Reptiles
Northwestern Garter Snake
Thamnophis ordinoides · also called northwestern garter snakes
Two northwestern garter snakes cross paths in a damp Pacific coast forest clearing, one plain and dark, the other striped in bright orange, a colour difference striking enough to make a casual observer wonder whether they are even looking at the same species.
Overview
The northwestern garter snake, Thamnophis ordinoides, is a small, active snake native to forest and grassland habitat along the Pacific coast from British Columbia south through Washington, Oregon, and northern California. Its extraordinary colour and pattern variation, specialised slug-hunting diet, and daytime activity pattern make it one of the more visually diverse and behaviourally distinctive garter snakes in North America.
A single species wearing dozens of looks
Few North American snakes show anywhere near the colour variation found within a single northwestern garter snake population, a diversity dramatic enough that individuals can look like entirely different species side by side.
Status
Least Concern — widespread and common across suitable forest and grassland habitat throughout its Pacific coast range.
Northwestern Garter Snake: common questions
Why does the northwestern garter snake show so much colour variation?
This species shows more colour and pattern variation than almost any other North American snake, with individuals from a single population ranging from plain dark forms to bright orange, red, or blue striped patterns, a diversity that researchers believe may relate to different predator-avoidance strategies working equally well within the same population rather than one single pattern being clearly superior.
What does the northwestern garter snake eat?
This species feeds primarily on slugs, earthworms, and small amphibians, readily hunting soft-bodied prey such as slugs that many other predators find less appealing, making it an effective natural check on slug populations within the damp forest and grassland habitat it occupies.
Is the northwestern garter snake active during the day or night?
This species is primarily active during the day, hunting and basking in daylight hours, a diurnal activity pattern rather than relying on nocturnal hunting, which makes it one of the more commonly observed garter snakes for people out during daytime hours within its Pacific coast range.
Where does the northwestern garter snake live?
This species is native to forest and grassland habitat along the Pacific coast from British Columbia south through Washington, Oregon, and northern California, generally favouring damp conditions that support the slugs and earthworms making up much of its diet.