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Are There Water Snakes in Oregon?

No, there are no water snakes in the state of Oregon. While there are many different species of snakes in the Pacific Northwest, none of them are classified as true water snakes. However, there are several species of semi-aquatic snakes that can be found in the region. It is important to note that there is a very big difference between water and semi-aquatic snakes.

In this article, we will explain what makes a snake a true water snake, which species of semi-aquatic snakes can be found in Oregon, and why it is important to understand the difference between the two. So read on to find out more.

True water snakes

All true water snakes are members of the genus Nerodia, which includes nine species, all native to North America. These snakes are found near water sources and spend the majority of their time in and around wetlands.

Members of the genus Nerodia include the N. paucimaculata, N. transverse, N. cyclopion, N. erythrogaster, N. harteri, N. rhombifer, N. sipedon, N. fasciata, N. taxispilota, and N. clarkii. Although none of these water snakes are native to Oregon, they can be found in other regions of North America.

All water snakes are non-venomous and feed mainly on fish, frogs, and other small aquatic organisms. They are all heavy-bodied and can grow up to 4 feet long. It is also important to note that water snakes do not lay eggs like other species of snakes; they give birth to live young.

Semi-aquatic snakes

Semi-aquatic snakes are species that spend the majority of their time on land but can also be found near or in water. These snakes typically live in moist environments such as marshes, swamps, and lakes.

Two species of semi-aquatic snakes are found in Oregon: the Pacific coast aquatic garter snake and the Western terrestrial garter snake. These species are not exactly water snakes, but they can be found in and around aquatic environments.

1. Western terrestrial garter snake

western terrestrial garter snake
Western terrestrial garter snake | image by Paul Asman and Jill Lenoble via Flickr | CC BY 2.0
  • Scientific Name: Thamnophis elegans
  • Length: 18-43 inches
  • Range: Found in most of Oregon; however, they are absent from the north and central coast region, the east slope and crest of Cascade Mountains, and a small portion of central Oregon.

The Western Terrestrial Garter Snake can be identified by its gray-brown or black coloration and dark checkered pattern between yellow stripes. There are three subspecies recognized in the state. They include the Coast Garter Snake (T. e. terrrestris), which is found in the southwest corner of Oregon.

Then there is the Mountain Garter Snake, which can be found throughout the Willamette Valley and southwest Oregon, and the Wandering Garter Snake (T. e. vagrans), located east of the Cascade Mountains. They feed on small fishes, frogs, salamanders, tadpoles, and earthworms.

Western terrestrial garter snakes inhabit moist and wet areas near slow-moving water bodies such as streams and ponds, and they feed on small fishes, frogs, salamanders, tadpoles, and earthworms. They are active during the day and seek shelter in small crevices or holes to avoid predators.

In the winter months, they hibernate. By seeking shelter and hibernating, the garter snakes can protect themselves from predators and survive until warmer weather arrives.

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Breeding takes place in the spring, after hibernation and when temperatures rise. Mating occurs once a year, with females giving birth to an average of 12 live young after a gestation period of 2-3 months. Both males and females reach sexual maturity at the age of two.

2. The Pacific coast aquatic garter snake

  • Scientific Name: Thamnophis atratus atratus
  • Range: Found along rivers in southwestern Oregon, as far north as the Umpqua Valley in Douglas County.

The Pacific coast aquatic garter snake is a non-venomous species of snake. It can be easily identified by its distinctive pattern featuring an olive brown to gray background, with three longitudinal yellow stripes running down its body.

Depending on the individual snake, these stripes may have a checkered or barred-like style and can be somewhat brighter or duller. This patterning helps blend it in with its surrounding and makes it more difficult for predators to spot. Adult snakes can grow to be 18 to 33 inches long.

The Pacific coast aquatic garter snake feeds on small fish, fish eggs, salamanders, tadpoles, frogs, toads, earthworms, and leeches in its natural habitat. They prefer wet meadows, riparian areas, marshes, and moist forests near rivers, streams, lakes, and ponds.

It is an excellent swimmer and will dive into the water to evade predators or seek refuge. They are most active during the day and can be found basking in the sun on rocks, logs, and vegetation near bodies of water.

Commonly asked questions about the snakes found in Oregon

1. Are these Oregon snakes venomous?

No, neither the Pacific coast aquatic garter snake nor the Western terrestrial garter snake is venomous to humans. Despite this, the latter is equipped with mild venom, which it uses to subdue its prey.

This venom can cause irritation if you come into contact with it. As such, it is best to treat these snakes with caution, as they may bite if provoked.

2. Do these aquatic snakes lay eggs or give live birth?

No, aquatic and semi-aquatic snakes do not lay eggs. Instead, they give birth to live young. This process is known as ovoviviparity, which is a type of reproductive strategy whereby the mothers retain the fertilized eggs inside their bodies until they are ready to hatch.

The mother then gives birth to fully formed juvenile snakes. This is different from other species of snakes that lay eggs and incubate them until they hatch.

3. How long do Western terrestrial garter snakes live?

On average, Western terrestrial garter snakes can live up to 7 years in the wild. However, they are known to live up to 15 years when kept in captivity.

This is because they are provided with a more consistent supply of food and shelter, which helps them avoid predation and other environmental threats.

4. Are any of these “water” snakes aggressive?

Yes, even though they are not venomous, both the Pacific coast aquatic garter snake and Western terrestrial garter snake can become aggressive if they are startled or disturbed.

And given that their mouths are lined with tiny, sharp teeth, their bites can be painful. As a result, it is best to observe these snakes from a distance and not attempt to handle them or provoke them in any way.

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5. What should you do if you encounter a water snake in Oregon?

If you encounter a semi-aquatic snake in Oregon, the best thing to do is observe it from a distance and give it plenty of space. Do not attempt to touch or capture the snake. Contact your local wildlife center or the Oregon Department of Fish and Wildlife for assistance if the snake appears injured or distressed.