Snakes:

Fascinating reptiles balance nature

By Dhaneshi YATAWARA

Anslem de Silva

Anslem de Silva is the current Co-Chairman of the Amphibian Specialists Group Sri Lanka Net Work. He is also the current Regional Vice Chairman of the Crocodile Specialists Group for South Asia and Iran. Anslem has published nearly 360 papers on various aspects of herpetology local and foreign journals including many books. He has also organized several national and international herpetological conferences in the country including the Fourth World Congress of Herpetology, considered the most prestigious herpetological forum in the world. De Silva over the past five decades has extensively studied herpetofauna in a variety of ecosystems across the country.

His latest book, Snakes of Sri Lanka: A coloured Atlas presents 52 full page colour paintings of the snakes of Sri Lanka that have been drawn using live snakes by the foremost animal artist in Sri Lanka Jayantha Jinasena.

Highlighting the unique attempt of these two Sri Lankans, Professor Kraig Adler of the Cornell University USA commenting on this new work said that a century from now, this folio atlas will be mentioned together with Patrick Russell's "Indian Serpents" and Joseph Fayrer's "Thanatophidia of India" as the greatest works ever produced on the snake fauna of the Indian subcontinent.

Snakes may not be the favourite subject for many of us. Most often it is a subject that brings fear and uncertainty, thus saving the snakes whose lives and habitats are threatened, goes unnoticed. Yet one can be assured that the more you know about this legless carnivorous reptile world the more you will be fascinated about it. More than the fascination snakes play a major role in balancing nature. Nearly 2,200 species live in every nook and corner of the world except Antarctica and a few other islands. All ecological niches of Sri Lanka are practically a home for this rich and diversified snake fauna.

Relict

Common roughside

Of this rich snake diversity the unique feature would be the relict species. Why are they called relict species? With reference to the animal kingdom, relict species means species that were abundant in a large area but now occurs in a few small areas. According to senior herpetologist Anslem de Silva, this island nation shelters ten relict species of snakes that are considered as relict - surviving remnants of the natural phenomena in animal evolution.

"The ten relict snake species in Sri Lanka is the most interesting and people rarely know these facts," de Silva said. He has dedicated over half a century to study and save snakes. According to de Silva the ten relict species are namely Boie's roughside (Lemedilla), Cope's roughside (Kalumedilla), Deranaiyagala's roughside (Kandumedilla), Drummondhay's roughside (ketivalmedilla), Guther's roughside (kudamedilla), Common roughside (dalavamedilla), Blossom krait (Nihaluva), Ceylon wolf snake (Dara radanakaya), Black-spined or the Slender mould snake (Kurunkaravala) and Large Shieldtail (Maha bimulla). These snakes belong to five genera - Aspidura, Balanophis, Cercaspis, Haplocercus, Pseudotyphlops.

Threats and dangers

The threats faced by relict snakes are loss of habitat, habitat fragmentation, the heavy application of weedicides, pesticides during land preparation for agriculture. According to the law, these snakes are strictly protected under the Fauna and Flora Protection Ordinance of 1993. The CAMP (Conservation Assessment and Management Plan) in several workshops and reports held worldwide have categorised these snakes as threatened. The IUCN list also categorises these species as threatened. They are the indicators of direct human threats to a habitat. Snakes play important roles in the eco system, as both predators and prey, both on land and water. Snakes control the rodent population, if left unchecked, can reach plague proportions and devastate cereal crops.

Slender mould snake

Snakes like other reptiles have a mechanism to conserve body heat or to reduce body temperature as required. The snakes become torpid below 40 degrees of Fahrenheit and completely freeze when temperature falls below 32 degrees of Fahrenheit. The upper temperature limit is the more critical for snakes. Smaller snakes reach the critical temperature earlier and quicker than the larger ones. It also depends on the duration of exposure. Certain species will definitely die if exposed to hot sun or if over heated in cages.

Destruction of snakes natural habitats can have profound implications communities. The Department of Wildlife Conservation and the Department of Forests have declared several wildlife protected areas which play a large role in the 'in situ' conservation of snakes, as well as other animals and plants.

Yet, ultimately successful conservation of snakes will largely depend on wide public awareness. Without good extension work encouraging full participation of local people in implementing and maintaining conservation plans there will be little prospects in Sri Lankan snake conservation.

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Rough-sides

As Anslem de Silva explained, out of the ten relict species of snakes, six are of the Aspidura genus, better known as rough-sides. It is the commonest snake in Horton Plains.

Explaining the features of rough-sides de Silva said that one may find ten colour variations among these snakes. Taking 'dalavamedilla' or the common roughside (Aspidura trachyprocta) as an example de Silva explained that the Common roughside a nocturnal small snake has a roundly pointed snout, a cylindrical body and a short tail, which can grow up to about 300mm in length. It feeds mainly on earthworms and grubs. Common roughsides lay eggs under decaying logs, rubble heaps and leaf litter or in loose soil.

Ceylon Wolf snake

According to the researchers roughsides are commonly found in Ambewela, Hakgala, Horton Plains, Lindula, Nuwara Eliya, Pattipola. According to an early research done in 1982 by Gans and Fetcho considered roughsides as a widely distributed form in the central hills, 750m above sea level. It is the commonest snake of the Horton Plains.

The other endemic relict species of snakes belonging to roughsides other than the common roughside are Aspidura copei(Cope's roughside, Kalumadilla), Aspidura deraniyagalae (Deranaiyagala's roughside, Kandumedilla), Aspidura drummondhayi (Drummondhay's roughside, Ketivalmedilla), Aspidura guentheri(Guther's roughside, Kudamedilla) and Boie's roughside (Lemedilla).

Blossom krait

Albert Gunther, one of the most recognised researchers of early days, who brought Nihaluva or the blossom krait (Balanophis ceylonensis ), to the notice of the scientific world in 1858. Nihaluva can grow up to 400 mm in length. Its head is distinct from neck. Body is cylindrical and elongated. Scales are strongly keeled. As de Silva explains gut analysis of this snake have shown a partially digested frog. During the day they hide under leaf litter or under decaying logs.

De Silva, in one of his researches done in 1969 recorded the museum collection localities as Kuruvita and Kegalle. Several other researchers have mentioned Balangoda, Udagama, Peradeniya, Punagala Estate in Yatiyantota, Lenock estate in the Uva Patnas and one from Balangoda, Pelmadulla and Bandarawela.

Slender Mould snake

The Kurun karavala (Rath karavala) or the slender mould snake (Black-spined snake) is a nocturnal snake. The head of the Black-spined snake is long and the snout broadly rounded. The neck is not distinct. The body is slender, long and cylindrical and the tail is short. Its average length is about 350 mm.It lives in damp soil, silted up drains, beneath heaps of decaying leaves and similar places where there are earthworms.

It's inoffensice and requires dark, wet situations and in some tea estates, it is found under refuse heaps close to the workers quarters.The slender mould snake feeds mainly on earthworms. It produces about three to five eggs.

Researchers have found the slender mould to be common in Gampola, Knuckles, Kotagala, Medamahanuwara, Pussellawa and Rangala. Early researches dated back even in 1921 reported the snake seen at Hopewell Estate, Balangoda, Pundaluoya, and Ramboda and researches in 1955 reported observations in Namunukula and Mousakanda. In some tea estates, it is found under garbage heaps close to the workers quarters. The localities of the specimens at the Colombo National Museum are from Gammaduwa and Kotmale.

Yet de Silva's search in January 2001 in localities where the snake had been common earlier, not a single specimen could be located, as the area had been cleared for plantations.

Ceylon Wolf snake

Dara Radanakaya (Cercaspis carinatus) is the Ceylon wolf snake. Dara Radanakaya, a black snake with distinct white rings is a voracious feeder, and mainly feeds on geckos, skinks and even other small non-venomous snakes widely found in rain forests. "I have observed wild and captive ones feeding on a variety of small snakes with the same eagerness as for Geckoes," de Silva explained.

The longest found among the wolf snakes was 620 mm. This is a nocturnal snake, secretive in nature, during the day it hides under fall leaves, logs and under rubble in forests.

It is found in and around rain forests. During the day they conceal themselves under heaps of decaying leaves, logs, in drains, crevices in trees, under stones, in rat holes, sometimes near home-steads.

It is observed that Cercaspis is fond of water or moist places. Even the captive ones were observed very often immerse themselves in water.

"I have observed this snake from Kahawatte (common), Galle, and Kandy," de Silva said. Certain other specimens have been collected were from Galle, Pundaluoya, Ratnapura, Matugama. CAMP Report list Kahawatte, Balangoda, Matale, Kandy, Singharaja forest and also state in many fragmented localities it had been observed. It is present in some protected areas such as Udawattakele, Kandy and Sinharaja forest.

Shieldtail

Pseudotyphlops philippinus or the Maha Bimmulla (large shieldtail) can grow in to 300mm in length. It is mostly found in Namunukula, Kirinda, Kimbulketiya, Palapathwela, Matale. And a CAMP (Conservation Assessment and Management Plan) workshop held in November 1998 showed that using informal field sighting and literature records this snake to be Endangered according to 1994 IUCN Red List criteria.