Meet the Brazilian Torrent frogs that bob their heads and tremble their toes to say 'hello'

Brazilian Torrent frogs have a huge number of ways to communicate with each other, it has been discovered – the most of all frog species, say researchers from South America. A new study reports that the frogs interact by squealing, toe trembling, head bobbing, flashing signals from their vocal sac, and many more.

The Torrent frogs, Hylodes japi, have a broad range of communication techniques, all catering towards long and short distance messaging, and courtship. This is the first study to describe how frogs use both visual and 'tactile' signals to attract a mate.

"Our study indicates that communication in species of the genus Hylodes is more sophisticated than expected," said Fábio P. de Sá, lead author of the investigation. "Likely, that is particularly true for tropical areas, where there is a higher number of species, and/or where there is higher microhabitat diversity."

The study, published in PLOS, highlights a previously undiscovered way that females encourage mating when she has chosen a suitable mate. She would move so close to the male that they were touching, and place her left arm in front of his head, and her right arm towards his body. Then, by moving both of her arms in a distinctive pattern, she could make the male sound a courtship call.

"We found that the female stimulates the male during courtship by touching him," de Sá told IBTimes. "In addition, we observed that when female combines the touch with an specific visual signal, she trigger courtship calls almost three more times than just touching the partner. The visual-tactile combination likely improves the efficacy of the female's message. Those behaviours are rarely observed because the species is very secretive."

The authors, from Universidade Estadual Paulista and Universidade Estadual do Sudoeste da Bahia, analysed the communication of nearly 70 different individuals over a 15 month period. They discovered that males use eight different parts of their body to interact – toes, feet, hands, legs, vocal sacs, head and body – whilst females only use three – body, hand and arms.

De Sá told IBTimes: "We have a lack of information on neotropical Torrent frog's behaviours. It would be great, and it is necessary new research figures those behavioural patterns out, in Hylodes japi and in another frogs of the Family Hylodidae."