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

Ahaetulla nasuta, the Long-nosed Whip (Vine) Snake, 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.

Boiga multomaculata, the Many-spotted Cat Snake. 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. 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. Am adult from Chiang Mai Province (picture: Jacob Ohlin—with thanks!)

Calamaria lumbricoidea, the Variable Reed Snake
Calamaria pavimentata
Chrysopelea ornata, the Golden Tree Snake. 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.