Scientists have recently introduced to the public fourteen new species of ‘dancing frogs’ they have been tracking in Western Ghats, a lush jungle mountain range in southern India.
Indian biologists say they found the tiny acrobatic frogs, which earned their name with the unusual kicks they use to attract mates, declining in number dramatically during the 12 years in which they chronicled the species through morphological descriptions and molecular DNA markers. They breed after India’s yearly monsoon in its fast-rushing streams, but their habitat seems to be becoming increasingly dry.
“It’s like a Hollywood movie, both joyful and sad. On the one hand, we have brought these beautiful frogs into public knowledge. But about 80% are outside protected areas, and in some places, it was as if nature itself was crying,” said the project’s lead scientist, University of Delhi professor Sathyabhama Das Biju.
Biju said that forest soils lost moisture and perennial streams ran inexplicably dry as researchers tracked frog populations. Biju acknowledged his team’s observations about forest conditions anecdotal as opposed to data collection as they did not have the time or resources to do that.
The study listing the 14 new species was published on May 8th in the Ceylon Journal of Science. The additional species bring the total of known dancing frog species in India to 24.
Only the males dance – actually a unique breeding behavior called foot-flagging. They stretch, extend and whip their legs out to the side to draw the attention of females who might have trouble hearing mating croaks over the sound of water flowing through perennial hill streams.
The larger the frog, the more he dances. He also uses those leg extensions to knock away other males – an important feature considering the sex ratio for the amphibians is usually around 100 males for every female.
“They need to perform and prove, ‘Hey, I’m the best man fr you.’” Said Biju, a botanist-turned-herpetologist now celebrated as India’s Frogman for discovering dozens of new species in his four-decade career.
In October 2011 Biju’s team witnessed a rare mating tryst, and saw the female immediately bury her eggs once fertilized. This confirmed their suspicion the frogs were indeed breeding only after stream levels had come down, and emphasized how vulnerable they might be to changes in rainfall or water availability.
These tiny, delicate frogs (no bigger than a walnut) can be easily swept away in a gushing mountain stream. That is why breeding only happens once the level of the stream drops to the point where the water babbles over boulders and stones, Biju explained. If streams hold less water or dry out, the frogs get stranded without the right breeding conditions.
“Compared with other frogs, these are so sensitive to this habitat that any change might be devastating for them,” Biju said. “Back in 2006, we saw maybe 400 to 500 hopping around during the egg-laying season. But each year there were less, and in the end, even if you worked hard it was very difficult to catch even 100.”
Many of these newly discovered frog species could soon be placed on the threatened species list. Many of the 24 known Indian dancing frog species lives only in a single, small area. Seven were in what Biju described as highly degraded habitats where logging or new plantations were taking over, while another 12 species were in areas that appeared in ecological decline.