12 Snakes Found in Idaho (2 are Venomous)

Written by John Alois
Updated: October 8, 2022
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Situated near the northwestern corner of the United States, Idaho has many mountains and forests ideal for snakes, even around the Boise area. Despite this, there aren’t as many different snake species in Idaho as there are in some eastern states. Furthermore, of the 12 species of snake that call the Gem State home, only two are dangerous to humans on account of their venom.

Even though this number is small, it may cause concern for some potential hikers, since humans have a longstanding fear of snakes. However, we don’t think this fear is warranted. The chance of injury from a snake is incredibly low, and even lower for those who know which snakes are dangerous and whether they pose a threat. 

This article aims to inform people which snakes they need to watch out for, how to recognize danger, and which snakes they are more likely to encounter in the wilds of Idaho. Continue reading to learn more about some of the snakes in this state.

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5 Common Snakes in Idaho

The most common snakes in Idaho include garter snakes, gopher snakes, and rattlesnakes. We’ll dive into Idaho’s two venomous snakes in a moment, but first let’s inventory up some of the most common non-venomous snakes in the state. These snakes rarely bite and pose little potential harm to people.

Gopher Snake

Best Pet Snakes
The gopher snake is commonly misidentified as a Rattlesnake because of its markings and defensive behavior. It may hiss loudly, flatten its head, vibrate the tail, and strike when annoyed.

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One of the most common snakes in Idaho, the gopher snake, is also called the bullsnake because of its large size. In fact, at a whopping 67 inches, they are the largest snake in the state. They may inhabit valleys and shrublands and eat most kinds of small mammals and eggs, along with the occasional reptile.

Because of its light coloring and dark blotches, some people freak out when they encounter one in their yard, confusing it for a western rattlesnake. However, there are a few differences to watch out for. First of all, a rattlesnake will, of course, have a rattle, so if you don’t see one, you’re probably fine. Secondly, their eyes are very telling. 

A western rattlesnake will have a cat-like, slit-shaped eye, while the gopher snakes’ are round. That being said, despite being nonvenomous, they have been known to headbutt or, in rare instances, bite. This venomless bite will cause no serious damage, but if you think there is even a chance that it was a rattlesnake, get medical attention as soon as possible.

Terrestrial Garter Snake

Terrestrial garter snakes are small and range across all of Idaho.

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Garter snakes are the most common snake in many U.S. states, and terrestrial garter snakes make their home from the Rockies to the West Coast, including Idaho. Some people will tell you they have six different subspecies since they come in many colors, including brown, green, and black. However, this is currently up for debate in the scientific community. You’ll still find their iconic yellow, orange, or white stripes on the vast majority of adults.

Given its name, you would expect a terrestrial garter snake to make its home on land, and you would be correct. Not only do these snakes occupy grasslands and forests, but they can be found on Idaho’s high peaks up to 13,000 feet above sea level. However, did you know that they are also adept swimmers? 

Part of their diet includes fish, frogs, and tadpoles, and they navigate the streams of Idaho quite well. Since their range is so wide, you will likely encounter one wherever you go. Even though they are almost always peaceful around people, their saliva does possess a weak venom that may cause swelling and irritation. It is best to get this looked at, but you need not fear for your life or limb.

Valley Garter Snake (Common Garter Snake)

Red Valley Garter Snake

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A subspecies of the common garter snake, the valley garter snake is the dominant breed throughout the Pacific Northwest, including the vast majority of Idaho. They can grow to be 55 inches, have black and brown coloring, and, as you may expect, have three yellow stripes along their bodies. 

In addition, this particular garter stands out with the red coloring on its head and parts of its body, along with its yellow belly. Valley garters are extremely adaptable and can be found throughout many areas of Idaho, including forests, grasslands, wetlands, and water. Like terrestrial garters, they are skilled swimmers.

Since they need to regulate their temperature, they spend much of their time under rocks and logs. In the winter, they hibernate communally in any opening they can find, including animal burrows, rock crevices, and even manmade items. In fact, they are quite used to people and often spend time in civilized areas. 

Unfortunately, this comes with a price, as they are often run over and killed out of fear, perhaps because of their color. However, there is little to fear with this snake. It is nonvenomous, and the worst thing it can do to a person is release a gross musk as an absolute last resort upon capture. Thus the valley garter snake is no more dangerous than any other garter.

Venomous (Poisonous) Snakes in Idaho

Idaho is home to two types of venomous snakes. The praire rattlesnake has a much more limited range while western rattlesnakes are found across much of southern Idaho.

Prairie Rattlesnake

Snakes in Idaho - Prairie Rattlesnake
Praire rattlesnakes are most commonly found in the Frank Church wilderness area

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The prairie rattlesnake is one of two venomous snakes that reside in Idaho. This snake is common in grasslands, forests, and shrublands throughout the Midwest. However, they migrate in winter when they find a cave, crevice, or burrow and hibernate there with others of their kind. This migration may be as much as 7 miles from their hunting grounds.

They can reach a length of 3 to 5 feet and come in many colors, including olive green, brown, and yellow. Along its body are dark blotches that turn into rings closer to the tail. Their eyes are elliptical, which means that they look like slits, similar to a cat’s eye. As a bite from this snake can be quite deadly, it helps to be able to identify one in the wild. 

That being said, the prairie rattlesnake isn’t inherently aggressive. In fact, if you enter its territory, it is likely to freeze in place in hopes of blending into its surroundings, or it may simply slither away. However, if someone is foolish enough to follow it, it will coil and rattle. This is your last chance to back off before it strikes, so please do so. This rattlesnake will not look for trouble, so avoiding it avoids any risk altogether.

Western Rattlesnake

Largest Rattlesnake
Western Rattlesnake coiled with rattle erect and forked tongue extended.

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The other venomous snake in the state, the western rattlesnake, is more common, as its range covers much of southern and western Idaho. The snake is also called the northern Pacific rattlesnake and can have multiple appearances. Some western rattlesnakes have a dark coloring with light blotches, and others a light color with dark blotches. In this sense, they almost look like each other’s inverse. Other than coloring, however, western rattlesnakes share most things in common. They have triangular heads, stripes from their eyes to mouths, and a length of 6 feet.

As far as habitat goes, the western rattlesnake is quite versatile. They prefer rocky areas but may also be found in grasslands. On top of that, they may be active at any hour of the day, and they can even swim. Their prey includes small animals like mice, birds, and lizards, and they curl up in wait while looking for their chance to strike. 

As with most rattlesnakes, their telltale rattle is a last-ditch effort to avoid battle with a predator, so back off if you hear one. Even though most rattlesnake bites are “dry bites,” meaning that they don’t inject any venom, you don’t want to take any chances, so please seek medical attention immediately.

A Complete List of Snakes in Idaho

Here is a list of every snake you’ll find in Idaho with a brief description of its range:

  1. Rubber boa – Ranges across all of Idaho
  2. Common garter snake – Ranges across all of Idaho
  3. Striped whipsnake – Bottom third of the state
  4. Gopher snake – Most of Idaho except for northern counties
  5. Western terrestrial garter snake – Ranges across all of Idaho
  6. Racer – Most of Idaho except for northern counties
  7. Western Ground Snake – Treasure Valley
  8. Night snake – Bottom third of the state
  9. Longnose snake – Treasure Valley
  10. Ringneck snake – Isolated pockets that include near I-84 on the Utah boarder and near the Washington and Oregon borders
  11. Western rattlesnake – Lower three-quarters of the state
  12. Praire rattlesnake – Central Idaho

In Conclusion

If you take anything away from this list, please remember that no snake in Idaho actively hunts humans. In fact, they fear them as potential predators. 

They only strike back in retaliation if backed into a corner and feel that striking is their only chance at escape. So if you see or hear a rattlesnake, the best thing you can do is stay calm and leave them alone. About six people in the United States die every year from snake bites, which is remarkably low when you think about how common they are.

That being said, it can sometimes be challenging to tell all of these snakes apart from each other, and even the nonlethal ones can irritate the flesh they bite. If a snake of any kind bites you, we recommend that you seek medical attention out of an abundance of caution. However, it’s still rare to be bitten by any of Idaho’s snakes. As long as you respect your surroundings, you should have little to fear, and you can enjoy the wilds of Idaho to your heart’s content!

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