Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 29, Number 9;   September, 2002

Frog Sings Like A Bird

by Charlie Whestney

One night, Albert S. Feng and his colleagues went down to the bank of China's Tao Hua Creek to investigate some high-pitched birdcalls, which instead turned out to be the mating cries of a frog. The male Chinese frog, Amolops tormotus, warbles melodies just like a bird to attract females, Feng's team has discovered from slowing down recordings. It is the first time a frog has been found to use diverse rising and falling modulations -- most frog calls go either up or down only.

The sounds are also the first known terrestrial frog noises to extend into the ultrasonic range. "Their range is incredible,"" says Feng, who works at the University of Illinois in Urbana. Male Chinese frogs engage in nightly song battles. They increase the diversity, complexity and frequency of their calls to outdo opponents. So rich is this diversity that no two cries were the same in over 12 hours of recordings from 21 individuals, Feng recalls.

The team now plans to investigate whether the frog's unique anatomy is responsible for its bird-like voice. Called the "sunken-ear frog" in Chinese, A. tormotus males have visible ear canals leading to eardrums within the skull. Most frogs' eardrums sit as a membrane on the edge of their face. The team also plans to study whether the frog can control its two vocal sacs independently, as video recordings lead them to suspect. This could account for the calls' complexity.

References:

Feng, A.S., Narins, P.M., & Xu, C.H. Vocal acrobatics in a Chinese frog, Amolops tormotus. Naturwissenschaften, Published online.