Western Terrestrial Garter Snake

Facts, Identification & Control

Latin Name

Thamnophis elegans

Appearance

Most western terrestrial garter snakes have a yellow, light orange or white stripe on their back, accompanied by two stripes of the same color, one on each side. Some varieties have red or black spots between the top and side stripes. The snake’s underside is a dark olive-brown or black with a few markings. It is an immensely variable species, and even the most experienced snake experts have trouble identifying the several subspecies of this snake. They are medium-sized, usually 18 – 41 inches, with a head barely wider than the neck. Western terrestrial garter snakes are sometimes mistaken for bull snakes or rattlesnakes.

Behavior, Diet & Habits

Unlike other species of garter snakes, the western terrestrial garter snake has a well-documented tendency to constrict prey, although the constriction is inefficient when compared with the constriction of many other snakes. Snakes from Colorado populations appear to be more efficient at killing their prey by constriction than those from Pacific coast populations. Western terrestrial garter snakes generally breed in the spring, but fall mating has been reported. Like all garter snakes, they give live birth rather than laying eggs. Usually 4-19 young are born between July and September.

This snake eats a wide range of prey, including frogs, tadpoles, fish, birds, mice, lizards, other snakes, worms, leeches, slugs, grasshoppers, small land mammals and snails. T. elegans is one of only two garter snakes known to cannibalize its own.

The western terrestrial garter snake is found across the western half of North America. It occurs in a wide variety of habitats, from sea level to high mountains, in grasslands, scrublands, woodlands, rocky hillsides, and open areas in forests. It is chiefly terrestrial in most areas, but can also be aquatic at higher elevations. In general, it is more commonly observed at lower elevations around water.

More Information

While garter snake bites are generally innocuous to humans, it is best not to handle the western terrestrial garter snake or its close cousin the wandering garter snake. Oftentimes, when these snakes are handled, they will thrash about, spiraling over and over in an attempt to escape. However, its best escape tactic is the release of a smelly mix of musk and feces. In addition, western terrestrial and wandering garter snakes will readily bite if feeling extremely threatened. The venom of the wandering garter snake is regarded as the most toxic of all garter snake species.

When snakes are a problem, the best course of action is to call a pest management professional (PMP) who has the tools and knowledge to address snake problems.

Snake encounters can be discouraged by eliminating or reducing their food supply and cover. Since vegetation and debris are major snake attracters, mow closely around homes and outbuildings, store firewood and lumber away from residences and reduce piles of rocks, leaves or other items that give snakes shelter. Seal cracks and crevices in buildings and around pipes and utility connections. Small areas where children might play can be protected from most snakes with a snake-proof fence. Use of ultrasonic sound emitters (snakes can’t hear, at least in high frequencies) or fake owls or hawk decoys do not work to repel western or wandering garter snakes.