326th Meeting – Tuesday, September 14th 2010

Hunting Northern Thailand’s Snakes on a Motorbike

A talk and PowerPoint presentation by Sjon Hauser


Present: Peter Kouwenberg, Marie and George Bedell, C. Michelson, Eric and Ketsanee Danell, Alex Brodard, Daniel Bellamy, Paisal Iriso, Klaus Berkmüller, Carol Beauclerk, David Steane, Etienne Daniels, Layle and Spencer Wood, John Cadet, Hans Bänziger, Anja Rohde, Jennifer Davis, Pierre Mangeot, Oliver Hargreave. An audience of 21. 


This talk on snakes in northern Thailand was based on the presentation of ninety images, none of which, unfortunately, we are able to present to you in this summary, but all of which are in Sjon’s new book.


Sjon’s commentary:

001 This first picture shows a cartoon adapted from Gary Larson’s The Far Side: holding a little snake in his hand, a western man is chasing his terrified wife in the garden. It expresses well that snakes are generally considered as horrible and frightening creatures. The commentary reads: ‘And for the rest of his life, the young snake suffered deep emotional scars.’ The empathy for the snake’s fate is unexpected and experienced as funny, which actually reaffirms that snakes are dreadful and the embodiment of evil.

002    Both in the West and the East, including northern Thailand, this negative attitude is predominant. It is also expressed in traditional culture. This picture shows a detail of a 19th-century mural in Wat Phumin, Nan, in which giant snakes are devouring human sinners in the Buddhist hell.

003    In a mural from Chiang Mai’s Wat Umong Maha Thera Chan, a banded krait and a cobra are seen in the frontlines of Mara’s army, attacking the Buddha who is on the verge of attaining enlightenment, while the Mother of Earth has begun wringing the water from her hair — Mara’s forces of Evil will drown in the resulting tsunami.

004    Images of nagas (mythological serpents) protecting the meditating Buddha can be seen everywhere in Thailand. This large image is on a hill top at That Ton, along the Mae Kok River. In Buddhist scriptures nagas are devout and pious creatures, yet in popular culture their ferocious character is usually emphasized. The nagas living in the Mekong River have the notorious reputation to electrocute their victims and to suck their blood until the corpses are completely devoid of a single drop.

005    Although cars are certainly more dangerous than snakes, few persons will yell when spotting one. Yet, a tiny innocent snake may stir a commotion.

It is true that bites from certain snakes may result in serious envenomation. It should be realized that many bites are inflicted when persons chase and try to kill a snake. Annually, no more than 300 persons are killed by snake bites in Thailand.

On the other hand, every day thousands of snakes are killed on roads by cars and motorbikes alone. This picture shows an Indochinese rat snake (Ptyas korros) bleeding from the mouth after it was hit by a car. Lucky enough it had risen the upper part of its body when sensing the approaching speeding vehicle — that saved it from being run over. This relatively large snake is one of the more common species in Thailand. Note the uniformly light-brown back and the yellowish belly.

006    A picture of another Indo-Chinese rat snake, a sub-adult specimen with large melancholic black eyes, freshly killed on the ‘death highway’ from Tak to Mae Sot, the tongue drooping from the mouth.

My interest in snakes began about ten years ago, when crossing the country on a motorbike. I was surprised by the large number of snake roadkills. They enabled me to have a close (and safe) look at snakes. Often I found it difficult to identify them with the help of available literature on Thailand’s snakes. Gradually I learned more about Thai snakes, and about the horror on Thai roads.

007    Another picture showing a pitiful roadkill. The beautiful sunbeam snake (Xenopeltis unicolor) is a very common nocturnal snake. This snake is from Loei province, in the northeast. Its lower part was run over by a vehicle; in the agony of death the snake attacked its own body. I found the dead snake in this posture on the tarmac in the early morning.

Roadkills can teach us a lot about snakes, because they are abundant and allow us to carefully inspect them. On the other hand, when you spot a living snake in the wild, it will usually flee and disappear in a wink of the eye, so good observation is virtually impossible.

008    The picture of a brownish snake is shown for a split second, and the audience is asked to guess what kind of snake it is. As the animal had its body raised, some persons suggested that it might be a cobra or king cobra, one single guess was ngu kapa (Malayan pit viper).

Besides the problem of identifying snakes during the brief encounters, snake enthusiasts will learn that identifying snakes can be difficult for some other reasons.

009    A textbox summarizing some basic facts concerning snakes: About 3000 species are known worldwide, of which more than 180 occur in Thailand (including sea snakes in coastal waters). I have found over eighty species in the North (including the ‘Lower North’). Doi Suthep hosts over 50 species, while in the city of Chiang Mai at least twenty different species can be spotted. Snakes are abundant in most ecosystems, such as marshes, rivers, the sea and other waters, grasslands, forests, wastelands, agricultural lands, orchards and gardens, and occasionally they even live in houses.

010    Despite this abundance we see relatively few snakes. Some reasons for this are summarized in a textbox: 1. many have cryptic colours, 2. many are hidden in crevices and holes, 3. many live in the soil or forest litter, 4. many are secretive and very shy, 5. many are nocturnal. In this picture a snake with amazingly cryptic colours is hidden, do you see it?

011    The same picture is shown, now rotated 180 degrees. The snake in the leaf litter of a deciduous forest is a Malayan pit viper (Calloselasma rhodostama). Its brownish body with dark brown triangles makes it very difficult to spot.  This pit viper is common at the lower elevations of Doi Suthep and many other places in the north. It is one of the most dangerous snakes in the region, and therefore I will elaborate upon it. It has a characteristic rhomboid-shaped head. In Thailand it is called ngu kapa, ‘kapa’ is Malay for the iron blade of an axe. It is called a pit viper, because of the presence of a heat-sensitive pit-organ, the entrance of which is clearly visible between the eye and nostril. It has large movable fangs suspending from the palatum, but when it opens the mouth, the fangs are rotated to a position ready to bite. Thai sometimes refer to this snake as ngu kradueng (‘rattlesnake’). It has no rattle-organ like true rattlesnakes, but it can produce a buzzing sound by vibrating the tail. Although this is a ‘killer snake’, few Thai and foreigners know it or can identify it.

012    A picture of two young men at the gate of my house, one carrying a plastic bag. They bring me a snake, which was caught by a drunken man at Huai Kaeo Falls at the foot of Doi Suthep. No one at the picnic knew what kind of snake it was. The snake was a Malay pit viper, a fully grown adult. This snake is easily provoked to strike and the fangs could have punctured the bag—the guys were lucky that nothing of that kind had happened.

013    A picture of this snake in a terrarium, holding a large mouse in its mouth. It always had a good appetite, detecting the presence of living prey instantly and striking as soon as the mouse came within striking distance. Usually a mouse died within ten seconds. So the venom (predominantly haemotoxins) is very potent, and usually a considerable amount is injected.

014    This may happen when it bites your hand. The picture shows an arm covered in large, dark blisters of a person bitten in the hand by a Malayan pit viper. Serious tissue necrosis may result; often limbs need to be amputated. Complications lead to many fatalities. In some parts of Cambodia more limbs are amputated of victims of these snakes than of victims of landmines. In Cambodia this pit viper is common and the number one killer among the snakes. In southern Thailand the snake can be abundant in rubber plantations. When collecting the latex at night, workers in the plantations wear rubber boots to prevent accidents.

A local case: An Akha man from a village in Mae Taeng district, Chiang Mai, spotted a snake that was guarding a clutch of eggs on the forest floor. He tried to catch the animal, but was bitten. Yet, he succeeded to kill the snake and to return to his village. No villager had seen such a snake before. The man’s arm was painful and swollen, twice its normal size. He was treated with herbs by a local healer, but he was afraid to die. No attempts were made to send him to a hospital. In three days the arm had retained more or less its normal size. The snake had been eaten by the villagers. It was, almost certainly, a Malayan pit viper. Probably the bite was superficial. Were it a deep bite with the injection of much venom, the outcome could have been very different. Many snake bite fatalities in similar context will go unreported.

Local knowledge (‘wisdom’) is surprisingly poor with regard to snakes. I believe that some basic knowledge about snakes can save human lives, as well as thousands of harmless snakes now killed as they are supposed to be deadly.

015    An example of the prevailing rampant ignorance concerning snakes. A picture is shown of a little Assamese mountain snake (Plagiopholis nuchalis), a fresh roadkill from the mountains of Mae Taeng district. This snake has a characteristic chevron, shaped like an arrowhead. It is common in evergreen forests at elevations of over 700 m where hunts earthworms in the forest litter. I found this specimen in front of the home of villager, who was alerted by my presence—a stranger scavenging on the tarmac. When I showed him the snake and asked him what kind it was, he answered: ngu chong ang, a king cobra! This is a far cry from ‘local wisdom’, as the neonates of the much feared king cobras are already double the size of this little Assamese mountain snake and have many characteristic cream cross-bands!

This transgression on one particular, dangerous snake and on the general ignorance about snakes, had followed my remarks about cryptic colours making snakes difficult to spot.

Another reason for encountering relatively few snakes is that numerous species are fossorial (= living in the soil, or at least deep in the leaf litter) and seldom leave this microhabitat.

016    A good example of a fossorial snake is this little one, the collared reed snake (Calamaria pavimentata). One seldom comes across it, neither in the forest, nor as a roadkill, but hill tribes often bring them to the light when digging in their swiddens. This is a very small snake, not growing longer than 35 cm.

017    The blind snakes are even smaller and more fossorial. This is a picture of the relative large Diard’s blind snake (Typhlops diardii), but the most common blind snake is the ‘flowerpot snake’ (Ramphorhynchus braminy), which looks similar, like a dark earthworm. Snakes probably descended from fossorial lizards, losing their limbs and much of their eyesight in the course of the evolution. Jacobson’s organ developed as their most important sense, a kind of ‘second smell’. The flowerpot snake is probably a bit similar to the primitive snakes of the past. They are very common, feeding on ants, termites and other insects, including their larvae and eggs. When digging in your garden and removing soil to get rid of the roots and stump of a felled tree you may come across them. One or even more specimens may be present in a cubic metre of soil. But they are rare as roadkills because they seldom leave the soil (they do sometimes following heavy rains).

018    You are more likely to find a flowerpot snake on the road like this. A MacClelland’s coral snake (Sinomicrurus macclellandi) that had devoured a flowerpot snake, was run over by a car, the flowerpot snake popping out of the bowels of the roadkill. The venomous, semi-fossorial coral snakes often prey upon blind snakes, as do a number of other snakes.

The flowerpot snake is unique among snakes: it is parthenogenetic, only females exist, of which the eggs develop without being fertilized by the sperm of the (non-existent) males. Therefore, it needs only one specimen (e.g. hidden in the soil of a flowerpot) to establish a new population. Beside South and East Asia, the tiny snake’s feminist’s utopia already has conquered large parts of the Middle East, Africa, and tropical America, including Florida — hidden in the earth.

019    This is a better picture of the beautiful brick red MacClelland’s coral snake. It has potent venom, but a rather gentle disposition towards humans. This individual was spotted on Doi Suthep near the Phu Phing Palace, and you will probably not find it in Chiang Mai Valley (instead, a smaller relative, the small-spotted coral snake, occurs in lowlands).

Many snakes have bright colours and conspicuous patterns which seem to be not cryptic at all. Why? One possible function of bright colours is to scare off potential predators, especially when combined with some kind of display, such as enlargement of the body, or the rising of the tail.

020    Displaying the tail and forming a circle with it, is a characteristic defense posture of the MacClelland’s coral snake. So you are warned!

021    Cryptic colours and bright warning colours can be combined in the same species. The common red-necked keelback (Rhabdophis subminiatus) has a very conspicuous scarlet neck. The specimen in this picture is hiding in a crevice in an earth dike along the road after I had chased it away from Highway 108 in Hot district. It is carefully concealing the conspicuous red neck behind the head and body coils.

022    In this picture you see the same specimen after I had noticed it crossing the road. Alerted by my approach, it expanded its body: the bright, red neck is especially conspicuous, but also the rest of the body is eye-catching — a white pattern of the now exposed edges of the scales is visible. The snake’s appearance is very different compared to the previous picture.

I have saved the life of dozens of snakes crossing roads and therefore I permit myself once in a while to catch a snake to keep in a terrarium. But I was not interested in this beauty, as its bite can be deadly, and I wish to keep a smooth relationship with my neighbours—snakes are masters of escape.

Until a decade ago, it was sometimes not realized that bites from this snake may result in serious envenomation; in one website it was even labeled as harmless. As it belongs to a family of predominantly harmless snakes (the Natricidae, to which also the European ring grass snake belongs) it was not suspected of producing potent venom. This only came to light after the pet trade had brought it to the USA. In general, it does not strike and bite easily, but ill-tempered specimens that do can inject much venom while chewing in the flesh. A few persons have succumbed to such bites.

Briton Reginald Le May came across a red-necked keelback along the Mekong River in Chiang Rai while crossing the North on an elephant early in the 20th century (An Asian Arcady, 1926). Interestingly, local villagers told him that its bite was deadly. This suggests that local wisdom flourished in those days. However, it should be realized that many non-venomous snakes are also believed to be deadly, and such beliefs were probably also common in the past.

A number of related species may also produce potent venom, and now all members of the Natricidae are suspected. In his recent Field Guide to the Reptiles of Thailand and South-East Asia (2010), Indraniel Das plays safe by labeling all with a symbol denoting that ‘bites from small snakes may cause slight envenomation in humans, while bites from adults of some species can cause mortality’.

023    In this picture a red-necked keelback is swallowing a toad. I wish to thank Allan and Heather Ann Docherty for permission to show this fascinating picture taken on Doi Ang Khang. In general, snakes can be safely observed and photographed when swallowing prey. Identifying snakes from pictures can be treacherous. The neck of this individual has expanded so strongly that the characteristic bright red neck looks very different from the non-expanded neck, and initially I misidentified the snake.

024    The Oriental whip snake (Ahaetulla prasinum) is a good example of a snake of which the slender body and its colour are very cryptic. It is difficult to spot it when hidden in bamboo, reeds and bushes. It is very common in forests. This specimen was spotted in Pha Wa National Park in Tak.

025    During sunny days, this arboreal snake often descends to the forest floor and may be spotted crossing a road very slowly in a rectilinear mode of locomotion, the tongue sticking out almost continuously. This one was spotted on Doi Inthanon. Modern snakes, descended from primitive snakes with degenerated vision, have ‘re-invented’ the eye. The Oriental whip snake belongs to the few snake species with binocular vision, important in arboreal life. The long and grooved snout and the key-hole pupil make binocular vision possible. 

026    When cornered, the Oriental whip snake expands its body and throws it into loops. During such defensive display the colours and patterns of the skin beneath the scales are shown. Snake experts in India have emphasized its aggressive character, while those in Thailand consider it a docile animal. My experience is that the snake easily assumes a defensive posture, but will not easily strike from this position. This individual was spotted in Huai Nam Dang National Park.

027    Another aspect of this fascinating snake is its variable colour. This is pale green morph from Mae Takhrai National Park. Grey, yellow brown and ochre varieties are also known.

028    Juveniles are often ochre or orange brown. This juvenile was spotted in Mae On district, Chiang Mai.

029    The Oriental whip snake is virtually absent in the lowlands of Chiang Mai, but a close relative, the long-nosed whip snake (Ahaetulla nasutum), is quite common there. It is always bright green, as far as I know, and is very similar to a green morph of the Oriental whip snake. A nose-appendage, of which the function is not known, tells it apart from the latter.

030    These whip snakes are not the only ‘long, slender and green snakes’ in the north. Another green snake is the green trinket snake, a rather common mountain snake. This one is from Doi Ang Khang. Before 1998, identifying it could have been a problem, because it is not mentioned in the most popular works of those days. For example, it is absent in Merel Cox’ The snakes of Thailand and their husbandry (1991). The well-known Photographic Guide, a little green book published in 1998 by Cox et al. contains a good picture of the snake, described as Elaphe prasina and. In Lai ngu thai by Wirot Nutphan (2001) its scientific name is Gonyosoma prasina and the author believes it is a very rare snake. In a review article by David et al. (2004) its name is Gonyosoma prasinum, while it has been renamed Rhadinophis prasinus (English name: green trinket snake) in a Field Guide from 2010. Many snakes from the region have been renamed and relocated to other genera over the past two decades, resulting to numerous scientific names now in circulation for the same species. This may lead to further confusion when trying to identify a snake.

The green trinket snake also shows that northern Thailand has been somewhat neglected by Thailand’s snake experts.

031    Details of a green trinket snake from Chae Son National Park, Lampang. In contrast to the Oriental or long-nosed whip snake it has no pointed snout and no key-hole pupils. You will not come across it in Chiang Mai valley, as it prefers evergreen forests at higher elevations.

032    However, when you live at the edge of the valley, for example, near Huai Kaeo, Mae On district, another emerald green snake, one that can reach a length of  over 230 cm, may be spotted in your garden: it is the red-tailed rat snake (Gonyosoma oxycephalum), ngu kap mak in Thai. When annoyed, it inflates its neck by means of tracheal sacs that fill with air. Note the rusty tail. As with the green trinket snake it is non-venomous.

033    In this picture a red-tailed rat snake is flicking its metallic blue tongue.

034    At last, another green snake, the Pope’s pit viper (Popeia popeiorum, formerly known as Trimeresurus popeiorum), the most common of three green pit vipers occurring in the north. These are dangerous, venomous snakes, producing a rather strong venom containing both haemo- and neurotoxins. Though seldom deadly, the bite often leads to serious envenomation. These are rather slow-moving, arboreal and nocturnal animals with a triangular head and eyes with vertical pupils. Some specimens (the males) of the Pope’s pit viper have a red-and-white lateral stripe running from the head to the tail. The head is covered with many tiny scales (in contrast to a characteristic number of head plates in most other snakes). This snake prefers mountain forests, while a rather similar lowland green pit viper (the white-lipped pit viper) is uncommon in or absent from Chiang Mai Valley. The big-eyed pit viper is absent from the Upper North.

035    So, numerous ‘green snakes’ co-exist in the North. Of those mentioned, only the long-nosed whip snake is a probable visitor of your garden in Chiang Mai Valley. But another green snake is probably the most common green snake in or around your home… this is the golden tree snake (Chrysopelea ornata), a beautiful and agile snake and an excellent climber. It often enters homes to hunt for warm-blooded animals and geckos. This snake can make spectacular gliding flights (up to 50 m) by flattening its body and it is also known as the ‘flying snake’. The colour is green, but actually the scales are pale yellow with a black pattern.

036    Here you see the details of the black head with pale yellow crossbars of this snake. It will not hesitate to bite when you try to catch it. Though it is mildly venomous, the bite will usually not even result in swelling or other symptoms.

As there are many different green snakes, there are also numerous ‘brown snakes’, several ‘red snakes’, and number of ‘banded snakes’, etc. The only way to tell them apart is to learn their characteristics. I will now show pictures of some 20 snake species which are most common in and around Chiang Mai

037    In this picture of a condominium and adjacent houses in Chiang Mai the places are indicated where you can expect snakes (and what kinds): near and in waters, in bushes and trees, in gardens and fields, and in homes.

S038  The common bronzeback (Dendrelaphis pictus) is a very common, brownish bronze snake. It has a slender body with a copper head. It has a pronounced black lateral stripe.

039    When annoyed and expanding its body, the blue skin below the scales of the anterior part of the body becomes visible. This sudden exposure of blue speckles is so striking, that persons may believe that they spotted a ‘blue snake’ (‘but it was no more blue after the dog killed it). The tongue of this snake is scarlet.

040    It is non-venomous, but will strike and bite when provoked, as you can see in this picture. The black lateral stripe is conspicuous.

041    Details of the blue skin at the edges of the dorsal scales and of the skin between the scales. Actually, this is the skin of a close relative…..

042 … the mountain bronzeback (Dendrelaphis subocularis). The English name of this snake is a misnomer as it is common in lowlands and never occurs at high elevations, in contrast to some other bronzebacks. To tell it apart from the common bronzeback you need to inspect it closely.

043    The head is not copper, but dark brown. The back is more chocolate brown than bronze and many scales have black edges. It has a brownish-cream lateral line, not a sharp black one. And below the eye is one large and characteristic ‘sub-ocular’ scale.

044    This is a picture of a relatively rare bronzeback which is a true mountain snake in the north, usually living at elevations of over 1000 meter: the beautiful Cohn’s bronzeback (Dendrelaphis striatus). Thus far I only came across it in Tak province. In most sources it is not mentioned to occur in this region at all—it is believed to be restricted to the south, which is evidence that the herpetofauna of the north has not yet been explored intensively.

045    This greyish-brown snake resembles the bronzebacks: it is the Malayan ring neck (Liopeltis tricolor), a little snake with a very long tail. According the Photographic Guide it is unknown in Thailand. In fact, it occurs widely in the north. This specimen flicking its red tongue was spotted in Huai Nam Dang National Park, but it occurs also on Doi Suthep, Doi Chiang Dao and Doi Suthep, and in the mountains of Tak, Nan and Loei province.

046    Let us return to the common snakes in Chiang Mai Valley. This striped keelback (Amphiesma stolatum) is spotted frequently in gardens and orchards, right in the heart of the city.

047    This picture better shows the dark brown body with a pair of buff lateral stripes running from head to tail. The head is dark grey but may be greenish bronze, as in this specimen…

048… while the throat is yellow. It was spotted in a longan orchard in Li district, Lamphun. It is a harmless snake with a shy and gentle disposition.

049    Details of the back show why this snake is called a keelback: a pronounced keel is running through the length of the scales.

050    A number of well known water snakes are ‘keelbacks’, and the most abundant species is the chequered keelback, a good swimmer, as it shown in this picture taken by Etienne Daniels of Click and Travel, who spotted it in Huai Tung Tao. The chequered pattern is evident. Actually, the taxonomic status of this very variable snake is far from clear.

051    It is now believed that it consists of two species in the north. A more colourful one, often with red dots, ventral scales with black edges, two conspicuous streaks behind the eye and a yellow throat, is supposed to be the species Xenochrophis flavipunctatus. Specimens with a dull pattern and colouration and no black edges on the ventral scales are thought to belong to the slightly larger species Xenochrophis piscator.

Thus, the colourful specimen in this picture, taken near flooded paddies in Chiang Dao, is without doubt X. flavipunctatus.

052    Also this specimen from Sukhothai with a bright yellow throat (locally known as ngu hua luang) can only be Xenochrophis flavipunctatus.

053    On the other hand, this large (125 cm) specimen from Chiang Mai town should be Xenochrophis piscator. Thus far, I find splitting up the chequered keelback in two species little conclusive, and often come across specimens that morphologically are neither convincingly X. flavipunctatus, nor X. piscator.

Whatever species the chequered keelback belongs to, it is a quite aggressive snake compared to the gentle disposition of the striped keelback. During a defensive strike it may even jump forwards. But it will do this only when cornered, first of all it tries to flee. On smooth asphalt it often flees with side-winding (making little loops), which is the common mode of locomotion of snakes living in deserts and on mud plains.

054    Another common, ill-tempered little water snake is the yellow-bellied water snake (Enhydris plumbea), which is mildly venomous. It is predominantly nocturnal, and hides in the root tangles in ditches, flooded paddies and ponds, from where it ambushes frogs and fish. Therefore, it is rarely seen.

055    It is even better adapted to life in water than the chequered keelback. The eyes are on top of the head and the nostrils have valves. This specimen is from Sukhothai. As it looks like a large leech, Thai call it ngu pling (pling = leech).

056    Also nocturnal is the sunbeam snake (Xenopeltis unicolor), and at night you may spot it crawling in your garden, at a remarkably slow pace. As noted before, it has a gentle disposition and it needs a true provocation to make it bite. It is a very common snake, semi-fossorial, the shovel-like head facilitating digging in loose soil. In no other snakes are the scales more iridescent than in this species. It may reach a length of 100 cm.

057    Some ten kinds of kukri species occur in Thailand and there is not much consensus about the taxonomic status of them. Some are quite rare, others very variable. The most common kukri snake is probably also the most variable species known here: the banded kukri snake (Oligodon fasciolatus). This light brown specimen with two pairs of dark brown lateral stripes and butterfly shaped crossbars is from Pang Mapha district, Mae Hong Son. In Thai the snake is called ngu pi kaeo, as it resembles the flute (pi kaeo) of the traditional Thai music ensemble.

058    This specimen from Chiang Mai town is without conspicuous stripes and crossbars and does not look like a flute. Instead, it has a reticulum composed of the dark brown and white edges of the scales.

059    It is common near human habitation, and may inflict serious wounds with its enlarged rear teeth. However, it is non-venomous. The name kukri snake is derived from the resemblance of these enlarged teeth to the ceremonial kukri knives of the Ghurka warriors from Nepal. Their function may be to slit open the leather-like skin of reptile eggs, but the banded kukri is rather opportunistic and preys on a number of different small animals as well as insects and eggs.

060    At last a kukri-variant from Wang Nua, Lampang, with only dorso-lateral stripes (no crossbars and reticulum) thus resembling the striped keelback. However, the banded kukri snake is buff with four dark brown stripes, ….

061    …whereas the striped keelback is dark brown with two buff stripes.

062    With the exception of the whip snakes and the red-tailed rat snake, the snakes thus far mentioned rarely exceed 140 cm. A number of large snakes (reaching a length of 2 m or more) are also common in Chiang Mai Valley. On roads they are usually faster than small snakes, and can be spotted only for a split second. This large snake was spotted near Wiang Pa Pao, Chiang Rai.

063    Zooming in: it is probably a ‘common rat snake’ (Ptyas mucosus) which can reach a length of over 3 m. It is browish, as the Indo-Chinese rat snake (Ptyas korros), mentioned before, but the posterior part of the body and the tail have many black crossbars.

064    This picture taken at Mae Rim Snake Farm in Mae Sa Valley shows both kinds of rat snakes. Both have big black eyes. Labials and supralabials of the common rat snake (above) are black-edged; the Indochinese rat snake is slightly lighter, with no black edges on the labials and supralabials. It also misses the dark crossbars on the posterior body and tail, instead has conspicuous black-edged scales on the tail.

065    This picture shows the crossbars on the tail of the common rat snake, which, by the way, is less common in Thailand than the Indo-Chinese rat snake. The latter is called ngu sing thammada (or ‘common sing snake’) in Thai: confusion again!

066    An Indo-Chinese rat snake from Phatthalung in the south, rather uniformly coloured, but note the black edges of the scales posteriorly.

067    Juveniles of numerous Thai snake species are different from the adults, which may complicate proper identification. This is a young Indo-Chinese rat snake with narrow, cream bands on the anterior body, which disappear in the sub-adult stage.

068    Those juvenile bands resemble collars of beads, as can be seen in this picture of a specimen jumping towards the camera.

069    Allow me to show you also a picture of a juvenile mountain racer (Oreocryptophis porphyraceus) despite being a mountain snake and absolutely absent from the lowlands around Chiang Mai. This beautiful brick red snake is not uncommon on Doi Suthep.

070    In adults the basic colour fades a bit whereas the black bands get the same basic colour, except for the edges that remain black. Herpetologist Cantor, who first described the species from Sikkim in 1839, did not realize this dimorphism and considered adult and juvenile as two different species.

071    Back to the common snakes in the valley. This is the very common copperhead racer (Coelognathus radiatus) which can reach a length of over 2 m. From behind the copper-coloured head a number of characteristic black lines radiate. Broad, partly broken black stripes run over the anterior, however, the posterior and tail are dull light brown. This is a juvenile from the South. In Thai it is called ngu thang maphrao as the pattern resembles the sheet of the stalk of the coconut palm’s leaves.  In one website it is mentioned that this snake prefers coconut plantations; this is nonsense based on incomplete knowledge of the Thai language and of the snake. You can find it anywhere: in the lowlands, but also in the mountains, especially near human habitation, often many miles from the closest coconut tree!

072    It is a rather aggressive snake, but non-venomous and its bite is harmless. Therefore it is a favourite in the shows of the snake farms in Mae Rim valley. The specimen in the picture is from Mae On district, found at a high elevation.

073    Of the pictures shown thus far, only few showed snakes with a potent venom, of which a number do not even occur in or near Chiang Mai Valley. Most snakes you may encounter here are harmless. I hope that recognizing these harmless creatures from my pictures may prevent you from panicking and doing efforts to kill them when spotting them in your garden or home. Do realize that many bites occur when chasing a snake or trying to kill it!

But beside the aforementioned Malayan pit viper and red-necked keelback, a number of other potentially dangerous snakes occur in or near Chiang Mai.

The banded krait (Bungarus fasciatus) produces a very potent neurotoxin in its venom gland. This yellow-black-banded snake can reach a length of over 2 m and hunts other snakes at night. During the day it is usually rather sluggish and shy and not inclined to bite, but at night it may be ‘aggressive’. Its bite is usually not painful and victims may therefore refrain from speeding to a hospital—later they may die from respiration failure. Fatalities due to this snake are probably seriously underreported. The body form is triangular (Thai call it ngu sam liam = ‘triangle snake’) in cross section, with a sharp vertebral ridge. The bright or pale yellow bands are about the same size as the black bands. It is often confused with another, harmless, non-venomous, nocturnal snake….

074    …..the  Laotian wolf snake (Lycodon laoensis). This is a little banded snake no longer than 50 cm. Its body is round and the black bands are thrice as wide as the lemon-yellow bands. The name wolf snake suggests a ferocious animal, which it is not. The name refers to the dentition; teeth like the wolf’s.

075    This is a Malayan or blue krait (Bungarus candidus), producing a very potent venom, and potentially as dangerous as its larger cousin, the banded krait. The black bands are larger than the white ones. It has much enlarged vertebral scales. This snake is said to enter houses and bite sleeping persons. I believe that this occasionally occurs (this phenomenon is better documented in India with regard to a related krait). Joe Slowinski, a renowned expert on Asian venomous snakes, was bitten by a related species in Myanmar; it was only 30 cm long, the herpetologist died in two days. So it is not just the amount of injected venom that dictates the outcome of a snake bite.

076    The blue krait can be confused with a number of harmless black-and-white banded snakes of which the Malayan banded wolf snake (Lycodon subcinctus) is common around Chiang Mai (another similar wolf snake is a mountain snake). Thai call this snake ngu plong chanuan ban (‘banded house snake’). Juveniles are truly black-and-white banded over their entire body and tail. In adults, as the specimen in the picture, the white bands disappear except for the four or five most anterior ones. It is harmless.

077    Beside the snakes with strong venoms, large pythons (over 3 m) are potentially dangerous. Two species of pythons occur in the north, of which the reticulated python (Python reticularis) with orange blotches and white spots within a dark brown reticulum is more common. This specimen is from Phitsanulok province.

078    Following days of heavy rains and flooding, this reticulated python has taken refuge in the top of a power pole near my house in Chiang Mai.

079    Although the snake was just 250 cm long, rescue workers had problems catching it. These snakes are rather aggressive and can inflict serious wounds with their sharp teeth. Large snakes may occasionally strangle humans. Domestic fowl often attracts them.

080    In rare cases, they prey upon children, in extremely rare cases upon adult humans. In the late 1990s, a worker in a Malaysian rubber plantation was strangled by a seven-metre long python that subsequently started swallowing the man head first.  

◙081    Yet, of all snakes, the cobra is the one feared most by Thai. Three cobra species occur in Thailand, of which the Indochinese spitting cobra (Naja siamensis) is the one prevailing in the Upper North, growing no larger than 1.5 m. The colour and pattern of this snake is very variable: light-brown, buff, bronze, with or without a spectacle-, U-, V- or monocle-shaped hood mark. The body is usually uniformly coloured, but there can also be thin crossbars. I spotted this dark specimen with a vague, incomplete monocle and a wide crossbar behind the hood along the Moei River in Tha Song Yang district of Tak.

◙082    This picture of a light-coloured individual without any markings on the back of the hood was also taken in the same area. Cobras are common locally and are often associated with human habitation. Their venom is very potent and contains both neurotoxins and haematoxin. According to information released by the Queen Saovabha Memorial Institute at Bangkok’s Snake Farm, it is responsible for most fatalities due to snake bites. Many bites occur in or near paddies.

The cobra’s (and king cobra’s) phallic appearance during its defensive posture has contributed to the snake’s ill fame. Annually, cobras cause thousands of snake bite fatalities. In ancient India tolls were probably similar, giving rise to cobra worship and the creation of the mythological naga.

◙083    This is a sub-adult king cobra (Ophiophagus hannah). Adults can attain a length of over 4 m (maximum recorded: 5.80 m) and is by far the largest venomous snake in the world. Like in the cobra, colour and patterns are variable. Beside its size, it differs from the cobra by its narrower hood without markings, and the large head scales with black edges.

◙084    This picture shows the head and neck of a large king cobra at Bangkok’s Snake Farm. Victims of the king cobra are few. When it bites, a large amount of venom can be injected. Victims may succumb relatively fast; deaths within half an hour following the bite have been recorded.

◙085    The king cobra is not uncommon in the North. In May and June, baby king cobras, black with characteristic narrow, cream crossbars, are frequently found as roadkills, when after hatching they have succeeded to escape from their father, who will often loiter near the nest to eat his offspring. This is one of three such roadkills I found within a distance of one hundred metres on the road from Phrao to Chiang Dao.

◙086    People may be bitten by a cobra when the snake is accidentally cornered. Cobras, however, first of all try to flee (as most snakes will, including the king cobra). When surprised, it will raise its body. The resulting defensive posture is an effective way to scare off potential predators. It is a warning sign. This warning may be reinforced by hissing (The cobra’s Thai name, ngu hao, means ‘hissing snake’). The may even spit venom to scare off an intruder or predator. It will only strike when these repellants do not work.

The phallic hood of the cobra is just one of the many ways a snake may react to a threat. A number of other snakes have a similar defensive display. The snake in this picture, taken in Huai Nam Dang National Park, is the harmless Assamese mountain snake (Plagiopholis nuchalis), mentioned earlier. It is often believed that it is mimicking the cobra. I think both cobra and this snake have independently evolved a similar defensive display.

◙087    This common mountain snake has been renamed common blotched-necked snake in a recent work. The new name is more appropriate than ‘Assamese mountain snake’, but arrowhead snake (as the Thai name: ngu hua son) might even be a better name, as almost all specimens have a characteristic arrowhead-shaped  marking in the neck, such as the earthworm-catching individual in the picture.

◙088    Interestingly, once a blotched-necked snake tried to scare me with an alternative display, the neck flattened and the snout touching the ground. Doing so, the expanded arrowhead is upside-down and resembles the spectacles of some cobras.

You have now seen pictures of most of the snake species occurring in Chiang Mai Valley and the adjacent hills. Time was limited; therefore a few more snakes occasionally seen in Chiang Mau Valley were not mentioned: two kinds of slug snakes, two species of cat snakes, the small-spotted coral snake, the wolf snake Lycodon capucinus, and one more species of kukri snake, Oligodon taeniatus.

◙089    At last, once again, I show you the picture of the snake I showed you earlier in a split-second. You can see, it is neither cobra nor king cobra; it is also not the blotched-necked snake. It is another snake which is able to raise a hood: the big-eyed keelback (Pseudoxenodon macrops). You will certainly not encounter it in your garden, unless you live at high elevations in the mountains. I came across this specimen on Doi Suthep, somewhere in between the temple and the king’s palace. When I made pictures of it, early in the evening, Thai youngsters on their motorbikes, returning from an outing to the view point or Ban Pui village, all exclaimed in horror: ‘Ngu chong ang!’ (King cobra) or ‘Ngu hao!’ (Cobra). One cannot blame them (and you) for misidentifying this relatively rare snake.

Yet, despite the numerous pitfalls that may be encountered in identifying snakes, I believe that promoting more knowledge about the most common snakes among the populace is desirable. People may refrain from panicking when recognizing a harmless specimen, and refrain from killing it. They may be more alert and careful when they recognize a potentially dangerous species. And, maybe some will even enjoy the beauty of these fascinating animals.

Sjon Hauser: email - shauser@loxinfo.co.th