Declaration of Our Core Commitment to Sustainability Dilmah owes its success to the quality of Ceylon Tea. Our business was founded therefore on an enduring connection to the land and the communities in which we operate. We have pioneered a comprehensive commitment to minimising our impact on the planet, fostering respect for the environment and ensuring its protection by encouraging a harmonious coexistence of man and nature. We believe that conservation is ultimately about people and the future of the human race, that efforts in conservation have associated human well-being and poverty reduction outcomes. These core values allow us to meet and exceed our customers’ expectations of sustainability.
Our Commitment
We reinforce our commitment to the principle of making business a matter of human service and to the core values of Dilmah, which are embodied in the Six Pillars of Dilmah. We will strive to conduct our activities in accordance with the highest standards of corporate best practice and in compliance with all applicable local and international regulatory requirements and conventions. We recognise that conservation of the environment is an extension of our founding commitment to human service. Front Cover: Chrysopelea ornata (Ornate flying snake (E); Pol mal karawala, Malsara, Panina karawala (S)) One of the most vibrantly coloured snakes in Sri Lanka that has been aptly named Malsara (u,aird) which in Sinhalese means ‘cupid’. Unfortunately this harmless snake has become an innocent victim owing to its colouration (red, black, and yellow), which symbolise ‘danger’ in the animal world. Commonly found in the canopy of tall trees of the wet zone, this is a rare species in the drier parts of the island. Humans living on the periphery of forests are likely to encounter them more often, as they will come to feed on geckoes commonly found in human settlements, and unfortunately when they do, they are often killed due to misplaced fears. Back Cover: Left to Right Python molurus (Rock python), Echis carinatus (Saw scaled viper), Eryx conicus (Sand boa)
We will assess and monitor the quality and environmental impact of its operations, services and products whilst striving to include its supply chain partners and customers, where relevant and to the extent possible. We are committed to transparency and open communication about our environmental and social practices. We promote the same transparency and open communication from our partners and customers. We strive to be an employer of choice by providing a safe, secure and non-discriminatory working environment for its employees whose rights are fully safeguarded and who can have equal opportunity to realise their full potential. We promote good relationships with all communities of which we are a part and we commit to enhance their quality of life and opportunities whilst respecting their culture, way of life and heritage.
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This publication may be produced in whole or in part and in any form for educational or non-profit purposes without special permission from the copyright holder, provided acknowledgement of the source is cited. No use of this publication may be made for resale or any commercial purpose whatsoever without prior permission in writing from the copyright holder. Disclaimer The contents and views in this publication do not necessarily reflect the views or policies of the copyright holder or other companies affiliated to the copyright holder. Citation Wickramasinghe, L. J. Mendis (2014). Recognising Deadly Venomous Snakes from Harmless Snakes of Sri Lanka. Colombo, Sri Lanka: Ceylon Tea Services PLC. Text & Photographs by L.J. Mendis Wickramasinghe Assisted by Nethu Wickramasinghe, Dulan Ranga Vidanapathirana and Gayan Chathuranga Design and Layout by Kasun Pradeepa. Wild Studio ISBN: 978-955-0081-12-7
Ceylon Tea Services PLC MJF Group 111, Negombo Road Peliyagoda Sri Lanka
Contact info@dilmahconservation.org January 2014.
Recognising Deadly Venomous
SNAKES from Harmless Snakes of Sri Lanka Authored by
L. J. Mendis Wickramasinghe Printed and bound Karunaratne & Sons (Pvt)Ltd.
Advised by Channa Bambaradeniya, Ph.D. & Gernot Vogel, Ph.D. Edited by Devaka Weerakoon Ph.D.
Message from the Founder An unfortunate fear and loathing of snakes permeates through our society, and since childhood, I too have been no exception to this disappointing lapse. It is sadly commonplace for those who encounter snakes to attempt to kill them, owing to suspicions they harbour that all snakes are poisonous or deadly. I have learned that these misconceptions which cause panic and revulsion stems from a poor understanding of snakes and their habits, coupled with the inability and unwillingness to distinguish between different species of snakes. This results in the thoughtless killing of snakes, even though many types found in Sri Lanka are largely harmless and do not attack unless threatened. I have also observed that this has proved to be a particular challenge within the plantation sector, and tea estates must be no exception for efforts in biodiversity conservation. Mr. L. J. Mendis Wickramasinghe has compiled a comprehensive illustrated field guide on behalf of Dilmah Conservation, which not only seeks to help readers easily identify snakes so that they will be able to deal with these creatures safely and considerately, but cultivate an interest and appreciation for the vital ecological role they play in pest control. It is my wish that this field guide will spark the curiosity of students in particular, and motivates them to pursue further learning and contribute towards the study and conservation of reptiles in Sri Lanka. I firmly believe that it is the duty of Dilmah Conservation to strengthen its commitment to promoting socially and environmentally conscious educational initiatives towards fostering awareness, appreciation and respect for Sri Lanka’s natural wealth. Thus, I am confident that this publication ‘Recognising Deadly Venomous Snakes from Harmless Snakes of Sri Lanka’ will mark a small but noteworthy contribution by Dilmah Conservation towards bridging the gaps in knowledge about snakes, minimising damaging misconceptions and thereby enabling their conservation by helping a broad audience improve their understanding.
Merrill J. Fernando Founder – Dilmah Conservation
Recognising Deadly Venomous
SNAKES from Harmless Snakes of Sri Lanka Authored by
L. J. Mendis Wickramasinghe Advised by Channa Bambaradeniya, Ph.D. & Gernot Vogel, Ph.D. Edited by Devaka Weerakoon Ph.D.
08
Foreword
Preface
Snakes are often considered deadly and dangerous and therefore persecuted by humans like no other group of animals. Yet snakes are an important part of natural and manmade ecosystems as they prey on many species that we consider as pests and help to keep their populations under control. One of the biggest threats to snakes today is inadvertent killing by humans. Much of these killings result due to our widespread fear and loathing towards snakes, as well as great deal of misinformation and misconceptions regarding them. In Sri Lanka, as this book clearly indicates, only 21 out of the 102 recorded species of snakes are deadly poisonous. Out of these only 5 species are known to cause fatalities in humans. Therefore, most of the snakes that we encounter in life are likely to be harmless. Further, snakes do not ordinarily attack humans unless provoked, startled or injured. Therefore, we can avoid the inadvertent killing of these useful creatures by becoming more aware about them. One important aspect of awareness is to develop an ability to identify poisonous snakes. This will not only help save snakes but will also be useful to save the life of a person bitten by a snake, as it is important to establish the identity of the snake before providing treatment to the snake bite victim. Identification of snakes is not a difficult task as most poisonous snakes show characteristic colour and scale patterns that will enable correct identification. However, many non poisonous snakes tend to mimic the colour patterns shown by poisonous species as a form of defense from their predators. As this is a trait that has evolved to confuse their predators it is not surprising that we too would be confused by this, which in this case is not working towards their favor. This book attempts to educate the reader about the value of snakes as well as how to differentiate poisonous snakes from non poisonous species. I am sure this book will help the reader to lessen their fear and hatred towards snakes while at the same time develop an appreciation and respect for their role in our ecosystems.
Snakes are a group of animals which have been especially revered in the Sri Lankan context. According to ‘Deepawamsa’, an ancient chronicle of Sri Lanka, the ‘Naga (Snake)’ people, one of the four powerful tribes in Sri Lanka who ruled the Northern and Western parts of the Island during the 6th century BC to 3rd century BC, were snake worshippers. King Buddhadasa, the only monarch known to not only possess the skills of a physician and a surgeon, but also those of a veterinarian, was fabled to have treated a sick cobra as far back as 340368 AD, revealing how compassionate ancient people were towards snakes. The ruins of the ancient cities also speak of the harmony between snakes and the people of Sri Lanka. These include guard-stones with a cobra-king providing protection to the premises, and seven hooded cobra statues built to protect the tanks constructed by the ancient Kings. However, changing times and four centuries of colonization have resulted in these ancient traditions being replaced by a lack of tolerance towards snakes. Like in the rest of the world, snakes have now become a feared group of animals in Sri Lanka.
Prof. Devaka Weerakoon
Department of Zoology, University of Colombo
The feeling of fear evoked by snakes coupled with an inherent reaction of disgust often results in attempts to kill snakes. This fear could be justified when considering the number of deaths caused annually by poisonous snakes. Further, superstitions and misconceptions also play a significant role in vilifying these creatures. In reality, only few species of snakes can actually cause harm to people. Further, many snakes play a beneficial role in both natural and manmade ecosystems, as the natural enemies of many species who can otherwise undergo a massive population growth and become pests to man. Therefore, humans must find a way to co-exist with snakes on this limited land we have. As such, we must become aware of how to co-exist. This book intends to provide the reader with a broad overview about snakes in Sri Lanka, with special emphasis on deadly poisonous snakes, and their identification.
Ruins of a seven hooded cobra, protecting the water near Urusita Wewa, Embilipitiya
Contents Foreword .................................................................................................... 8 Preface ........................................................................................................ 9 Acknowledgements ..................................................................................... 10 1. Snakes of Sri Lanka ..................................................................................... 12 1.1 Snake bites in Sri Lanka ....................................................................... 16 2. What is a Snake? ........................................................................................ 17 3. Identification of Venomous snakes ............................................................... 20 3.1 Mimicry ........................................................................................... 20 4. Kraits .......................................................................................................... 24
Acknowledgements
10
This book was made possible thanks to Dilmah Conservation, who invited me to write a simple guide for the general public to identify venomous snakes in Sri Lanka. The fieldwork was made possible thanks to the Biodiversity Secretariat of the Ministry of Environment who provided funds and the Department of Wildlife Conservation who provided the permit to conduct the research work. My heartfelt appreciation goes to Mr. Dulan Ranga Vidanapathirana and Mr. Gayan Chathuranga for assisting me while photographing and handling the snakes in the field. I would also like to thank Dr. Channa Bambaradeniya for his valuable comments and my colleagues at the Herpetological Foundation of Sri Lanka (HFS), for various courtesies. I wish to thank Dr. Gernot Vogel whose invaluable comments undoubtedly improved the quality of this book. I would also wish to extend my gratitude to Prof. Devaka Weerakoon for the valuable time and effort he took to edit the text to its final form in which it is presented here. Last but not least to my dear wife Nethu, for her commitment to making this a success!
4.1 Bungarus caeruleus (Thel karawala/ Indian krait) ................................. 26 4.2 Non venomous species that mimic the Indian Krait ............................... 28 4.2.1 Lycodon aulicus (Alu radanakaya/ Wolf snake, House snake) .............. 28 4.2.2 Lycodon osmanhilli (Mal radanakaya/ Flowery wolf snake) ................. 30 4.2.3 Lycodon striatus (Kabara radanakaya/ Shaw’s wolf snake) ................... 31 4.3 Bungarus ceylonicus (Mudu karawala/ Sri Lankan krait) ...................... 33 4.4 Non venomous species that mimic the Sri Lankan Krait ...................... 35 4.4.1 Cercaspis carinata (Dhara radanakaya/ Sri Lanka wolf snake) ............. 35 4.4.2 Dryocalamus nympha (Geta radanakaya, Geta karawala/ Bridal snake) 37 4.4.3 Dryocalamus gracilis (Meegata radanakaya/ Scarce bridal snake) ......... 38 5. Vipers
........................................................................................................ 39
5.1 Daboia russelii (Thith polanga/ Russell’s viper) ..................................... 40 5.2 Non venomous species that mimic the Russell’s viper ............................ 42 5.2.1 Eryx conicus (Wali pimbura, Kota pimbura / Sand boa) ..................... 42 5.2.2 Python molurus (Dara pimbura, Ran pimbura/ Rock python) ........... 44 5.3. Echis carinatus (Wali polanga/ Saw scaled viper) .................................. 46 5.4. Non venomous species that mimic the Saw scaled viper ......................... 48 5.4.1 Boiga triginata (Garandi mapila, Ran mapila, .................................. 48 Kaeta mapila/ Gamma cat snake) 6. Cobra
......................................................................................................... 50
6.1 Naja naja (Naya or Nagaya/ Indian cobra, Spectacled cobra)
................ 50
Literature cited ................................................................................................. 53
1. Snakes of Sri Lanka Sri Lankan snake fauna comprise of 102 species belonging to 10 families 1-4. Out of these 102 species, 87 live on land, 14 live in the ocean, and the remaining one inhabits brackish water. Nearly 49% (50 species) of the snake species found in Sri Lanka are endemic to the island, or do not occur naturally anywhere else in the world 5.
Trimeresurus trigonocephalus (Green pit viper (E); Pala polanga (S)).
Left: An Enhydrina schistosa (Hook nose sea snake (E); Valakkadiya (S)) killed by fishermen. Right: A close up image showing the typical flat tail of sea snakes.
12
The snakes of Sri Lanka can be categorized into four groups, depending on the lethality of their venom. Accordingly, 21 species can be considered as deadly venomous; five species as moderately venomous and 12 species as mildly venomous. The remaining 64 species are non-venomous1-4, 6-10. This demonstrates that the majority of snake species (63%) are in fact, harmless. Members of the genus Boiga (Cat snakes (E); Mapila (S)), one of the most feared snakes, belong to the mildly venomous group, and its bite causes much less pain than one inflicted by a hypodermic needle. Moderately venomous snakes include four species of the genus Hypnale (Hump-nosed vipers (E); Kunakatuwa (S)), and Trimeresurus trigonocephalus (Green pit viper (E); Pala polanga (S)). Their bites will result in harmful effects such as gangrene, necrosis, tissue damage, kidney failure, blisters etc. Hypnale hypnale, which was previously known to be a moderately venomous snake 11 has now been classified as a deadly venomous snake12-16.
Left: Hypnale hypnale (Hump nosed viper (E); Kunakatuwa/ Mukalang thelissa (S). Right: Close-up of the head showing the typical posture of hump nosed vipers, keeps their head slightly angled approximately at 45º.
Likewise, Echis carinatus (Saw-scaled viper (E); Vali polonga (S)) is restricted to the dry and arid zones of the island. Moreover, as the snake is very small in size (30 cm SVL), the amount of venom excreted in a single bite is very small17.
Left: Hypnale zara (Zara’s hump nosed viper (E); Pahatharata thelissa (S)). Right: Close-up of the head showing its pointed snout/ rostral appendage, which is the most relible identification character for all hump nosed vipers in common.
Calliophis melanurus (Sri Lanka coral snake (E); Depath kaluwa (S)). A very small snake similar in size to an ink tube of a carbon pen.
14
Left: Hypnale nepa (Merrem’s hump-nosed viper (E); Mukalan thelissa/ Mukalang kunakatuwa(S)) Right: Close-up of the head.
Out of the 21 species of snakes considered to be deadly poisonous, fourteen are sea snakes. These sea snakes are non-aggressive in nature, and since they are found only in deep waters they hardly interact with humans. Out of the remaining seven deadly poisonous species, two are coral snakes (Calliophis melanurus and Calliophis haematoetron) incapable of inflicting damage to humans owing to their small size (SVL, 30 cm). Out of the five species remaining, Bungarus ceylonicus (Ceylon krait (E); Mudu karawala (S)), is non-aggressive in nature and is to some extent an uncommon species.
Therefore in Sri Lanka, the majority of human deaths occur as a result of lethal snake bites caused by the 3 remaining species of deadly poisonous snakes: Bungarus caeruleus, (Indian krait (E); Thel karawala (S)), Naja naja, (Indian cobra (E); Nagaya (S)), and Daboia russelii (Russell’s viper (E); Thith polanga (S))14, 16, 18-19. Due to the lack of understanding of snakes in Sri Lanka, they are frequently killed regardless of their identity. Therefore, the ability to identify at least these three species will save the lives of human beings and a vast number of innocent and beneficial snakes. Therefore, the primary aim of this book is to help the reader to correctly identify life-threatening species, and thereby prevent the futile killing of a large proportion of harmless snakes.
1.1 Snake Bites in Sri Lanka
In Sri Lanka, close to 37,000 snakebite cases are reported annually to hospitals16, of which about 100 cases will result in the death of the victim. Most of these deaths occur in rural areas where the patients are brought to the hospitals at a very late stage due to the lack of transportation facilities. If the patients are given medical attention without delay these deaths can be avoided. We are attacked by snakes mostly due to our lack of understanding of what their preferred habitats might be. Apart from their naturally occurring habitats like termite mounds and bandicoot tunnels, venomous snakes like Cobras, Russell’s vipers and Kraits are attracted to places such as piles of rock used for construction work where there are plenty of empty spaces for them to hide, garbage mounds, stacked bricks, piled up coconut leaves, coconut roots, wood piles etc. In other words, while destroying their natural habitats we too are unintentionally recreating ideal habitats for them. Additionally, we also create ideal conditions for their prey, such as rats. Therefore, it is not a real surprise when snakes, like all other living beings, are attracted to places where there is plenty of food and shelter.
16
The human-snake conflict is an issue that will continue to escalate due to the ever increasing human population and the consequent loss of natural habitat. However, the threat from snakes to humans remains comparatively low (approximately 100 deaths per year compared to other hazards such as accidents involving vehicles which claimed 2,721 lives and injured another 26,847 persons in 2010 alone). Despite this, we are not afraid to travel on the roads, in a vehicle as we are aware of the different risks associated with modes of transportation. However, our fear of the unknown (such as our inability to differentiate a commonly encountered harmless snake from a deadly venomous snake or our lack of understanding about their ways) drives us to kill them on sight.
2. What is a Snake ? Many people fear snakes because they believe that: • • •
All snakes are venomous and are seeking to kill humans. Snakes have an unpleasant skin which is either sticky and slimy or scaly; Snakes are dirty and unclean.
However, it should be noted that many people reach the aforementioned conclusions without even having touched a snake or closely examining them. In reality, when a person is given the opportunity to closely inspect a snake, they become pleasantly surprised when they learn that these assumptions are baseless. •
• •
Majority of snakes are non-venomous and attack only if they feel threatened, in order to catch their prey, and not because they enjoy it. It needs to be understood that snakes play an important role in maintaining the ecological balance by controlling the population size of many species. Snakes in fact possess a clean, dry skin. Some snakes are in fact very colourful and beautiful.
However, these animals have gained an unpopular reputation due to various reasons, and as a result they are killed by people who are unaware of their ecological importance. They are an integral part of a balanced ecosystem and play a significant ecological role as predators, thereby controlling populations of many species including pests such as rodents. Snakes are also good indicators of environmental pollution. An additional benefit of these creatures is that their venom,
which contains proteins, can be extracted for medicinal purposes, hence possessing an economic value. Snakes come in a diverse range of sizes, and are entirely carnivorous typically swallowing their prey whole. Depending on their size, their prey also varies from small insects consumed by small earth snakes like Typhlops to heavy animals consumed whole by large pythons.
Left: The scale arrangement of Cylindrophis maculate (Sri Lanka pipe snake (E); Depath naya (S)), a harmless burrowing snake. The image shows its tail rolled up, mimicking a hood of a cobra a typical defense mechanism against predators.
All snakes have razor sharp teeth, which are used to prevent their prey from escaping., They do not use their teeth to break their prey into smaller parts or for chewing since they swallow their prey whole. Fangs are specialized teeth that are only found in venomous snakes. These fangs are tube-like and makes it possible for the venom to be introduced efficiently into a wound once the snake strikes, thus immobilizing the prey in the shortest possible time. 18
The venom and its delivery system are special tools they have developed through years of evolution, and it must be emphasized that their main purposes are to aid the capture of prey and self-defense (because snakes are both predators and prey), and are not intended specifically to hurt humans as many seem to believe. Snakes that lack venom resort to constriction in order to immobilize their prey.
Above: A Green pit viper, with wide open mouth showing its fangs. Left: Coeloganthus helena (Trinket snake (E); Katakaluwa (S)), a slightly venomous snake, with its mouth wide open showing its teeth. The orange arrow shows its fangs positioned towards the rear of its mouth, such fangs are known as back fangs.
As mentioned before, not all snakes are venomous. The composition of the venom and its quantities vary from species to species. In general it is a complex mixture of proteins which can be categorized according to the organs they attack i.e. neurotoxic (attacks the nervous system) or haemototoxic (attacks the circulatory system). Depending on their ability to kill their prey and the composition of venom they possess, snakes have been grouped in to four categories i.e. deadly venomous, moderately venomous, mildly venomous and non-venomous.
Can you identify them? Saw scaled viper and Gamma cat snake
Which one is deadly?
3. Identification of Venomous Snakes
Russell’s viper and Pythons
20 In the animal world, different species use various techniques to survive. These include their need to find food and defense mechanisms geared to combat predation. Snakes have the ability to do this quite successfully, even to the extent of deceiving us human beings.
3.1 Mimicry The most common mechanism used by snakes is called mimicry. Where non-venomous species mimic or superficially look like (casually resemble) a venomous snake, it serves as a warning to others, especially their predators, that they are venomous and must be avoided.
Only one from these three are deadly venomous, which one is it?
Kraits and Wolf snakes
15
Although these species look quite similar, not all of them are venomous because the non-venomous ones mimic the venomous ones i.e. harmless species mimic the colour patterns of deadly venomous snakes.
4. Kraits In Sri Lanka, there are two species of Kraits, the Indian krait and the Ceylon krait. They are both deadly venomous. Interestingly, there are six harmless species that mimic these kraits, including wolf snakes and bridal snakes.
24
Both snakes shown above display a common form of behavior seen among snakes, whereby they conceal their heads under their bodies as a defense mechanism. Above: Indian krait that is deadly venomous. Below: Sri Lanka wolf snake which is a non venomous species.
The best and the easiest character that can be used to differentiate the venomous Kraits from the non-venomous mimics is the dorsal scale row shown in the figure below.
Venomous Kraits
Non - venomous mimics
Large hexagonal scales running down the spine
All scales on back identical in size
Prominent white cross bars in a juvenile.
Simple identification character: Large hexagonal shaped scales running down its spine. Scales on its back are smooth, with the mid row much larger than all the other surrounding scales. This feature is the most important characteristic when identifying the species. Adult specimen, where the cross bars or white lines have reduced and scattered.
4.1 Bungarus caeruleus Indian krait (E);Thel karawala (S) 26
Toxicity: Deadly venomous Size: 25 cm- 140 cm Colouration: Back bluish black to a pale faded bluish grey, with white cross bars occurring in pairs which become less distinct at the anterior end. These cross bars are prominent in juveniles or young animals and the lines gradually disappear or become reduced to scattered cross bars in adults. The ventral side, or the underside is off-white.
Left: Clear pairs of cross bars of a juvenile. Right: The cross bars gradually diminishing in adults. But both show enlarged hexagonal scale rows along the spine.
Distribution: Non-endemic. Distributed in the dry, arid, and intermediate zones. Behavior: : It is a nocturnal species that is aggressive at night. Commonly found in and around human settlements. May attack if threatened but generally nonaggressive during day time. Will roll into a ball with its head well-concealed when agitated, and might spring out from this position upon further agitation. Feeds on: Other snakes, geckoes, lizards, rodents etc. Reproduction: They lay 10- 16 eggs per clutch.
4.2 Non venomous species that mimic the Indian Krait Three harmless Wolf snakes mimic the Indian Krait.
Juvenile specimen.
Scales on the back are all identical, and smooth. The subcaudal scales on the underside on its tail are all divided.
Distribution: Non-endemic. Distributed in all parts of the island up to 2000 m asl. Commonly found in rural areas close to forests, in houses (especially among piles of wood, piles of stone, foundations and walls where there are plenty of cracks/crevices), stacked bricks, piled up coconut leaves, and coconut roots etc.
Adult specimen.
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4.2.1 Lycodon aulicus Wolf snake, House snake (E); Alu radanakaya (S)
Behavior: : It is a nocturnal species that is aggressive at night and attacks fiercely. Will roll in to a ball with its head well concealed when agitated, and empty their bowels with a smell similar to that of rotten dead mice (hence the Sinhala name “Kunu mee karawala”) as a defense mechanism. Feeds on: Geckoes, lizards, small rodents etc. Reproduction: They lay about 20 eggs.
Toxicity: Non venomous Size: 18 cm- 80 cm Colouration: Back dark brown to blackish brown, with white cross bars that divide laterally which are prominent in the anterior end. These cross bars are prominent in juveniles and young, and the lines gradually disappear or become reduced to scattered cross bars in adults. Lips are prominently white, while the ventral or underside is off-white.
Distribution: This species is endemic to Sri Lanka. Distributed in all parts of the island up to 2000 m asl. It is commonly found in urbanized and semiurbanized areas, in houses (especially under flower pots, piles of stone, loose soil, in foundations and walls where there are plenty of cracks/crevices), stacked bricks, piled up coconut leaves, coconut roots, piles of wood and in piled up goods such as clothes, books, boxes etc. Behavior: It is a nocturnal species that is aggressive at night and attacks- and bites fiercely. Will roll in to a ball with its head well concealed when agitated, and empty their bowels with a smell similar to rotten dead mice. Hence, in Sinhala, it is called “Kunu mee karawala”, owing to the particularity of its defense mechanism. Feeds on: geckoes, lizards, small rodents etc. Reproduction: They lay 8-10 eggs per clutch.
4.2.3 Lycodon striatus Shaw’s wolf snake (E); Kabara radanakaya (S)
4.2.2 Lycodon osmanhilli Flowery wolf snake (E); Mal radanakaya (S)
Toxicity: Non venomous 30
Size: 15 cm- 60 cm Colouration: They show two variations in colour. One morph has a light brown to a yellowish tinge, with divided yellow cross bars throughout its back. The other has a uniform light brown coloured body with no white markings on the back. In both cases the head colouration is light brown with a yellowish tinge. Eyes black and prominently seen because of the lighter skin colour compared to others, with white lips upon which every lip scale has a brown mark in the center. Scales on the back are all identical, and smooth. The subcaudal scales on the underside on its tail are all divided.
Toxicity: Non venomous Size: 9 cm- 28 cm Colouration: The back is dark brown to blackish brown in colour, with white cross bars which are prominent at the anterior end that divide laterally and are broken. In some, these cross bars are yellow. Its lips are white, however not as distinctly as L. aulicus.The ventral or the underside is off-white. Scales on the back are all identical, and smooth. The subcaudal scales on the underside on its tail are all divided.
Distribution: Non-endemic. Distributed in all parts of the island up to 2000 m asl. Commonly found in houses (especially in piled up goods, in home gardens, mounds of stone, foundations and walls where there are plenty of cracks/crevices), stacked bricks, piled up coconut leaves, coconut roots, and piles of timber etc. Behavior: It is a nocturnal species that is non-aggressive and does not attack. Will roll in to a ball with its head well concealed when agitated. Feeds on: Small skink and lizards. Reproduction: They lay 5-6 eggs per clutch.
An adult specimen showing the typical banding pattern and enlarged scale row on the spine.
4.3 Bungarus ceylonicus Sri Lankan krait (E); Mudu karawala (S) Toxicity: Deadly venomous Size: 100- 110 cm
32
Colouration: Back jet black, with white cross bars. These cross bars are prominent in juveniles/young and the lines gradually disappear or become reduced to scattered cross bars in adults. Ventral or the underside is black or alternately black
Juvenile specimen with prominent white cross bars. The posterior half of the head is white coloured.
and white. Posterior half of the head in juveniles is white. However the white colour diminishes gradually with age.
Simple identification: Large hexagonal shaped scales running down its spine. Scales smooth on back. They are much larger than all the other surrounding scales.
4.4 Non venomous species that mimic the Sri Lankan Krait There are three harmless snakes (Sri Lankan wolf snake and two bridal snakes) that mimic the Sri Lankan krait.
Left: Faded white cross bars in an adult. Right: Prominent white cross bars in a juvenile.
Distribution: Wet, intermediate and rarely seen in the dry zone.
34
Behavior: It is a nocturnal species that is aggressive at night. Commonly found in and around human settlements. Potentially non-aggressive in nature, but may attack if provoked or threatened. Will roll in to a ball with its head well concealed when agitated, and will remain still until the perceived danger passes. They display this behavior much better than the Indian Krait. Feeds on: Other snakes, geckoes, lizards and rodents etc.
An adult specimen.
4.4.1 Cercaspis carinata Sri Lanka wolf snake (E); Dhara radankaya (S)
Reproduction: They lay 6-10 eggs per clutch. Toxicity: Non venomous Size: 65 cm Colouration: Head jet black and shiny, the body is black with white cross bars. These cross bars are prominent in juveniles/young and as they become adults the lines gradually disappear or become reduced to scattered cross bars. Ventral or the underside is black or alternately black and white. Posterior half of the head in juveniles is white and gradually diminishes with age.
A Juvenile specimen showing prominent cross bars and the posterior part of the head is white coloured.
Simple identification: Scales on the back are deeply ridged, keeled or rough, a character evident only in this species out of those that mimic kraits. Scales on its back are all identical, and deeply ridged. scales on the underside on its tail or subcaudal scales are all single or undivided.
36
4.4.2 Dryocalamus nympha Bridal snake (E); Geta radankaya, Geta karawala (S)
Distribution: Found only in the wet zone.
Toxicity: Non venomous
Behavior: It is a nocturnal species that is aggressive at night. Commonly found under leaf litter of the forest floor and in home gardens close to forests. May attack if provoked or threatened. Will roll in to a ball with its head well concealed when agitated, and will remain the same till the perceived danger passes.
Size: 70 cm
Feeds on: Geckoes, lizards, skinks, small rodents and rarely on other snakes etc. Reproduction: They lay 8-12 eggs per clutch.
Colouration: The back of the animal is black with white cross bars which may be yellowish in juveniles. These cross bars are prominent in juveniles/young and the lines gradually disappear or become reduced to scattered cross bars in adults. Posterior cross bands are connected laterally. Ventral or the underside is white. Simple identification: Possesses a comparatively larger head with a slimmer neck area. Its body is adapted to climb trees, with a long tail and prominent ventral ridges on either side. Scales on the back are all identical and smooth. Underside scales on tail or the subcaudal scales are all divided.
Distribution: Found in the dry and intermediate zones. Behavior: It is a nocturnal non-aggressive species. Commonly found in large tree trunks and under debris, in and around home gardens or human settlements. Will roll in to a ball with its head well concealed when agitated.
5. Vipers
Feeds on: Skinks and eggs of geckoes etc. Reproduction: They lay eggs. But the number is not known, but a gravid female specimen with 5 eggs (upon external observation) has once been recorded.
Sri Lanka has two species of true vipers (Russell’s viper and Saw scaled viper). They are both deadly venomous, but very often people get these confused with non-venomous pythons.
4.4.3 Dryocalamus gracilis
The best and the easiest characters to discriminate the venomous Russell’s viper from the two non-venomous pythons (Rock python/ Indian python and Sand Boa) are listed in the table below.
Scarce bridal snake (E); Meegata radankaya (S)
Distinguishing characters
A preserved museum specimen of Scarce bridal snake which was used to describe the species scientifically, deposited at the Natural History Museum London.
Russell’s viper
Rock Python
Sand Boa
Markings on back
Regular, oval
Irregular, cloud shaped
Irregular, cloud shaped
Distribution of scales on head
Large number of small sized scales
Both large and small sized
Small sized, large number
Head scales
Rough
Smooth
Rough
Snout shape from top
Comparatively pointed
Blunt
Blunt
Labial pits
Absent
Present
Absent
Mid body scales on back
Rough/keeled
Smooth
Smooth
Tail scales on back
Rough/keeled
Smooth
Rough/keeled
Sub-caudal/under side of tail scales
Divided
Single
Single
Vestigial hind limbs
Absent
Present
Present
Distribution
< 2000 m asl
< 2000 m asl
Arid zone and coastal dry zone
Toxicity: Non venomous 38
Size: 50 cm Remarks: A very rare species, only known from a single record. Colouration: Back, black with white cross bars. Similar to Dryocalamus nympha. Simple identification: Can only be separated by Dryocalamus nympha, by the number of costal scales. Where D. nympha, has 13 scales and D. gracilis has 15 scales. Distribution: Single record from Colombo, wet zone. Behavior: Unknown
Feeds on: Unknown
Reproduction: Unknown
The row of spots on back of a Russell’s viper which are comparatively large and oval shaped outlined with a black line, with its outer border whitish.
Simple identification: From the large oval spots that run down the body, and the keeled costal scales. The pair of scales over the eye or the supra ocular, and the supra nasal scales are large. This species can be identified from its loud hissing noise.
5.1 Daboia russelii Russell’s viper (E); Thith polanga (S)
Toxicity: Deadly venomous 40
Size: 120-130 cm Colouration: Earthy brown with three rows of dark brown spots on the back, one running down the spine and the other two on the sides of body. The row of spots on its back are comparatively large and oval shaped, outlined with a black line, with its outer border whitish, while those found on the lateral body are small and somewhat oval. On its head a pair of dark brown patches forms a light brown ‘V’ pointing toward the snout. Ventral or the underside is off white with black or dark brown blotches.
Head close up of Russell’s viper showing a pair of dark brown patches, which forms a light brown ‘V’ pointing toward the snout.
Distribution: Found both in the wet and the dry zones < 2000 m asl. Behavior: It is a nocturnal species that is aggressive at night. Commonly found in forests, in and around human settlements, paddy fields, under piled-up goods, and coconut husks etc. If provoked or threatened, it will coil and raise a third of its body and produce a loud hissing noise which is the loudest of all snakes.
Feeds on: Adults feed on rodents and birds, while juveniles may feed on geckoes, lizards, frogs etc. Reproduction: They give birth to 30-35 live young.
5.2 Non venomous species that mimic the Russell’s viper
Toxicity: Non venomous Size: Female-100 cm, males-60 cm Colouration: Earthy brown with large dark brown blotches on back which are connected but may be separated. Much smaller blotches are found on the side of its body, which are randomly distributed. Ventral or the underside is pinkish in colour.
The two non-venomous pythons (rock python and sand boa) superficially look a lot like a Russell’s viper. Out of which the sand boa is more similar but is less commonly found.
5.2.1 Eryx conicus Sand boa (E); Wali pimbura, Kota pimbura (S) Mid body colour pattern of a Sand Boa.
Simple identification: Smooth mid body scales, and the blotches on its back. Scales on the back of its tail are deeply ridged (keeled/rough) The subcaudal scales on the underside of its tail are single or undivided.
43
A close up view of the head of a Sand boa showing its rough and small even sized scales.
Distribution: Found only in the coastal dry zone and arid zone. Behavior: It is a nocturnal species that moves slowly and is lethargic. It is rare but can be found burrowed within soil in dry and arid parts of the island. They constrict their prey to immobilize them. Feeds on: small mammals, geckoes, lizards, skinks, frogs etc. Reproduction: They give birth to live young.
5.2.2 Python molurus
Large sized blotches on mid body.
Rock python (E); Dara pimbura, Ran pimbura (S)
Simple identification: The pattern of blotches on its body. The subcaudal scales on the underside of its tail are single or undivided.
44 Close up of head showing the markings of an arrow pointing towards head, and scales of different sizes.
Toxicity: Non venomous
Distribution: < 2000 m asl
Size: 600 cm
Behavior: A slow moving nocturnal species, but if threatened will move fast to hide. If threatened they will also coil and warn by hissing several times before attempting to bite. It is a highly camouflaged species that lives amongst leaf litter, and well-adapted as an ambush predator. Uncommon but can be found in forests, and in semi-aquatic environments. It is also well-adapted to climb trees. They constrict their prey to immobilize them.
Colouration: Whitish or yellowish with three rows of large sized blotches on back. Colours vary from a light brownish tinge to a dark brown. The row of blotches on the back is much larger than the rows on the side of body. Ventral or the underside is cream with small dark brown or black spots.
Toxicity: Deadly venomous
Size: 30-40 cm
Colouration: Light brown or pale earthy brown with a series of dark brown spots outlined with whitish lines on back. On its head there is a distinct off-white marking which may look like an arrow, or the foot print of a bird, or a crucifix. Ventral or the underside is off white to light brown, with small dark brown spots. The vestigial hind limbs of Python mollurus (Rock Python).
Feeds on: Large to small mammals (except those that are carnivorous and very large species), flying mammals, small sized crocodiles, land monitors, birds etc. They constrict their prey to immobilize them. Reproduction: They lay 12- 40 eggs, and are the only snakes in Sri Lanka that protect and incubate their eggs.
5.3 Echis carinatus Saw scaled viper (E); Wali polanga (S)
Distinct marking on the head of Saw scaled Viper, which may look like an arrow, a foot print of a bird or a crucifix.
Simple identification: The off-white distinct marking on the head. Costal scales are keeled/rough and identical in size except for the pair just above the eye (supra ocular) and inter-nasals, which are smooth and larger in size. The subcaudal scales on the underside of its tail are single or undivided. 46
Distribution: Found in the arid and the coastal dry zone. Behavior: It is an aggressive nocturnal species that is rarely diurnal. When threatened they coil and make a small warning noise by rubbing their body coils against each other. It is a highly camouflaged species in its natural habitat which is sand-mixed dry leaf litter. Potentially aggressive and will attack if provoked. Has limited distribution, hence uncommon but commonly found in its preferred habitat, the sand dune forests and surrounding home gardens. During the dry season, they are commonly seen under palmyrah leaves (Borassus flabellifer), which have fallen close to wells and places where there is water. Feeds on: Geckoes, lizards, frogs, small rodents etc. Reproduction: They give birth to live off spring.
5.4 Non venomous species that mimic the Saw scaled viper 5.4.1 Boiga triginata
Toxicity: Non venomous Size: 70-100 cm Colouration: Light brown or pale earthy brown with a series of off white ‘V’ shaped markings outlined in dark brown or black running down its spine. On its head there is a distinct off whitish ‘Y’ shaped marking. Ventral or the underside is light yellow, with small dark brown spots on either side.
Gamma cat snake (E); Garandi mapila, Ran mapila, Kaeta mapila (S)
Distinct ‘Y’ shaped marking on the head of a Gamma cat snake.
48
Simple identification: The off whitish distinct ‘Y’ shaped marking on head. Underside scales on tail or subcaudal scales are divided. Distribution: Found in the arid, dry and intermediate zones. Behavior: It is a nocturnal species. When threatened they make a warning noise by patting its tail on to a surface. Non aggressive, and can be commonly found on trees, piled up goods, and in and around human settlements etc. Feeds on: geckoes, lizards, skinks, small birds, small sized bird’s eggs, small rodents etc. Reproduction: They lay 8-12 eggs per clutch.
6. Cobra
Toxicity: Deadly venomous
There is only one species of cobra (Indian cobra or Spectacled cobra) found in Sri Lanka. It is a deadly venomous species, and is the most commonly known venomous snake, amongst people in the island.
Colouration: The colour on its back varies from dark brown to dark reddish brown or dark grey to grayish black with white or light yellow cross bars. These cross bars are either incomplete or complete with sets of four to six bands grouped at times. Hood contains a large usually white-coloured spectacle shaped marking, and the surrounding area is reddish. The ventral or the underside may vary from white to pale yellow to light brown, while some may have a single colouration, others may have cross bars or blotching.
6.1 Naja naja
Size: 180 cm
Indian cobra, Spectacled cobra (E); Naya, Nagaya (S)
50
The prominent, large spectacle shaped marking on the hood of a cobra which is commonly white.
Simple identification: It forms a distinctive hood, raising its body and displaying the prominent spectacle shaped marking on the head. When the hood has not expanded, the easiest way to identify this snake is by the observing its rostral scale, the area below the eye which is outlined in black. The subcaudal scales on the underside of its tail are divided.
Distribution: < 2000 m asl. Behavior: It is a diurnal species that is rarely nocturnal (but large sized cobras may be encountered at night very rarely). Commonly found in and around human settlements, paddy fields, under piled-up goods, piled-up coconut husks etc. A potentially non-aggressive species, but if threatened or provoked will expand its hood and warns by its fake attacks. Feeds on: Small mammals, frogs, lizards, monitors, other snakes, birds and their eggs etc. Juveniles may consume skinks, geckoes etc.
Literature cited 1.
Smith, E., Manamendra-Arachchi, K. and Somaweera, R. (2008). A new species of coralsnake of the genus Calliophis (Squamata: Elapidae) from the Central Province of Sri Lanka. Zootaxa. 1847:19–33.
2.
Wickramasinghe, L.J.M., Vidanapathirana, D.R., Wickramasinghe, N. and Ranwella, P.N. (2009). A New Species of Rhinophis Hemprich, 1820 (Reptilia: Serpentes: Uropeltidae) from Rakwana massif, Sri Lanka. Zootaxa. 2044: 1–22.
3.
Maduwage K., Silva A., Manamendra-Arachchi K. and Pethiyagoda R. (2009). A taxonomic revision of the South Asian hump-nosed pit vipers (Squamata: Viperidae: Hypnale). Zootaxa. 2232:1–28.
4.
Gower, D.J. and Maduwage, K. (2011). Two new species of Rhinophis Hemprich (Serpentes: Uropeltidae) from Sri Lanka. Zootaxa. 2881: 51–68.
5.
Wickramasinghe, L.J.M., Conservation Status of the Reptile Fauna of Sri Lanka. The 2012 Red List of Threatened Fauna and Flora of Sri Lanka. (Un der review)
6.
de Silva, P.H.D.H. (1980). Snake Fauna of Sri Lanka – with special reference to skull, dentition and venom in snakes. National Museums of Sri Lanka. Colombo. xi + 472 pp.
7.
Das, I. and de Silva, A. (2005) A photographic guide to snakes and other reptiles of Sri Lanka. New Holland publishers (UK). 144 pp.
8.
Somaweera, R. (2006) Sri Lankawe Sarpayin [in Sinhalese; “Snakes of Sri Lanka”]. WHT Publications, Colombo, Sri Lanka x + 297 pp.
9.
Rooijen, J.V. and Vogel, G. (2008). An investigation into the taxonomy of Dendrelaphis tristis (Daudin, 1803): revalidation of Dipsas schokari (Kuhl, 1820) (Serpentes, Colubridae). Contributions to Zoology. 77(1): 29–39.
Reproduction: They lay 20-40 eggs per clutch. Remarks: Juvenile cobras could be confused with juvenile rat snakes.
People often get confused between the more widespread and harmless Rat snakes with cobras. The rat snake plays a very important role as a pest controller.
52
A close-up view of the head of a Rat Snake showing black lines outlined on scales bordering the lip, which is the simplest feature that can be used for identification of rat snakes.
10. Vogel, G. and Rooijen, J.V. (2011). A new species of Dendrelaphis (Ser pentes: Colubridae) from the Western Ghats – India. Taprobanica. 3(2):77–85.
11.
De Silva, A., Wijekoon, A.S.B., Jayasena, L., Abeysekera, C.K., Bao, C.-D., Hutton, R.A. and Warrel, D.A. (1994). Haemostatic dysfunction and acute renal failure following envenoming by Merrem’s hump-nosed viper (Hypnale hypnale) in Sri Lanka: first authenticated case. Transactions of the Royal Society of tropical Medicine and Hygiene. 88: 209–12.
12.
Premawardena, A..P., Gunathilake, S.B. and de Silva, H.J. (1996). Haemostatic dysfunction following Hypnale hypnale bites. X1V International congress for Tropical Medicine and Malaria,Nagasaki, Japan. 17– 22.
13.
Sellahewa, K. (1997). Lessons from four studies on the management of snake bite in Sri Lanka. Ceylon Medical Journal. 42: 8–15.
14.
Kularatne, S.A.M. and Ratnatunge, N. (1999). Severe systemic effects of Merrem’s hump nosed viper bite. The Ceylon Medical Journal. 44(4): 169–170.
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Ariaratnam C.A., Thuraisingam, V., Kularatne, S.A.M., Sheriff, M.H.R., Theakston, R.D.G., de Silva, A. and Warrell, D.A. (2008). Frequent and potentially fatal envenoming by hump-nosed pit vipers (Hypnale hypnale and H. nepa) in Sri Lanka: lack of effective antivenom. The Royal Society of Tropical Medicine and Hygiene. 102: 1120–1126.
16.
de Silva H.J., Fonseka M.M.D., Gunatilake S.B., Kularatne S.A.M. and Sellahewa K.H. (2002). Anti-venom for snakebite in Sri Lanka. The Ceylon Medical Journal. 47(2): 43–45.
17. Whitehall, J.S., Yarlini., Arunthathy., Varan., Kaanthan., Isaivanan. and Vanprasath. (2007). Snake bites in north east Sri Lanka. Rural and Remote Health. 7: 751 1–6. 54
18.
de Silva, A. and Ranasinghe, L. (1983). Epidemiology of snakebite in Sri Lanka. Ceylon Medical Journal. 28:144–54.
19.
Seneviratne, U. and Dissanayake, S. (2002). Neurological Manifestations of Snake Bite in Sri Lanka. Journal of Postgraduate Medicine. 48: 275–279.
20.
Rajapakse, L., (2012) ‘Alarming increase in road accident, deaths, Island, 9 April (Online). Available at: http://www.island.lk/index. php?page_cat=article-details&page=article-details&code_title=49371 (Accessed: 6 December 2012).