Snakes in Mongolia

The snakes of Mongolia are poorly known; currently scientists recognize nine native snake species, representing three families: Colubridae, Erycinae and Viperidae. Three of the species are venomous, three are constrictors; the remaining three species prey on cold-blooded prey, simply swallowing their prey live.

Colubrids

Five colubrid species inhabit Mongolia. Two rat snakes represent the genus Elaphe and kill prey with constriction. Dione’s rat snake (E. dione) is a terrestrial habitat generalist who feeds on rodents, birds and their eggs. Like Dione’s rat snake, the Amur rat snake (Elaphe schrencki) exhibits habitat flexibility but is more arboreal than Dione’s rat snake. Amur rat snakes reach 5 feet in length, but Dione’s rat snakes average less than 3 feet. Frog- and fish-eating grass snakes (Natrix natrix) reach about 3 feet, and feign death as a defense mechanism. Grass snakes deposit eggs in the early summer; the young hatch in autumn and begin hunting small amphibians immediately. Two racers live in Mongolia, but they are not closely related. The slender racer (Coluber spinalis) is poorly known, though likely uses his speed to catch rodents, lizards and frogs like his New World relatives. The steppe ribbon racer (Psammophis lineolatus) is a slender species who ranges as far east as Iran. Though scientists have not studied the species in detail, the snake's large eyes are likely an adaptation for visually pursuing prey.

Sand Boas

Tartar sand boas (Eryx tataricus) live in the foothills and arid grasslands of Mongolia. The largest of the sand boas, these 4-foot-long snakes are powerfully built, capable predators of rodents, lizards and birds.Sand boas engage in ovoviviparous reproduction; babies remain in unshelled eggs, which are held inside their mother, throughout the incubation process. They hatch from the soft eggs at or near the time of their birth.

Vipers

The adder (Vipera berus) is the only true viper living in Mongolia. The adder has one of the largest ranges of any venomous snake in the world, and ranges from West Europe to the Pacific coast. Because of the region’s cold climate, these snakes prefer open habitats with abundant basking opportunities. Adders sometimes hide in dense clusters of vegetation, ambushing small rodents, lizards and frogs that pass by. Alternatively, adders will actively pursue prey, primarily at dusk. Adders are small snakes, rarely exceeding 3 feet in length and 4 ounces in weight. The venom of adders is rarely life threatening, but very painful.

Pit Vipers

Two pit viper species occur in Mongolia: Asian pit vipers (Gloydius halys) and Amur pit vipers (Gloydius intermedius). Both species have thermoreceptive pits located on the front of their faces, which allow the snakes to see warm-blooded predators or prey, even in the dark. Both species reach a maximum length of about 3 feet. The Asian pit viper’s venom is milder than many other pit vipers; a few people have died from the bite, but this is rare. Little is known about the Amur pit viper’s venom and no species-particular antivenin is available. Both species prefer to live in open forests and rocky areas, where they prey primarily on rodents.