Snakes in Idaho, What’s Poisonous & What’s Harmless (With Photos)

We love Idaho and love the great outdoors that the gem state has to offer. Inevitably however, if you are outdoors enough, you will encounter a snake two. While many will run away from anything that slithers, it is helpful to know which snakes are common in Idaho and which ones are dangerous in Idaho.

Last summer, near Bonneville hot springs I had a snake slither up the back of the rock I was sitting on and it started to crawl up my back (just a little) before realized what I just felt and jumped up. Then just yesterday while playing near black canyon recreation area near Emmett a snake was slithering around right near our truck. I wanted to make sure I could identify these Idaho natives for when I encounter them again. According to the Idaho Statesman and Idaho Fish and Game, here are the types of snakes you are likely to encounter in Idaho.

Western rattlesnake: Rattlesnakes are the only poisonous snakes in Idaho. They’re most common in rocky areas, but can swim so they’re sometimes found around water. They are mostly nocturnal and hunt at night by sensing heat from their prey. They have a triangular-shaped head and patterned scales that range from tan to brown to gray. A mature rattlesnake is about 3 feet long and of course has a rattle.

North American racer: Racers are usually out during the day, in dry terrain, including in the Boise Foothills. They are fast. When they’re first born, they are speckled brown. As they mature, they lose their patterns and turn greenish-gray in color with a yellow belly. Adults are typically around 32 inches long.

Gophersnake: Gophersnakes are common in the Boise Foothills. They like warm, dry areas as well as forested areas. They’re also known as bullsnakes. People commonly mistake gophersnakes for rattlesnakes because when gophersnakes feel threatened, they impersonate rattlers by hissing and flicking their (rattle-less) tails. They even can flatten their heads to appear more triangular. Their markings, dark-colored patches, are also similar to those on rattlesnakes. Adults can grow to around 42 inches long. They do bite and it can be painful but not poisonous.

Terrestrial gartersnake: (terrestrial and common) are the most aquatic snakes in Idaho. They are often found near water where they feed on small fish and tadpoles. They are also found in drier habitats. They greenish brown with small black patches and a pale yellow stripe down their spine.

Get our free mobile app

Common gartersnake: The common gartersnake is actually less common than the terrestrial garter. It, too, is aquatic and more brightly colored. In addition to the yellow stripe down its back, it has bright red on the sides of its body.

Northern rubber boa: It lives in forested, rocky areas and spends much of its life underground. This native boa is distinguishable by its color, ranging from pale olive green to blackish, with a yellow belly. The rubber boa moves slowly and has a blunt tail. It has been called the “two-headed snake,” Bosworth said, because the blunt tail resembles a second head. This snake typically feeds at night by raiding nests of mice and rats.

Ring-necked snake: They are gray with a vivid orange underbelly. Some have rings around their necks. Some don’t. They are smaller with adults getting to about 20 inches.

Desert nightsnake: These snakes release venom, but it’s not dangerous to humans. Nightsnakes use their venom to subdue the lizards they eat. They live in desert habitats and are highly nocturnal. Their colors range from tan to brown. They are even smaller than ring-necks, measuring 18-20 inches as adults.

Western groundsnake: This is another small, nocturnal snake notable for its flashy coloration: bands of lipstick red and black. Western groundsnakes are mostly found around the Snake River in Owyhee County.

Long-nosed snake: Found mostly along the Snake River corridor in Owyhee and Ada counties, the long-nosed snake is very rare. It’s notable for its black and white speckled bands. The snake doesn’t actually have a long nose despite the name.

Striped whipsnake: This is another long, slender snake that’s out during the day (note its relatively large eyes for daytime hunting of insects, lizards and even other snakes) and is related to the North American racer. It’s found in the lower elevations, dry foothills and shrub habitats, but is not common. Its distinct coloration: the underside of its tail is pink.

Prairie rattlesnake: Idaho’s other native rattlesnake. It’s mostly found in Central Idaho, especially in the Frank Church wilderness area. It’s only been identified as a species separate from the Western rattler in the last 15 years. This species has similar looks and habits to the Western rattlesnake.