No, there are no true water snakes from Genus Nerodia native to Washington State. However, there are other species of semi-aquatic snakes in the state, like the garter snake and the western terrestrial garter snake, that exist in wetlands and other water sources around the state.
Thanks to Washington’s diverse landscape and its commitment to conservation, there are also many species of other snakes, including the western rattlesnake, rubber boa, red racer, and northern Pacific rattlesnake, that can be found in various parts of the state.
In this article, we will explore the different semi-aquatic snakes that exist in Washington, as well as their unique characteristics and habitats. We’ll also look at the difference between semi-aquatic snakes and how these creatures differ from their full-fledged water snake relatives.
What Are Water Snakes?
Water snakes are a genus of nonvenomous, semi-aquatic colubrid snakes from the family Colubridae and subfamily Natricinae. They are typically found in freshwater bodies around North America and can survive both in and out of water for extended periods of time. Water snakes vary greatly in size and coloration, with some species growing up to four feet long while others remain relatively small.
What are semi-aquatic snakes?
Semi-aquatic snakes are well adapted to both aquatic and terrestrial habitats, spending part of their time in the water and on land. They are a combination of different garter species, water snakes, and some non-venomous colubrids.
These snakes have certain adaptations that allow them to swim and hunt efficiently in the water, such as streamlined bodies. They are also able to move and hunt effectively on land.
Some examples of semi-aquatic snakes include the water snake, the cottonmouth, and the green sea turtle. These snakes play an important role in their ecosystems, serving as both predators and prey for other aquatic and terrestrial animals.
What’s the difference between semi-aquatic snakes and true water snakes?
Semi-aquatic snakes are a general category of snakes that are adapted to both aquatic and terrestrial habitats, while water snakes from the genus Nerodia are a specific group of semi-aquatic snakes.
Water snakes from the genus Nerodia are commonly known as true water snakes native to North America and are only found in slow-moving fresh-water bodies. They are strong swimmers and have adapted their bodies to allow for greater agility in the water. Their flattened tails, webbed feet, and streamlined bodies give them an edge when moving through the water.
On the other hand, semi-aquatic snakes are not limited to one genus or species. They usually come from a variety of garter species, water snakes, and some non-venomous colubrids. They have adapted to both aquatic and terrestrial habitats but may not be as well suited for movement in the water due to their lack of specific adaptations like webbed feet or a streamlined shape.
What species of semi-aquatic snakes are found in Washington?
Washington is home to only two semi-aquatic snake species: the common garter snake (Thamnophis sirtalis) and the western terrestrial garter snake (Thamnophis elegans). These snakes can be found in the state’s wetlands and other water sources, such as streams, rivers, ponds, and lakes.
Let’s look at these two species in a bit more detail:
1. The common garter snake
- Scientific name: Thamnophis sirtalis
- Length: Adults can reach up to 54.0 inches (137.2 centimeters)
- Habitat: Can be found in wetlands, ponds, lakes, rivers, creeks, and stream edges.
- Diet: Frogs, toads, fish, and other small aquatic animals
- Behavior: Nocturnal activity and hibernation during the winter months
The common garter snake is a species of semi-aquatic snake that is widely distributed throughout North America, including in Washington state. They are named for the distinctive stripes that run along their bodies, which resemble the garters traditionally worn to hold up socks.
The stripe pattern can be either green, yellow, or red, depending on the particular subspecies and their environment. The stripe pattern helps to camouflage the snake in its habitat, making it difficult for predators to spot. These snakes are characterized by their slender bodies and smooth scales that are arranged in 17 rows along the back.
There are two subspecies of common garter snakes found in Washington: the red-spotted garter snake, often found in southwestern Washington, and the Puget Sound garter snake, found in Northwestern Washington.
The common garter snake is not venomous and poses no threat to humans. It is a non-venomous species that feed on various prey, including fish, frogs, and other aquatic animals. They are often found near bodies of water where they hunt for food.
As a semi-aquatic species, the common garter snake has several adaptations that allow it to exist in both aquatic and terrestrial habitats. For example, they have a flattened tail that provides propulsion in the water, allowing them to swim and hunt efficiently.
They can also close their nostrils and eyes underwater to prevent water from entering their respiratory and ocular systems. These adaptations make this snake well-adapted to life in and around the water.
2. The western terrestrial garter snake
- Scientific name: Thamnophis elegans
- Length: Adults can reach up to 41 inches
- Habitat: Found in wet areas such as swamps, marshes, streams, creeks, wetlands, and ponds.
- Diet: Mainly eat amphibians, insects, fish, and other small animals.
- Behavior: Nocturnal activity and inactivity during the winter months
The Western Terrestrial Garter Snake is a species of North American water snake found in the western United States, ranging from northern California to British Columbia. It is one of two species of terrestrial garter snakes, the other being the Eastern terrestrial garter snake.
The Western terrestrial garter snake is a small species, with adults typically reaching around 18–41 inches in length. They have slender bodies and usually three longitudinal stripes running along the back and sides. The top stripe is typically yellow or light orange, while the side stripes are typically white or light gray.
Western terrestrial garter snakes can be found in a variety of aquatic habitats throughout Washington state, including ponds, marshes, lakes, streams, and rivers. They are most commonly found in lowland areas near waterbodies such as Puget Sound and Willapa Bay.
They are also occasionally spotted on beaches and saltwater estuaries. While they tend to stay close to water sources, they will sometimes venture far from them in search of food or shelter.
Western Terrestrial Garter Snakes are non-venomous and generally harmless. However, if threatened or provoked, they may bite or secrete a foul-smelling musk for defense purposes. Despite their harmless nature when left alone, these snakes are often killed out of fear by unknowing people who mistake them for more dangerous species like rattlesnakes or copperheads.

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