Northwestern Garter Snake

Thamnophis ordinoides

Northwestern Garter Snake

Thamnophis ordinoides

Other Common Names
Locally called “red racers” in Washington, referring to northwestern garter snakes with a red vertebral stripe.

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Other Common Names

Locally called “red racers” in Washington, referring to northwestern garter snakes with a red vertebral stripe.

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Appearance

The northwestern garter snake is a small to medium-sized snake, rarely exceeding 24 inches in length as an adult. The northwestern garter snake varies greatly in coloration and pattern. The topside or dorsal color is brown, dark brown, slate gray or black. The underside of this snake is usually white or yellow near its head with increasing bluish or black pigmentation towards its tail. Typically this snake has three stripes. Most individuals have one on its back referred to as its vertebral stripe and two thin lateral stripes that run along its sides. The vertebral stripe is white, yellow, orange, red, green, turquoise, or blue. The lateral stripes are white, yellow, green, turquoise, or blue. Some varieties may have small dark spots between the vertebral stripe and the lateral stripes.

Habitat

Meadows, forest clearings, and edges of coniferous forest. Also common near bodies of water.

Diet

Mainly slugs and earthworms, but also insects, small salamanders, frogs, fish, and small mammals.

Life History

During the winter northwestern garter snakes hibernate in talus banks or deep rock crevices. After emerging from winter dens, they begin activity in March and continue through early November. They remain near overwintering sites for two or more weeks until mating is complete and weather conditions allow for dispersal to summer foraging areas.

Northwestern garter snakes typically breed in the spring and again in late September and early October. Rather than laying eggs, females are ovovivparous and give birth to live young. Depending on location, broods of 8 to 12 young are born in late summer and early fall.

Young northwestern garter snakes are independent at birth and do not require further parental care.

IUCN Status

Least Concern

Ecosystem & Cultural Importance

Northwestern garter snakes play an important role in rodent and invertebrate control. They also contribute to the food chain in their native range as a food source for a variety of predators.

Found in southern Canada and northwestern United States, including southwestern British Columbia, western Washington, western Oregon, and northwestern California.

The northwestern garter snake occurs in wooded areas on the floor of the Willamette Valley and has been found in the Rogue Valley. It is also commonly found in suburban areas and city parks.

Garter snakes defend themselves by releasing the contents of their cloaca and musk glands. They smear this pungent foul-smelling mixture over themselves and their attackers. Some will also regurgitate the contents of their stomach, and most will bite. Garter snakes are mildly venomous and even though this helps them obtain prey, it is not typically dangerous to people.

Like other garter snake species, the northwestern garter snake incapacitates their prey by constricting and swallowing them whole.

Citations & Other Resources

Hammerson, G.A. 2007. Thamnophis ordinoides. The IUCN Red List of Threatened Species 2007.
Washington Department of Fish & Wildlife. N.d. Northwestern gartersnake. https://wdfw.wa.gov/species-habitats/species/thamnophis-ordinoides#living
Oregon Department of Fish & Wildlife. N.d. Northwestern garter snake. https://myodfw.com/wildlife-viewing/species/northwestern-garter-snake
Nussbaum, R. A., E.D. Brodie, and R.M. Storm. 1983. Amphibians and reptiles of the Pacific northwest. University Press of Idaho.
Bartlett, R. D., and P. Bartlett. 2009. Guide and reference to the snakes of western North America (north of Mexico) and Hawaii. University Press of Florida.

Northwestern Garter Snake

Northwestern Garter Snake

Other Common Names

At the Aquarium

Appearance

Habitat

Diet

Life History

IUCN Status

Ecosystem & Cultural Importance

Citations & Other Resources

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