The frogs in China produce very loud calls that are, at the same time, both audible and ultrasonic. In Borneo, however, Huia cavitympanum produces some sounds that are purely ultrasonic.
"That was unique and the first time that has been found in any frog species," said Narins, who has studied dozens of frog species. "We are reporting this for the first time."
"With the Chinese frog species, every time you see the vocal sac pulsate, you will hear a sound," Arch said. "With the Bornean frog, sometimes you will see it is calling and you don't hear anything; it's all outside of our hearing range."
The frogs in China and Borneo's Huia cavitympanum are the only two frog species known to have recessed ear drums, Narins said.
In China, the scientists had set up a loudspeaker in the frogs' natural habitat near a river, then played frog calls and recorded the frogs' vocal responses with a microphone and very high-frequency equipment.
Later, they learned of this second species in Borneo with similar ear morphology. Narins and Arch went to Borneo in 2007, and Arch went back last summer.
In Borneo, they lived in a camp with a roof and three walls, with one side open. They slept on a wood floor, protected by mosquito nets. Narins was bitten by leeches and woke up several mornings soaked in blood. They ate noodles and peanut butter.
"It was a huge adventure, and so exciting to study the animals in their habitat," Arch said. "You feel like you're eavesdropping on them."
"There are not many places on the planet left that are so pristine and untouched by humans," Narins said. "It's exciting to go there and wonderful to have a sense of discovering something brand-new. We were there a week and saw only two other people."
|Contact: Stuart Wolpert|
University of California - Los Angeles