Oregon is located in the Pacific Northwest region of the United States. The climate along the coast is cool and humid, transitioning to semi-oceanic with hot, dry summers in the Willamette Valley. Further inland, there is an arid continental climate, while in the mountain ranges such as the Cascade Range, there may be heavy winter snowfalls.
A wide variety of habitats can be found throughout Oregon, including forests, grasslands, wetlands, and coastal areas. The state does not actually have any true water snakes, however, there are two species of snake that are semi-aquatic: the Oregon garter snake and the mountain garter snake.
Oregon Water Snakes
1) Oregon garter snake (Thamnophis atratus hydrophilus)
- Native to the Pacific Coast
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
Oregon garter snakes grow to lengths of 46 – 102 cm (1 ft 6 in – 3 ft 4 in) and have a slender build with a narrow head. These snakes are usually dark gray, brown, or black in color, with a broad, yellow dorsal stripe running from the back of the head to the tip of the tail. The sides are also yellow in coloration, although they may also be peppered with dark spots. In some individuals, these stripes may be almost completely obscured.
The best place to see this species in Oregon is along the coast in Douglas County, where it occupies creeks, streams, small lakes, and ponds surrounded by woodland or brush. Adults forage in a wide variety of habitats, feeding on juvenile salamanders, fish, and tadpoles. Amphibians are of particular importance in the diet of garter snakes, and declines in their populations could potentially have detrimental effects on Thamnophis atratus hydrophilus.
Garter snakes are resistant to tetrodotoxin, a neurotoxin produced by some newts. As well as this protective mechanism against prey defenses, garter snakes have antipredator strategies. These include curling into a tight coil or becoming aggressive toward their attacker.
2) Mountain garter snake (Thamnophis elegans elegans)
- Native to North America
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The mountain garter snake grows to lengths of 46 – 104 cm (1 ft 6 in – 3 ft 5 in) and has very variable coloration – this can make it quite tricky to identify! Its background coloration varies between brown, olive green, and gray, and most individuals have a yellow, orange, or white dorsal stripe, with a matching stripe down each side. There may also be black or red spots in between these stripes.
Thamnophis elegans elegans is a subspecies of the western terrestrial garter snake – which, despite its name, is often associated with water, residing in streams, ponds, and damp meadows. In Oregon, this subspecies can be found in the southwest of the state, the Klamath-Siskiyou Mountains, and the Cascade Mountains. Individuals feed on mice, leeches, frogs, and fish.
Somewhat unusual for members of Squamata, the mountain garter snake gives birth to live young, typically producing around thirty at once. The young are precocial and are immediately independent, left to fend for themselves and source their own food. Populations of this species are stable, and there are no imminent threats.
