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Green vine snake
Ahaetulla nasuta
6.5216, 80.119
Field Notes
Description:
This snake is diurnal and mildly venomous. The reptile normally feeds on frogs and lizards using its binocular vision to hunt. They are slow moving, relying on camouflaging as a vine in foliage. The snake expands its body when disturbed to show a black and white scale marking. Also, they may open their mouth in threat display and point their head in the direction of the perceived threat. There is a widespread myth in parts of southern India and Sri Lanka that the species uses its pointed head to blind its human victims.
Habitat:
These snakes are inhabitants of plains, hills of Sri Lanka up to 1000m, forests & almost every where in the country except for very high hill sides. They are abundant in lightly forested habitats, frequenting trees, hedges, bushes & gardens. They’re also found in India, Nepal, Myanmar, and Thailand & near Peninsular.
Notes:
Characteristics
These snakes contain a very long snout ending with a pointed tip. They have a long, cylindrical prehensile tail. Rostral appendage is seen in grown snakes. Eyes contain horizontal pupils & a concave loreal region giving a vast visible area. Dorsal median groove is present. Clear neck is present. Light, long & slender body is present.
Colour
Dorsal body is light or dark green or olive brown mixed. It’s often a bright green colour but some times even brown. Lips & chin is white in colour. Outer margin of the ventrals contain a longitudinal yellow or white line. Ventral body is white, light green, bright green or rarely brown in colour. Black & white stripes show on the front body when excited.
Venom
They’re mildly venomous. Opisthoglyphous type poison gland is present.
Dentition
These snakes contain of Maxillary: 13 or 14, Palatine: 7 to 10, Pterygoid: 17 to 28 & Mandibular: around 20
Behavior
They are diurnal & live on trees. When disturbed they try to bite & are very sensitive for movements in the environment. It has a very nasty disposition and does not like to be handled. Its habit of darting at its adversary's face is the basis of the myth that it deliberately plucks eyes hence its earning native Singhalese, Tamil and other Indian names. It does not hesitate to strike if provoked but is very easy to handle once its head and eyes are covered up in rags rendering its jaws ineffective. Strongly dislikes captivity and often strikes the glass walls of the vivarium often injuring and disfiguring itself in the process. Unlike many other snakes the Green Vine Snake lets go once bitten often leaving teeth gouged in its enemy's flesh. The bites are made by rear fang which causes mild pain, itchiness & swelling.
Breeding
They mate in June & produce offspring 3-23 by ovoviviparous. Young ones are born between March & December, after 172 days. Young are frequently born still surrounded by a membrane. Its gestation period is assumed to be around 6 months. The brood varies from 3 to 15 with extreme cases which reach well into the 20's.
Growth
At birth they measure 200-350mm & grow up to 1000-1500mm. Females are larger than the males and the males have proportionately longer tails.
Food
They hide in ambush to catch the prey for small mammals, birds, geckoes & lizards. Fish, tadpoles, & other small snakes are also known to be including in the diet. Its superb camouflage enables it to stalk its prey with ease. (Its camouflage is so effective that it is often passed off as a 'green twig' by many herpetologists) Once the prey is in striking distance it coils itself and darts towards its prey with lightning speed. The prey is often seized by the neck and killed by suffocation caused by crushing its victim’s throat with its jaws. Its venom plays a minor role in its hunting but does appear to assist in the killing process. This snake waits until its prey is completely dead before swallowing it and is reputed to tenaciously hold on to struggling prey often for more than an hour before its prey gives up the game. Rarely does its prey escape. It also includes small snakes in its diet. Big sized prey is swallowed by the help of mandibles.
Identification
The characteristic form of this snake often divulges its identity at a distance. However in order to distinguish it from its close relative A.pulverulentus it should be noted that in Sri Lanka A.nasuta is more pale to dark green with white stripes while A.pulverulentus is more towareds brownish grey. The latter often has more Ventral and Subcaudal scales, along with numerous smaller scales on its nasal appendage.
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