Coelognathus radiatus

copperhead rat snake racer trinket snake Coelognathus radiatus hong kong
Copperhead Rat Snake in Hong Kong (© Kevin Caldwell)

English name: Copperhead Rat Snake (aka “Radiated Rat Snake”, “Copperhead Racer”, “Copperhead Trinket Snake”)
Scientific name: Coelognathus radiatus (formerly Elaphe radiata)
Thai name: งูทางมะพร้าว (Ngu Taang Mapao)

Description: To 230 cm long. One of the larger snakes in Bangkok. Body light brown in the front, fading to a yellowish or orangish tan toward the back of the body. Two prominent black stripes run down the first half of each side of the body. Three black lines radiate back from the eye, two slanting downwards and the other running up until it hits a black collar at the back of the head.

Relevant scale counts: 19 rows of midbody scales.

Similar Species: Asian Rat Snakes (Ptyas korros and Ptyas mucosus) lack the black stripes on the front half of the body and the unique markings on the head.
Painted Bronzeback has a yellow-to-cream stripe on its body and lacks the markings on the head.
Monocled Cobra lacks the striping on the front half o the body and lacks the markings around the eye.

Range: From northeast India through Bangladesh, Myanmar and southern China into southeast Asia to Malaysia and Indonesia.

Habitat: Prefers open grassland and shrubland, but is also found in forests and agricultural habitats. Can be found in urban areas, even where there is only a small pocket of natural habitat.

Place in the ecosystem: The Copperhead Rat Snake feeds on rats and mice and helps control Bangkok’s rodent populations. It also eats birds, lizards, and frogs. Juveniles of the species provide food for larger snakes, monitors, and birds of prey.

Danger to humans: This snake is aggressive when threatened and is large enough to inflict some damage with its bite. A recent study has found that it produces some venom, quite similar to the venom of cobras. However, it only produces a small amount of venom and does not have venom-injecting fangs, so effects in humans are limited to redness and mild swelling at worst.

Conservation status and threats: In Thailand this snake is common with no known conservation issues, but it is listed as Endangered on the China Red List.

Interesting facts: The Copperhead Rat Snake is a fast snake that will first try to flee when threatened, but when cornered will lift the first third of its body off the ground, curl its neck and body into an “S” shape, expand its neck vertically and strike aggressively with its mouth open. If that fails, it will sometimes proceeds to play dead as a last resort.

University of Hong Kong: Coelognathus radiatus
Isolation of a neurotoxin (alpha-colubritoxin) from a nonvenomous colubrid
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Snakes of South Vietnam