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Jagor’s Water Snake

23 Apr

Enhydris jagorii

Jagor's Water Snake Enhydris jagorii

Jagor’s Water Snake from Uttaradit Province (photo courtesy of John Murphy)

Jagor's Water Snake Enhydris jagorii

Another Jagor’s Water Snake from Uttaradit Province (photo courtesy of John Murphy)

Jagor's Water Snake Enhydris jagorii

Head shot of Jagor’s Water Snake, showing scale features (photo courtesy of John Murphy)

English name: Jagor’s Water Snake (aka: “Bangkok Mud Snake”)
Scientific name: Enhydris jagorii
Thai name: Ngu Sai-rung Lai Kwan

Description: To 68cm long. A short, thick snake. Head is short and rounded. Body is grayish-brown to dark brown with black blotches in a line down the sides. Underbelly is pale.

Similar Species: Chanard’s Mud Snake has a light yellow line and row of small dark spots on the sides rather than larger dark blotches.
Yellow-bellied Water Snake is uniformly dark above with no spots.
Puff-faced Water Snake is lighter in color with a light barred pattern on body and dark mask on the face.
Rainbow Water Snake has a smaller head and light stripes rather than dark spots.
Bocourt’s Water Snake is much larger and has narrow yellow banding on black/brown background coloration.
Tay Minh Water Snake is extremely similar in appearance to Jagor’s Water Snake, but is only found in the Mekong Delta.
Mekong Mud Snake (Enhydris subtaeniata) also is very similar in appearance, though it often has more prominent light striping above the dark spots. It is found in the Mekong Delta and the Bung Boraphet area of Nakorn Sawan province, not Bangkok.

Habitat: Found in floodplains, freshwater swamps and shallow marshes, including artificial wetlands and rice paddies.

Contribution to the ecosystem: Helps control fish and frog populations. Provides food for larger snakes, large fish, monitors, and wading birds.

Danger to humans: Is an aggressive rear-fanged species and will bite when threatened but is not dangerous to humans.

Conservation status and threats: This species may only be known from the Chao Phraya drainage, though it may have a wider distribution. It is locally abundant where it is found, but the potentially limited extent of its range is a cause for concern as human encroachment and the possible draining or pollution of its wetlands are a threat to its current habitat.

Interesting facts: References to Jagor’s Water Snake vary widely on its current distribution. Some sources state that it is only found in a single location in the Central Plain, others state that it is found broadly in the Central Plain and Southeastern Basin, including Bangkok, and still others state that it is a wide-ranging species that can be found in most of Thailand and beyond. Why the discrepancy? It’s likely due to taxonomic confusion. New species are discovered every year in Thailand, and often what was previously thought to a be a single species turns out to be 2, 3, or even 10 or more different species. At the same time, different species discovered in different areas sometimes turn out to have been the same species all along. As these things get sorted out, different references will update their records at different times (or sometimes even refuse to accept the same explanation), and thus such discrepancies arise.

In this case, the problem is likely that the Tay Minh Water Snake and Long-head Water Snake are species of water snake which are extremely similar to Jagor’s Water Snake, but are found in other areas. The Tay Minh Water Snake is found only in the Mekong Delta, while the Long-head Water Snake is only found in Tonlé Sap Lake, Cambodia. Jagor’s Water Snake was also confused with Chanard’s Mud Snake and the Mekong Mud Snake. Most of the records of Jagor’s Water Snake from outside the Chao Phraya drainage are probably the result of confusion with another species.

References:
A New Thai Enhydris
IUCN Redlist: Enhydris jagorii
IUCN Redlist: Enhydris subtaeniata
Siam-Info: Homalopsinae
Reptile Database: Enhydris jagorii
Thailand Office of Environmental Planning and Policy: A Checklist of Amphibians and Reptiles in Thailand
John C. Murphy, personal communication
Michael Cota, personal communication
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
Snakes of Thailand and their Husbandry

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