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Are There Water Snakes in Montana? 

Montana is a state full of wide open skies, burbling mountain streams, and rocky pine forests. In addition to its great scenery, it supports a bevy of diverse wildlife species. Reptiles like snakes are one such type of animal native to Montana. Learn more about the water snakes in this western state by reading more.

Are There Water Snakes in Montana?

There are no water snakes of the genus Nerodia in Montana. Most water snakes live in the eastern United States. Montana has harsh winters and less water than eastern states, which makes it harder for water snakes to survive. There are 10 species of snakes in the state including a few species of semi-aquatic snakes.

Semi-Aquatic Snakes in Montana

Even though there are no actual water snakes in Montana, the state is still home to some snakes that rely on water for hunting and habitat. These snakes live nearby bodies of water and even spend time in water.

We’ll start with a few species of garter snakes. These snakes aren’t always found in water, but the Genus Thamnophis (garter snakes) is closely related to the Genus Nerodia (water snakes) as they are both in the same sub-family of Natricinae.

1. Common Garter Snake

Common garter snake
Common garter snake | image by Greg Schechter via Wikimedia Commons | CC BY 2.0
  • Scientific name: Thamnophis sirtalis
  • Length: 23” to 30”
  • Venomous: Yes (mild)

The Common Garter Snakes are adaptable snakes that adjust to living on land and in water. They are dark in color with light yellow or white stripes running the length of their bodies.

This snake doesn’t pose much of a threat to people. In fact, many reptile enthusiasts keep Common Garter Snakes as pets. These snakes are venomous, but it is not enough to kill a person. Bites are painful and cause irritation.

In the wild, they eat invertebrates, small mammals, and aquatic crustaceans and fish. Look for them throughout the state of Montana. You’re more likely to spot them in the spring and summer when temperatures are warm.

2. Plains Garter Snake

Plains garter snake
Plains garter snake | image by Peter Paplanus via Flickr | CC BY 2.0
  • Scientific name: Thamnophis radix
  • Length: 16” to 28”
  • Venomous: No

The Plains Garter Snake resembles its cousin the Common Garter Snake in coloring. Both have a dark base color and light yellow or white stripes from their head to tails. The Plains Garter Snake has a few differences, however.

It is specialized to life in the grasslands and open landscapes of the northern prairies. It lives only in eastern and northern Montana. It’s smaller than the Common Garter Snake as well.

The Plains Garter Snake adapts well to human infrastructure and water sources of varying quality. They live near ponds, streams, and lakes, where they eat small rodents and aquatic invertebrates.

3. 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” to 41”
  • Venomous: No

The Western Terrestrial Garter Snake is a brilliantly colored garter snake. It has a bright orange body with dark brown patches and a white stripe that runs from the head to the end of its tail. Its head is dark brown and its belly is yellow or white.

This snake lives throughout Montana at elevations as high as 13,000 feet. They rely heavily on water sources like ponds and streams to find frogs, fish, and invertebrates to eat. Snakes in the Rocky Mountains are more likely to live in water than snakes in the plains.

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Look for the Western Terrestrial Garter Snake in Western, Central, and Southeastern Montana.

Other Snakes in Montana

The other species of snakes in Montana aren’t very reliant on bodies of water to live. Many get the hydration they need from their prey.

4. Prairie Rattlesnake

source: White Sands National Park
  • Scientific name: Crotalus viridis
  • Length: 24” to 45”
  • Venomous: Yes

The Prairie Rattlesnake is the only venomous snake in Montana. It might look solid-colored at first glance, but it actually has dark splotches along its back and sides. Recognize them based on their rattle and their triangle-shaped head.

Rabbits, rats, and prairie dogs are this snake’s main food sources. They inhabit the entire state, in areas lower than 6,400 feet elevation.

If you encounter a Prairie Rattlesnake, put distance between yourself and the snake as soon as you can. Unless the snake is cornered, it is unlikely that it will attack.

5. Northern Rubber Boa

Rubber boa
Rubber boa | image by andrewnydam via Wikimedia Commons | CC BY-SA 4.0
  • Scientific name: Charina bottae
  • Length: 14” to 28”
  • Venomous: No

Northern Rubber Boas are stocky, well-built snakes that live in the mountains and forests of Montana. They prefer enclosed and shady areas where they can blend in with the forest floor. Some populations live in elevations as high up as 7,000 feet.

This snake’s back and sides are dark brown or olive-colored. Females are a tad bigger than males, but both are effective hunters. Shrews, which they hunt for at night, make up most of their diet. The Northern Rubber Boa lives in the western part of Montana.

6. Plains Hog-nosed Snake

Plains hognosed snake
Plains hognosed snake | image by Peter Paplanus via Flickr | CC BY 2.0
  • Scientific name: Heterodon nasicus 
  • Length: 15” to 25”
  • Venomous: No

The Plains Hog-nosed Snake is a specialist in its grassland environment. The first thing you’ll notice about this snake is its upturned nose. It uses its head like a shovel to brush up soil and mud near water sources.

These usually disturb toads and salamanders, the Plains Hog-nosed Snake’s favorite prey. Their scales are an intricate design of tan, white, and brown. On top of a tan base color are blotches of brown with white rings.

They are talented actors, too. When threatened, they rattle their tails and hiss to convince their attacker they are a rattlesnake. If the threat doesn’t take the hint and leave, they lay on their backs and play dead.

To up the gross factor, they vomit and defecate. It lives below 4,000 feet in the plains of central and eastern Montana.


Are there venomous water snakes in Montana?

There are no venomous water snakes native to Montana. The true water snakes, members of the genus Nerodia, are not venomous anyway.

The state’s only venomous snake, the Prairie Rattlesnake, rarely ventures into aquatic environments. It prefers to live in open grasslands and prairies where water is scarcer.

How many species of snakes live in Montana?

Montana is home to 10 species of snake. None of the 10 snakes are true water snakes.

Three of the 10 snakes can be classified as semi-aquatic. Only one is venomous to humans. The other six snakes are adapted to living in arid environments without a lot of water.