This acrobatic frog builds impressive mud nests

PUNE: In the streams running through the Western Ghats lives a frog that appears to have remarkable skills in acrobatics and pottery, both of which are on display during its mating ritual, which can last up to four hours.
The mating of the Nyctibatrachus kumbara, better known as the Kumbara night frog, involves handstands and a curious mud-packing behaviour, which seems to be the male frog's way of showing he cares for his progeny.
"About a decade ago, while conducting a survey, I first chanced upon these frogs that displayed a very curious behaviour. Since then, we have spotted them on eight other occasions," said K V Gururaja, chief scientist at Gubbi Labs LLP, a research and development centre.
Once the male Kumbara night frog has advertised his call and a female frog has responded, both stand on their hind-limbs and with their forelimbs begin touching one another as well as the place where the egg will finally be laid. This is usually a twig or branch that overhangs the stream, explained Gururaja.
As is seen among many frogs, the male then climbs onto the female but what the two of them do next is rather unusual. They take a 180 degree turn and are now supported on their forelimbs as if performing a handstand.
The male then leaves and the female lays her eggs on the twigs while in this inverted position. She lays between six to eight eggs simultaneously, he explained.
"Once she has laid the eggs, the female leaves the area but the unusual behaviour is far from over. After she leaves, the male begins digging up mud from the stream. He stands on his hind legs and plasters the eggs with mud. He does this for the next 10 to 25 minutes," Gururaja added.
This is parental care, which involves the male frog investing time on the eggs after fertilisation. Usually, it is the female of the species who is responsible for parental care, but in this case it is the male frog, the scientist said.
The mud-packing behaviour of the species gives it its common and scientific name — Kumbara — the name of a community of potters in Kannada.
Gururaja and his colleagues are still working on the reasons behind this mud-packing behaviour of the frogs. "Initially, we thought that it may be a way to prevent the eggs from drying up, but later it occurred to us that it shouldn't be a concern when they are so close to the stream," he said.
The second hypothesis suggested was that it may be a way to protect the eggs against predators. The eggs — brownish on one end and creamy-white on the other — tend to stand out, he added.
But there could be another reason altogether since the male frog has been observed to display these mud-nests to other females. Could it be possible that like weaver birds, the males demonstrate their nest building abilities to potential mates, Gururaja reasoned.
Another possibility could be the reverse of the previous hypothesis. It could be possible that the male frog camouflages the nest, hiding them from the view of other potential mates, he added.
So far, the frogs have only been spotted in three rivers, Tunga, Bedthi and Aghanashini, in an area less than 100 square km. Its International Union of Conservation of Nature (IUCN) conservation status has not been evaluated as yet, but if its distribution is so limited, the Kumbara night frog is sure to be in the threatened categories, Gururaja said.