained a hospital of sorts for about 60 injured bats in a shed at her home where she fed them, brushed their teeth and gave them names such as Sid.
She noticed that the singing was associated with mating behavior and sometimes was used to warn other males away.
"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, now with Bat World Sanctuary in Mineral Wells.
"She's basically the Jane Goodall of bats," Pollak said, likening Schmidt-French to the scientist who observed chimpanzees in Tanzania for many years.
Schmidt-French is a co-author of the PloS ONE paper along with Bohn, Pollak, biologist Michael Smotherman of A&M and Christine Schwartz, a graduate student at A&M.
Ralph K.M. Haurwitz writes for the Austin American-Statesman. E-mail: rhaurwitz(at)statesman.com.