Here are Idaho’s 12 snake species. What to know and how to tell which are dangerous

UPDATE (May 24, 2021): Since this article was first published in 2017, Poison Control has reported 44 snakebite incidents statewide. Nearly 82% of those —36 bites — were from venomous species.

Idaho is home to just two venomous snakes: the Western rattlesnake and the prairie rattlesnake. Twenty-seven of the venomous snakebites in Idaho over the past two years are attributed to rattlesnakes, while the remaining nine venomous snakebites are attributed to “unknown crotaline” species, meaning the pit viper family of snakes.

According to the Idaho Department of Health and Welfare, data from the past 22 years shows no Idahoans have died of venomous snakebites during that time.

On average, about a dozen people report snakebites in Idaho each year. No bites have been reported thus far in 2021. Over the past four years, 12 people in the Treasure Valley have reported snakebites. Nine of those were venomous.

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This story was originally published May 29, 2017:

One of the most misunderstood and maligned animals is also one of the most intriguing.

Snakes, said Bill Bosworth, a wildlife biologist with the Idaho Fish and Game, are generally beneficial for humans, even if they’re not beloved.

“They prey on species we regard as pests, mice and rats, as well as insects. They’re rarely a danger to people unless they’re being handled, and then it’s only rattlesnakes,” Bosworth said.

Snakes are often victims themselves. Many are prey for birds and other animals. The biggest local threat to native snakes, Bosworth said, is cars.

Idaho has 12 native snake species. Four are the most common — the Western rattlesnake, North American racer, gopher snake and terrestrial garter snake.

Meet the snakes

▪ Western rattlesnake: Rattlesnakes (the Western and less common prairie) are the only venomous snakes in Idaho. They’re most common in rocky areas, but can swim so they’re sometimes found around water.

They’re distinguishable by the sound of their rattle, a triangular-shaped head and patterned scales that range from tan to brown to gray. A mature rattlesnake is about 3 feet long.

Rattlesnakes are nocturnal and hunt at night by sensing heat from their prey. They are occasionally active during the day, especially during cooler weather. They are vulnerable to heat and are a food source for hawks, so in warmer terrain they will stay in the shade or hide under bushes, rocks or surface debris.

▪ Gopher snake: Gopher snakes 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 gopher snakes for rattlesnakes because when gopher snakes 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.

Gopher snakes do bite, Bosworth said. The bites can be painful, he said, so just leave them alone.

▪ North American racer: Racers are usually out during the day, in dry terrain, including in the Boise Foothills.

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.

They’re notable for the way they move: They’re fast, and have a gliding, rather than undulating, motion, Bosworth said. If you’re in town and see a fast-moving snake, chances are it’s a racer.

▪ Terrestrial garter snake: Garter snakes (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’re distinguishable by their coloration: greenish-brown with small black patches and a pale yellow stripe down their spine. Garter snakes will bite when they’re provoked but they are not aggressive. Adults are usually around 32 inches long.

And you might see ... but you probably won’t

▪ Common garter snake: The common garter snake 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.st

▪ Northern rubber boa: “This is a really cool snake,” Bosworth said. 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. A Northern rubber boa is in residence in Bosworth’s office.

▪ Ring-necked snake: “Arguably our rarest, most beautiful snake,” Bosworth said. The ring-necked snake is small, only around 20 inches long in adulthood. They are gray with a vivid orange underbelly. Some have rings around their necks. Some don’t.

▪ Desert nightsnake: These snakes release venom, but it’s not dangerous to humans, Bosworth said. 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 shape of its head and nose don’t reflect its name, Bosworth said.

▪ 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 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.

This story was originally published May 29, 2017 at 1:26 PM with the headline "Here are Idaho’s 12 snake species. What to know and how to tell which are dangerous."