There are A LOT of snakes in Idaho!

And what’s interesting is that they are all incredibly unique and have adapted to fill many habitats and niches.

You’ll see that the snakes that live in Idaho are very different from each other.

For example, some species are venomous, while others use constriction to immobilize their prey. Or the fact that certain snakes are rarely seen because they spend most of their time underground, but others are comfortable living EXTREMELY close to humans.

8 types of snakes in Idaho!

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#1. Prairie Rattlesnake

• Crotalus viridis

Identifying Characteristics:

• Adults typically range between 3.3 and 5 feet in length.
• Coloration is highly variable and can be greenish-gray, olive green, greenish-brown, light brown, or yellow. All variations have dark blotches on the body that turn into rings near the tail.
• Broad triangular head, elliptical pupils, heat-sensing pits between the eyes and nostrils, and a tail rattle.

These venomous snakes can be found in Mideast Idaho in open prairies, grasslands, semi-desert shrublands, and forested environments. They can even be found at elevations up to 9500 feet!

Prairie Rattlesnake Range Map

The Prairie Rattlesnake hibernates during the winter, often in communal dens. These dens are typically rock crevices, caves, or old mammal burrows. Individual snakes return to the same den each winter and migrate up to seven miles to their hunting grounds in the spring.

When they feel threatened, these snakes freeze to use their camouflage to avoid detection. They may also quietly crawl away to cover. If approached, they may coil and rattle their tail as a warning before striking. Their potent venom has both hemotoxic and neurotoxic properties, and although rare, can be fatal to an adult human.

Prairie Rattlesnakes are listed on the ICUN Red List as a species of least concern. However, they are considered threatened and declining in parts of their range. In addition, they have faced pressure from habitat fragmentation and hunting.

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#2. Terrestrial Garter Snake

• Thamnophis elegans

Identifying Characteristics:

• 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 snake can be difficult to identify in Idaho!

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 are great swimmers!

This species is the only garter snake in Idaho 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.

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#3. Valley Garter Snake

• Thamnophis sirtalis fitchi

Identifying Characteristics

• 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 snakes in Idaho 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, and manmade spaces such as foundations and cisterns.

When disturbed, Valley Garter Snakes 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.

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#4. Western Rattlesnake

• Crotalus oreganus

Identifying Characteristics:

• Adult size varies widely over their range, with the largest individuals being 6 feet in length.
• Two subspecies live in Idaho – Northern Pacific and Great Basin.
• Triangular head, heat-sensing pits between the eyes and nostrils, dark stripe with white borders that runs from the eye towards the jaw.

You can find two different subspecies of the Western Rattlesnake in Idaho, and they look completely different. The Northern Pacific variety is dark brown or black with lighter-edged blotches. Great Basin Rattlesnakes are typically pale yellow, light gray, or tan, with brown and blackish blotches.

Western Rattlesnake Range Map

This venomous species occupies a wide range of habitats in Idaho. They can be found in mountainous areas, woodlands, and grasslands. They also often occur in close proximity to humans.

These snakes may be active during the day or night and are often curled, waiting to ambush a variety of prey. They’ll feed on small mammals, birds, reptiles, and amphibians. They may also eat bird eggs, and young snakes often feed on insects.

Like other rattlesnakes, this species gives birth to live young. Healthy, sexually mature females can give birth to litters of up to 25 babies!

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#5. North American Racer

• Coluber constrictor

Identifying Characteristics:  

• Adults typically range from 50 to 152 cm (20 to 60 in) in total length  

• The patterns and texture of their skin vary widely among subspecies. However, most are solid-colored and have a lighter-colored underbelly.

True to their name, North American Racers are one of the FASTEST snakes in Idaho!

When they get moving, they can speed away at up to 3.5 miles per hour (5.6 kph). These active snakes are curious and have excellent vision. In fact, they are known to raise their heads above the height of the grass to view their surroundings.  

Despite their scientific name (constrictor), North American Racers do not squeeze their prey to death. Instead, they subdue their victim by holding it down with their body. Smaller prey is simply swallowed alive.

North American Racer Range Map

These nonvenomous snakes fight back incredibly hard if they feel threatened or become trapped. You can expect them to bite, thrash, defecate, and release a foul-smelling musk, especially if you try holding one. In addition, racers will try to impersonate rattlesnakes by shaking their tails in dry leaves.  

North American Racers are still abundant in many places. But they face threats as they are losing habitat to urbanization and development. Unfortunately, many people also kill them out of fear, even though they are completely harmless, especially if you leave them alone. 

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#6. Ring-necked Snake

• Diadophis punctatus  

Identifying Characteristics:  

• These snakes are usually solid olive, brown, bluish-gray, or smoky colored. Look for a distinctive yellow or red neckband.   
• The snake’s head color is usually slightly darker than the rest of the body, tending towards black rather than gray or olive.  
• Adults are usually between 25-38 cm (10-15 in) long.  

It can be hard to find these snakes in Idaho!

That’s because Ring-necked Snakes are VERY secretive and spend most of their time hiding in areas with lots of cover. In addition, they are nocturnal and rarely seen during the day.

Ring-necked Snake Range Map

The colors represent the different subspecies of Diadophis punctatus.

If you come across one, you may see its unique defense posture. Red-bellied Snakes will curl their tails and expose their bright red-orange bellies when they feel threatened in hopes of scaring you away.

Ring-necked Snakes mostly eat small salamanders, earthworms, and slugs. Not much is known about their population status because they are so hard to find!

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#7. Striped Whipsnake

• Masticophis taeniatus  

Identifying Characteristics:  

• Adults are between 30-72 inches (76-183 cm) in total length.  
• The coloration on their back is black, dark brown, or gray with an olive or bluish tint.  

The Striped Whipsnake can be found in a diverse range of habitats in Idaho.

Look for them in such places as grasslands, shrublands, woodlands, canyons, and open pine-oak forests. They can even be found in the mountains!

Striped Whipsnakes are active and alert during the day. They are incredibly fast and prey on a wide range of species, including lizards, small mammals, young birds, frogs, insects, and other snakes (including venomous rattlesnakes).

These snakes are nonvenomous and pose no danger to humans. Their two main threats are the loss of natural habitat due to expanding agriculture and vehicle collisions. 

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#8. Northern Rubber Boa

• Charina bottae

Also known as the Coastal Rubber Boa.

Identifying Characteristics:  

• Adults are between 38-84 cm (1.25 to 2.76 ft.) long.
• They have smooth and shiny scales, and their skin is typically tan to dark brown with a lighter belly.
• One of the most noticeable features of rubber boas is their short and blunt tails, which are often confused for their heads.  

As the name suggests, rubber boas get their name from their loose, wrinkled skin that looks and feels like rubber.   

Northern Rubber Boas can thrive in diverse habitats in Idaho, ranging from grasslands, meadows, and chaparrals to deciduous and coniferous forests and high alpine environments. One place you WON’T find this snake is in hot and dry areas, as they cannot tolerate higher temperatures.

The best place to find one is typically under shelter, such as rocks, logs, leaf litter, and burrows.   

Northern Rubber Boas are often used to assist individuals in overcoming their fear of snakes. These gentle snakes never attempt to strike or bite humans under any circumstances. However, on rare occasions, they might emit a strong musk from their vent if they sense danger.  

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Do you need additional help identifying snakes in Idaho?

Try this field guide!

• Peterson Field Guides to Reptiles and Amphibians

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Which of these SNAKES have you seen before in Idaho?

Leave a comment below!

Also, if you enjoy this article, make sure to check out these other Idaho guides!

• 6 FROGS Found in Idaho! (ID Guide)

• 3 Types of TOADS in Idaho!

• 11 Kinds of LIZARDS That Live in Idaho!