“I just cannot believe this, what is happening here?” I must have uttered something like this in utmost excitement to Sameer Ali, my research colleague, as we witnessed an extreme and hitherto unknown breeding behavior in a frog species. This was way back in the year 2006, amidst heavy rain in a myristica swamp forest in Kathalekan. Interestingly enough, I did not know either that it would turn out be a new frog species. What followed for the next eight years is a behavioral research story that unfolded each year, adding a new dimension to our current understanding on frogs.
Kumbara Night Frog, Nyctibatrachus kumbara, is a stream dwelling, nocturnal, dark brown coloured frog found in the streams of evergreen to moist deciduous forests of the central Western Ghats. An un-mistaking loud ‘tok-tok’ is how the Kumbara frog calls, mostly during the night. It belongs to the family Nyctibatrachidae, which comprises of genus Nyctibatrachus, endemic to the Western Ghats and genus Lankanectus, endemic to Sri Lanka. The family is one among the three oldest families in the Western Ghats, dating back to about 90 million years. As on date, there are 28 species of Nyctibatrachus endemic to the Western Ghats.
Among all the vertebrates, frogs and toads exhibit the most diverse breeding behaviours. Over 40 breeding behaviours have been reported so far. Among night frogs, we understand breeding behavior to certain extent in Humayun’s Night Frog, Jog Night Frog and Castlerock Night Frog. Kumbara Night Frog’s breeding is not only unique among all the Night Frogs, but is unique among all frogs in the world.
On 26 June in 2006, a Monday, Sameer, Vishnu and Srikanth and I were at Kathalekan to record frog diversity in myristica swamps.
The Kathalekan forest
After our time-constrained visual encounter sampling, I took my camera and note book to work on the breeding behavior in Nyctibatrachus jog. Vishnu and Sameer were moving back and forth within the forest patch to update me with other sightings of breeding pairs. I recorded a complete sequence of Jog Night Frog’s breeding and decided to move on to another pair and record more. On my way, I saw two night frogs wrestling with each other on the ground along a stream. I called both Sameer and Vishnu and explained what I saw. I decided to sit in front of this pair of frogs and observe. That was the first ever breeding behaviour I observed in the Kumbara Night Frog. I was able to observe the complete breeding behaviour 9 more times in the following 8 years. A general pattern of breeding in Kumbara frog is illustrated in the following paragraphs.
Figure 2a-d
A gauging touch – Male individuals often make ‘tok-tok’ calls. The number of their calls increases with a female coming close by. Once a female comes very close to the male, both of them stand upright on their hind limbs and touch each other with their hands. This is perhaps to gauge each other’s height, as the height of an individual is key in the mating process (Figure 2a).
Security – concern of a mother – After the courtship, the male returns to his original spot while the female inspects the place where she is likely to lay eggs. Again, she stands upright on her hind limbs and touches fallen twigs or rock or trunk of a tree, 4 – 5 cm above water where eggs will be laid.
Frogs take the world head on – Soon after the courtship, the male and female hold each other tight with the male on top (Figure 2b). They remain in this position for about 20 minutes. Then, they stand upright (Figure 2c), before the female initiates a hand stand with the male on her back. Both male and female remain in this hand stand position until the female releases eggs (Figure 2d). In a fraction of a second prior to the release of eggs, the male detaches from her but sits close to her watching the process of egg laying. The female releases about 6-8 eggs and sticks them to the twig that she touched earlier. After releasing the egg, the female moves away from the place. Such spawning could be attributed to avoiding predators, especially crabs.
Figure 3a-d
Caring father to fight enemies – Eggs are pigmented and appear obvious on the green or brown background and could be an easy prey for crabs. As the female leaves after laying eggs, the male moves closer to egg clutch and plasters them with mud taken from the stream below. He covers them so cleverly and meticulously that one cannot distinguish the clutch of eggs from surrounding muddy debris. This act can go up to 20 minutes, until the male is satisfied with covering the eggs from all sides.
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