Frogs in noisy rainforest wave to attract partner

Rainforest frogs have evolved to wave instead of croaking to attract females because waterfalls where they live are so loud, a study has found.

Glass frogs live in habitats deep in the Amazon rainforest in Ecuador where they can blend in to the mossy surroundings and avoid predators.

However, the croaking of the frogs is often drowned out by the background noise of rushing water, even when they are in proximity to their potential mates.

The amphibians have now evolved and developed new techniques in an attempt to attract females, with individual frogs raising their hand above their body while bobbing their head. This is the first time that waving has been spotted in place of the traditional mating call, researchers from the University of California found.

The frogs did not maintain their habit of waving during the entire observation period, which was attributed to the amount of energy that the gesture uses up.

Different species of frog in the Borneo and Indian jungles have previously been spotted dancing as part of their mating rituals, but this was in addition to vocalizations rather than as a replacement.

“A handful of other frog species around the world use visual signalling, in addition to high-pitched calls, to communicate in really loud environments,” said lead researcher Rebecca Brunner, a conservation biologist.

“What's interesting is that these species are not closely related to each other, which means that these behaviours likely evolved independently, but in response to similar environments — a concept called convergent evolution.”

Brunner said that she hoped the findings would draw attention to the vast diversity of species that inhabit the Amazon.

“One of the best things about fieldwork is that nature is always full of surprises, you never know what discoveries you may happen upon,” Brunner said.