Colubridae-1-A-C-Check list snakes northern Thailand


Ahaetulla nasuta, the Long-nosed Whip (Vine) Snake (pictures above). This is a very slender grass green snake measuring up to 150 cm. Head elongated with long, grooved pointed snout which is extended with a little appendage of the rostrum. Belly paler green than the upper side with a pair of narrow pale green or whitish ventrolateral stripes. Golden eye with black horizontal slit-pupil. Locally common in lowlands with agricultural fields. A. An adult specimen in captivity at the Snake Farm in Bangkok. B. Details of the head of a specimen from Lampang’s Ngao District. C. Adult hidden in a tangle of stalks and vines, Nong Phai District District, Phetchabun.
Ahaetulla prasina, the Oriental Whip Snake. Very slender snake with pointed snout, that can reach a length of 2 m. Eye with horizontal slit-pupil. Color variable: grey, blueish-green, silver-grey, but in most of northern Thailand mostly bright “grass” green. When aroused the anterior part of the body is expanded showing black and white little bars on the edges of the scalen and the interstitial skin.
A. Pale blue-green adult from Chiang Klang District, Nan. B. Bright green specimen from Wiang Kaen District, Chiang Rai. C. Pale orange-brown juvenile from Mueang Pan District, Lampang. D. Bright green adult, resting at night in vegetation, showing its slender, long body. Phu Chi Fa, Wiang Kaen District, Chiang Rai.
Boiga cyanea, the Green Cat Snake (pictures above). This Cat Snake can reach a length of nearly 2 m. It is slender and laterally compressed A), the neck is very narrow, contrasting markedly with the ovoid shaped head (C-D). The round eyes are large and have a vertically elliptic pupil (B). The upper side of the body is green, the belly white anteriorly, grayish posteriorly. In juveniles the upper side is brown, only the upperside of the head is green; the throat is yellow. It is widespread in northern Thailand, but not very common. I only came across it in evergreen forests at elevations of 800 m and higher. A. A subadult spotted on a beach in southern Thailand (thanks to the Dutch woman who sent me a video of this specimen !!). B-D. An adult in lowland forest in Pak Chong District, Nakhon Ratchasima (Northeast Thailand).
Boiga multomaculata, the Many-spotted Cat Snake (pictures above). A very slender snake with the head very distinct from the body. It can reach a length of 120 cm. The skin is covered with brown blotches. It is common throughout northern Thailand. It prefers deciduous forest but is also found in cultivated areas. A. An adult individual from Bo Kluea District, Nan. B. Subadult from Mae Taeng District, Chiang Mai. C-D. A subadult from Watthana Nikhom District, Sa Kaeo. E. An adult specimen from Hang Dong District, Chiang Mai (Thanks to Eric of Dokmai Garden for this picture!)
Boiga siamensis, the Grey or Siamese Cat-eyed Snake (pictures above). This slender, grayish-brown snake can reach a length of 170 cm. It has an intriguing pattern of brown crossbars and blotches and a row of white ocelli on the flanks at the end of the ventral shields. Widespread and common in forested hills at elevations of 150-700 m a.s.l. A. An adult from Sukhothai Province. B. A juvenile from Nakhon Thai District, Phitsanulok. C. An adult from Chiang Mai Province (picture: Jacob Ohlin—with thanks!)

Calamaria lumbricoidea, the Variable Reed Snake (above). This little, purplish-black snake (max. 50 cm) is rarely seen due to its fossorial habits. Dorsal scales are smooth shiny and shiny. The head is hardly distinct from the neck, the tail is short. The upper side shows no patterning except for a very vague pale collar in some specimens. The belly and underside of the tail is bright orange in specimens from Doi Inthanon and Doi Suthep (Chiang Mai Province) and Wiang Pa Pao District (Chiang Rai Province), but bright or pale yellow in specimens from Tak Province (Umphang, Phop Phra and Sam Ngao districts).  In the latter there is a black stripe with some reticulations on the underside of the tail. It is probably more widespread in evergreen forest above 1000 m. It’s not unlikely that the orange-bellied and yellow-bellied specimens represent different species. A-D. from Doi Inthanon, Mae Wang District, Chiang Mai. E. Adult from Umphang District, Tak. F-G. Juvenile from Umphang District, Tak.

Calamaria pavimentata. This rather rare, little reed snake will reach a length of about 30 cm. Its body is grayish-brown, not shiny such as C. lumbricoidea, and on the tail (posterior end) are 2 or 3 pink crossbars (A-B). The head is black and behind the head there may be a pale, narrow collar (A). The ground color of the belly is pale yellow or pale greenish, the ventral shield with many black grains (C). A. Specimen from Pang Mapha District, Mae Hong Son. B. A specimen from Chiang Mai’s Mae Taeng District. C. Belly of specimen from Samoeng District, Chiang Mai.

Chrysopelea ornata, the Golden Tree Snake (pictures above). This agile, green snake can reach a length of 140 cm. It is common throughout the region and is often found near human habitation and even inside houses.
A. A ‘reddish morph’, in northern Thailand only known from Mae Hong Son Province (this one from Mueang District). B. Head of an adult specimen from Mueang, Chiang Mai. C. An individual strangling a frog, Doi Saket District, Chiang Mai (thanks to Olivier for this picture). D. A specimen from Mueang District, Chiang Mai. E. An individual found inside a house in Mueang District, Chiang Mai (thanks to Etienne Daniëls for this picture!)

Coelognathus flavolineatus,  the Yellow-striped Racer
Coelognathus radiatus, the Copperhead Racer, large snake, up to 220 cm. Very common and widespread. Picture: a subadult specimen from Umphang District, Tak.