Almost everyone can identify a “garter snake” in Oregon!
But here’s the problem:
There are multiple species and sub-species of garter snakes! Therefore, figuring out the identity of the SPECIFIC snake you are observing can be challenging. This is especially true since many of them have similar appearances and behaviors.
Today, you are going to learn about 4 garter snake species in Oregon!
- *Just a quick note – to be officially considered a garter snake, the species must be in the genus Thamnophis*
#1. Terrestrial Garter Snake
- Thamnophis elegans
- Adults range from 18 to 41 inches in length.
- Most adults have three yellow, light orange, or white stripes; one down their back and two down their sides.
- Coloration is widely variable. Individuals may be brownish or greenish. Some have red and black spots between the stripes, and occasionally all black individuals are found.
This garter snake can be difficult to identify in Oregon!
Even trained herpetologists have issues! Its coloration varies widely, and there are believed to be 6 subspecies, although scientists still debate this.
Terrestrial Garter Snakes occupy various habitats, including both grasslands and forests. They can even be found in mountainous areas up to 13,000 feet above sea level. As the name suggests, they’re primarily found on land. But interestingly, these garter snakes can swim well!
This species is the only garter snake in Oregon with a tendency to constrict prey! Most garter snakes grab their prey quickly and just swallow, rubbing their prey against the ground if necessary.
Terrestrial Garter Snakes aren’t aggressive or dangerous, but they do possess mildly venomous saliva! It can cause a muscle infection or even kill some muscle tissue. Most bites on humans just cause pain and some swelling.
#2. Valley Garter Snake
- Thamnophis sirtalis fitchi
- Adults range from 18 to 55 inches in length.
- Coloration is brown to black with three yellow stripes; one down the back and one down each side.
- Pronounced red bars between the yellow stripes. Yellowish chin, jaw, and belly, and a black head, which often has red sides.
- Subspecies of the Common Garter Snake.
Valley Garter Snakes are found in various habitats, including forests, wetlands, scrublands, fields, shorelines, and rocky areas. They’re also well adapted to humans and are often found in urban areas.
Look for these garter snakes in Oregon under rocks, logs, and other objects, which they use for cover and thermoregulation. During the winter, they hibernate, often communally below the frost line. They will use a variety of underground cavities, including mammal and crayfish burrows, rock crevices, ant mounds, as well as manmade spaces such as foundations and cisterns.
When disturbed, Valley Garter Snakes will try to escape into the water and are excellent swimmers. If captured, be prepared for them to release musk and feces onto your hands! They may also strike, but only if they feel extremely threatened.
The Valley Garter Snake is considered a species of low risk. They are quite common and adapt well to human-modified habitats. However, they are frequently killed on roadways and are sometimes killed out of fear.
#3. Aquatic Garter Snake
- Thamnophis atratus
- Adults range from 18 to 40 inches in length.
- Coloration varies greatly depending on location and subspecies.
- They may be pale grey with alternating rows of dark blotches on the sides, dark brown with less distinct borders, or nearly all black.
- May have a yellow stripe down the back or on the neck.
The Aquatic Garter Snake occupies various habitats in southwestern Oregon, including brushlands, woodlands, grasslands, and forests. But, as the name suggests, they are always near a water source such as a pond, marsh, stream, or lake.
These snakes prey on fish, salamanders, toads, and newts. They don’t constrict their prey but may use their body to encircle it in shallow water and then strike to prevent it from escaping.
Aquatic Garter Snakes feel the safest in the water. If they feel threatened or need to escape, they flee as quickly as possible to the nearest source of water!
There are THREE subspecies of the Aquatic Garter Snake, and they are named for the approximate location they can be found; Santa Cruz, Oregon, and the Diablo Range!
#4. Northwestern Garter Snake
- Thamnophis ordinoides
- Adults average between 12 and 24 inches in length.
- COLORATION IS HIGHLY VARIABLE. Individuals can be blackish, olive, brownish, bluish, or gray, sometimes with a reddish tint.
- Typically has three stripes, one down the back and one down each side. The color of these stripes can be red, yellow, orange, tan, white, greenish, or blue; however, on certain snakes, the stripes may be dull, narrow, or absent!
The Northwestern Garter Snake prefers damp areas in western Oregon with lots of vegetation and open sunny areas. They may be spotted near houses and are often found when moving boards, logs, or other objects that they use for cover.
This species is predominantly terrestrial. However, these garter snakes can swim, and some local individuals have been observed hunting in the water! They feed mainly on slugs and earthworms, but they also prey on snails, small amphibians, and possibly fish.
The Northwestern Garter Snake will typically flee into dense vegetation if disturbed. One study found that individuals with stripes usually move away quickly because their stripes make it difficult for predators to determine their speed. But plain or spotted individuals frequently freeze while fleeing because their excellent camouflage helps them blend in while they’re motionless.
Do you need additional help identifying garter snakes?
Try this field guide!
Which of these garter snakes have you seen in Oregon?
Leave a comment below!