Tree frogs have developed a clever strategy for evading predators while producing mating calls. According to researchers at Purdue University, the frogs overlap their mating calls with neighboring frogs, escaping harm through the use of auditory illusion.
The tree frogs enhance these false perceptions by overlapping their calls at nearly perfect synchrony with nearby frogs. Predators are more attracted to the leading call, which allows the illusive frogs to find a mate without putting their life on the line.
“The male frogs are essentially manipulating the eavesdroppers through creating this auditory illusion,” said study author Henry Legett. “Humans experience this illusion too, it’s called the ‘precedence effect.’ When we hear two short sounds in quick succession, we think the sound is only coming from the location of the first sound.”
Legett led the research with Ximena Bernal, an associate professor of Biological Sciences at Purdue. Studies at the Bernal lab are primarily focused on the relationship between predation and communication, which the researchers simply refer to as eavesdropping.
“The illusion created by the male tree frogs calling in synchrony has no effect on female frogs, which was a surprising observation,” explained Bernal.
“These male frogs have figured out a way to trick their enemies. We thought the females might be more attracted to the leading caller, but it didn’t really affect attraction at all. It’s a win-win for the frogs because it helps reduce attacks from those enemies who were hoping to prey on the male frogs and females are not tricked by the illusion.”
The researchers played back recorded mating calls in both lab and field settings at the Smithsonian Tropical Research Institute in Panama. The team discovered that after the initial male tree frog sends out a mating call, other frogs chime in within milliseconds.
“It’s so fast, it’s almost like a reflex,” said Legett. “There’s no way their brains have time to process that information. They hear their neighbor and they react immediately.”
The study authors said the research has cultivated even more questions about how frogs communicate.
“You have to wonder why a male frog would call first, given that it increases his chances of being eaten,” said Legett. “It’s a very strategic game they’re playing. The frog that calls first might not get lucky that time, but maybe he knows he’ll get his chance the next time he hears one of his friends make the first call. These are the questions we’ll keep asking as we move forward.”
The study is published in the journal American Naturalist.