IN SEARCH OF THE LEAF-NOSED LIZARD
de Silva Wijeyeratne, G. (2004). In search of the Leaf-nosed Lizard. Serendipity. September 2004. Page 8.
A raptor with white barring on brown wings glided past, below me, on the valley at Corbett’s Gap in the Knuckles wilderness. A shrill, harsh chattering from a Giant Squirrel announced that the raptor had been spotted by one of its potential prey. The raptor was a Mountain Hawk Eagle, found in the wet zone of Sri Lanka, preferring the hills or highlands as its name suggests. As the eagle swept along the valley, powered by a swiftly flowing air stream, another Giant Squirrel relayed the alarm, in a bid to foil the hunter’s efforts.
Corbett’s Gap is to me one of the most reliable places in Sri Lanka to see this scarce bird of prey. I never cease to be thrilled to watch it riding the air currents before it plunges down into the forest canopy to catch its prey. On this occasion I was after another species. I was searching for the Tenent’s Horned Lizard. This is an endemic species of Agamid lizard found only in Sri Lanka . What is more, within Sri Lanka it is found only in the Knuckles Wilderness of Sri Lanka. On my previous visits to Knuckles the lizard had evaded my attempts to photograph it. On this visit in December, I found conditions good for photography. The mist had lifted by late morning and the skies were clear. There was light penetrating through to the Cardamom under layer in the montane forest which had been conserved on the tall peaks around the gap. As the sun came up, it warmed the air and invisible currents of air spiraled upwards creating thermals. A pair of Serpent Eagles called forlornly to each other as they rode the thermals, spiraling up until they were reduced to a dot in the blue sky.
A machine gun like chatter came from the mid canopy signaling the presence of a Grey-headed Flycatcher. I paused to listen and heard Velvet-fronted Nuthatches, Sri Lanka White-eyes, Large-billed Tree Warbler and Dull-blue Flycatchers. They seemed to be part of a mixed species feeding flock which was taking advantage of the security of numbers.
I turned into a rutted road which gave me access to the lizard’s habitat. Not many decades ago, what was now a gravel road was a surfaced road, good enough on which to take a bus. A Common Mormon danced in flight along the road, leading me on a chase. Having tired of the game it suddenly lifted off, over the canopy and abruptly disappeared from view. I stopped to admire the view. I cast my gaze around the cardamom undergrowth hoping to find my target species. To my surprise, I found it, barely half an hour into the search. A male Tenent’s Horned Lizard was perched on a thin stem. Its ‘horn’ was very clear. It was much rounder than the sharply pointed horn of the Rhino-horned Lizard, another lizard endemic to Sri Lanka ‘s mountains. The horn is actually leaf shaped, with the blade of the leaf, perpendicular to the ground.
Out of fifteen species of Agamid lizards found in Sri Lanka , twelve are found only in Sri Lanka . This is a high proportion of endemism and reflects the island’s isolation from the Indian mainland, long enough for the evolutionary forces of speciation to act in the wet zone. The horned lizards of Sri Lanka are in the genus Ceratophora which is endemic to Sri Lanka . In 1871, the Descent of Man and Selection in Relation to Sex by Charles Darwin was published. In it he illustrated the Rhino-horned Lizard, one of Sri Lanka ‘s Ceratophora lizards. He speculated as to the purpose of the horn. Does it play a role in the selection of males by females? Does the horn indicate a degree of sexual fitness of the males? These questions still remain in field biology with answers difficult to arrive at with certainty.
On my part, I was satisfied with encountering yet another of Sri Lanka ‘s unique animals. With plans to protect the Knuckles Wilderness for posterity, the lizard may yet have a future in what is left of this fragile and unique wilderness.
The writer is the CEO of a Wildlife & Luxury Travel Company. To receive his free, monthly wildlife e-Newsletter, e-mail him at firstname.lastname@example.org with “Subscribe Wildlife News” in the message header.