The Bicoloured Frog’s Wedding Suit

The polka dots had thinned into the skin. The blacks had greyed into sallower shades. But the red-rimmed eyes still gleamed like rubies. Here was the Bicoloured Frog again, dressed for its wedding party

Bicoloured Frog (Clinotarsus curtipes).
In early June this year, just as Agumbe awaited the deluge of the southwest monsoon, we visited the Agumbe Rainforest Research Station there. You might remember that we had posted an encounter with the polka-dotted Bicoloured Frog (Clinotarsus curtipes).
In his Book of Indian Reptiles and Amphibians, J C Daniel mentions that the species begins to breed with the onset of the southwest monsoon and tadpoles can be sighted in plenty in April, May and June. However, in Agumbe, none of the frogs we encountered displayed any hint of breeding colours.
The Kulgi Nature Camp abutting the Dandeli-Anshi Tiger Reserve (15°16’01″N 74°37’01″E), with its broad-leafed north Western Ghats moist deciduous forests, is drier than Agumbe (13°30’30″N 75°5’45″E) and the monsoon had receded by early October, though thundershowers staged a mock-charge in the evenings.
Agumbe, June: Bi-coloured Frog in non-breeding colours
The forest floor was not just a lot drier, the leaf litter was much less than at Agumbe
It was mid-morning and we were out birding along the Birder’s Trail near Kulgi Nature Camp, having just enjoyed watching a mixed hunting party — Velvet-fronted Nuthatch, Paradise Flycatcher, Scarlet Minivets, Brown-capped Pygmy Woodpecker, Greater Flameback and Common Iora — and a much-relieved Sandy commented on the uncharacteristic lethargy of the leeches (there was to be no nightmare-induced macabre storytelling tonight). And then a casual glance at the forest floor revealed this treasure.
Creamy yellow upper body with prominent black dots
The upper body is bright golden-yellow and the dots have almost faded off
The transformation was remarkable. The dots on the upper body had almost faded off and the yellow was much brighter — almost golden. The sharp division between the coloration of the upper and lower parts of the body remained but the glistening black limbs were now brown.
The black limbs have turned brown
The white patch that ran from the snout towards the eye was now yellow and a small black band separated it from the greenish-yellow (almost olive) skin of the sides, which now displayed a dual coloration — a change from the uniform black of the non-breeding form. The most remarkable change, however, was the white-blotched grey of the frog’s underside and the lower half of the belly between the fore and hind-limbs. It gave the frog’s underbelly and sides a rather lichen-patched texture (less on the underbelly than the sides of the lower belly), perhaps a useful camouflage from slithering predators on the forest floor.
The large red-rimmed eye still glowed like a ruby.
Notice the lichen-patched texture of the underbelly that was uniform black before breeding commenced
Behaviourally the frog did not seem to have changed much. It was solitary, did not call, and was not jumpy or nervous. While we photographed, it stayed put, only taking a single jump if we stepped too close.
It did seem a bit late in the season, but the forest had several wet patches and we hoped that somewhere, not too far away, was another individual of the species. Of the opposite sex.
Text and photographs by Sahastrarashmi

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