Are There Water Snakes in Idaho?

Snakes belonging to the Genus Nerodia are considered true water snakes and spend the majority of their lives in water. While Idaho has a dozen native snake species, none of them are technically water snakes that fit into this category. The main reason there are no water snakes in Idaho involves the state’s vast expanses of mountainous, rocky terrain where snakes evolved to survive without easy access to water.

Many snakes in Idaho are semi-aquatic or terrestrial snakes that can go for long periods without water. They survive by relying on creases in their lower jaw skin to fully absorb even the smallest amount of water. These same creases allow snakes to expand their lower jaws when swallowing prey larger than their entire head!

In addition, snakes have an amazing ability to keep their skin hydrated in the absence of water sources. If a droplet of water falls on their skin, the scales covering the skin force the droplet to break into thousands of smaller drops that seep into microscopic channels contained in each scale. So, instead of simply rolling off a snake’s skin, water droplets stay inside the scales until the snake needs to suck on the scales for water.

Since there are no water snakes in Idaho, this article will delve into a few of the other species of snakes found throughout the Gem State.

7 Semi-Aquatic and Terrestrial Snakes in Idaho

Here are seven snakes living in various areas of Idaho. Some are considered aquatic or semi aquatic like the garter snake, which is actually closely related to water snakes. 

1. Rubber Boa

• Scientific name: Charina bottae
• Length: 1 ft to 3 ft
• Venomous: no

Commonly seen in meadows, grasslands, and forests, rubber boas thrive in Idaho, Montana, Utah, and Oregon. Rubber boas differ from other snakes because they prefer cooler climates found in northwestern areas of the U.S. In fact, rubber boas cannot survive in the hot, humid climates preferred by true water snakes.

Spending most of their time under logs, rocks, and other shelter types that provide shade, rubber boas come out at night to hunt small voles, shrews, and deer mice. Idaho’s frigid winters send rubber boas into their dens to hibernate until spring.

2. Common Garter Snake

• Scientific name: Thamnophis sirtalis
• Length: up to 4 ft
• Venomous: no

Although Massachusetts has named the common garter snake as their state reptile, you’ll find these slender, striped snakes inhabiting forests, ponds, meadows, and streams throughout Idaho. Stripe colors range from yellow, brown, and gold to blue, green, and red.

Common garter snakes are not venomous to humans, but their saliva can be toxic to rodents and amphibians. Bites to humans are not toxic, but the bite site often swells and burns for several hours afterward. Common garter snakes in Idaho eat earthworms, slugs, crayfish, leeches, fish, and, of course, rodents.

3. Western Ground Snake

• Scientific name: Sonora semiannulata
• Length: 7 inches to 20 inches
• Venomous: no

Idaho’s drier, rockier areas are where you’re more likely to find the western ground snake, a small, smooth-skinned snake that can have brown or orange striping or a solid-colored body. A strictly nocturnal snake that hunts centipedes, spiders, crickets, and grubs at night, the western ground snake’s ability to hide so well during the day leaves it with only one enemy, for the most part–other snakes!

Since the western ground snake’s head and teeth are extremely small, getting bitten by one isn’t likely to puncture human skin.

4. Western Rattlesnake

• Scientific name: Crotalus oreganus
• Length: 25 inches to 60 inches
• Venomous: yes

Found only in the lower half of Idaho, the western rattlesnake is nearing endangered status due to human persecution, habitat loss, and traffic. Recognizable by the dark splotches encircled with whitish halos extending along their backs, western rattlesnakes have vertical pupils, triangular heads, and a “rattle” at the end of their tails.

Like most other snakes, they prey on mice, shrews, rats, voles, and small birds. Excellent at hiding themselves in foliage, western rattlesnakes will not attack humans.

They only bite if cornered or threatened. Although their bite is rarely fatal to humans, it will cause intense pain and require quick medical treatment.

5. Gopher Snake

• Scientific name: Pituophis catenifer
• Length: 35 inches to 96 inches
• Venomous: no

Inhabiting most of Idaho except for a few northern counties, the gopher snake is powerful, large, and often mistaken for a rattlesnake. Their coloring depends predominantly on where they live in Idaho.

Gopher snakes living near urbanized areas may be light brown and less blotchy in color than gopher snakes living in forested or rocky areas. However, nearly all gopher snakes have pale, sometimes freckled undersides.

Like rattlesnakes, gopher snakes may vibrate their tails, flatten their heads, and hiss when threatened by humans. While getting bitten by a gopher snake will hurt, their bite is not toxic to humans or animals.

6. Long-nosed Snake

• Scientific name: Rhinocheilus lecontei
• Length: 22 inches to 33 inches
• Venomous: no

The long-nosed snake is aptly named–it has a distinctive, slightly upturned, lengthy snout that it uses to burrow into the ground and hide during the day. Its tri-colored skin consists of bright red and black bands and a cream-colored belly that resembles the venomous coral snake’s markings.

However, the long-nosed snake does not have a venomous bite but it will eject a horrible-smelling spray of blood and musk from an opening near the tail when threatened. Long-nosed snakes prefer to feed on amphibians, smaller snakes, and lizards rather than rodents. Idaho’s shrublands and grasslands is where you’ll find the long-nosed snake either hunting at night or resting between dawn and dusk.

7.  North American Racer

• Scientific name: Coluber constrictor
• Length: 20 inches to 65 inches
• Venomous: no

Active during the day and night, the North American racer lives in grasslands and scrublands where it can slither at high speeds to catch prey. Unlike many other snakes that rely on constriction to kill food, the North American racer simply swallows small mammals, insects, and lizards whole. When threatened, the racer vibrates its tail.

Humans who try to capture a racer will likely be bitten and sprayed with a foul-smelling substance containing excrement. During winter, North American racers hibernate in rock crevices and burrows abandoned by mammals. The Idaho Classification of Wildlife Department lists the North American racer as a “protected nongame” reptile.