Subsessor bocourti

Bocourt’s Water Snake Enhydris Subsessor bocourti malaysia
Bocourt’s Water Snake in Malaysia (© Tom Charlton)

English name: Bocourt’s Water Snake
Scientific name: Subsessor bocourti (formerly Enhydris bocourti)
Thai name: งูไซ (Ngu Sai)

Description: To 123cm long. Robust body with large black-bordered brown bars that narrow on the sides, alternating with yellow bands that broaden on the sides correspondingly. Brown areas sometimes have thin tan-to-orange line across the top. Head is large and blunt, reddish-brown with a cream upper lip and red eyes, sometimes shows a black eyestripe but missing the Y-shaped markings that form the facemask in similar snakes. Colors become more indistinct in older snakes. Underbelly is yellowish-white with dark bars.

Relevant scale counts: 27 midbody scale rows with smooth scales, 123-132 ventrals.

Similar Species: Jack’s Water Snake has keeled dorsal scales, 40-49 midbody scale rows, is not as robust, and has a distinct dark facemask.
Deuve’s Water Snake has keeled dorsal scales, 35-39 midbody scale rows, is not as robust, has dark ventral scales and a distinct dark facemask.
Puff-faced Water Snake has keeled dorsal scales, 33-40 midbody scale rows, is not as robust, and has a distinct dark facemask.
Jagor’s Water Snake is shorter and has simple dark blotches rather than the more extensive pattern.

Range: Southern, central, and eastern Thailand, Malaysia, Cambodia, and Vietnam.

Habitat: Found in swamps, ponds, shallow lakes, rice fields, and other stagnant waters in lowlands. Is highly aquatic and usually stays near water, but will travel over land during rainy nights. Conceals itself among logs in or near water during the day.

Place in the ecosystem: Eats fish and frogs. Is eaten by larger snakes, large fish, monitors, and wading birds.

Danger to humans: Though Bocourt’s Water Snake is a rear-fanged species its venom is not a threat to human. It is not aggressive, but if restrained its large size and sharp teeth allow it to give a nasty, painful bite.

Conservation status and threats: There are no known serious threats to its Thai populations. However, Bocourt’s Water Snake is harvested for its meat and skins in several countries. In Cambodia’s Tonle Sap Lake, extended overharvest has led to the species being rarely found and it now comprises only a small proportion of the annual snake catch. There have also been declines due to overharvest in Vietnam. Much of the hunting of snakes in both countries has been constrained, but enforcement is minimal and there are concerns that many snake populations are collapsing.

Interesting facts: The largest, most robust of the water snakes in Thailand, reaching at least 3kg. Its size may contribute to why it is now being farmed for its meat and skins, which hopefully could relieve harvesting pressure on wild populations.

Like many water snakes, Bocourt’s Water Snake releases a foul-smelling musk and feces as a defensive measure when handled.

References:
IUCN Redlist: Enhydris bocourti
How the world’s largest snake hunt hurts Southeast Asia’s biggest lake
The Last Days of the Mekong Snake Hunters
Evolution in the Mud
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
A Field Guide to the Snakes of South Vietnam