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.
Today, you’re going to learn about the 4 types of snakes in Idaho!
#1. Prairie Rattlesnake
- Crotalus viridis
- 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!
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.
#2. Terrestrial Garter Snake
- Thamnophis elegans
- 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.
#3. Valley Garter Snake
- Thamnophis sirtalis fitchi
- 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.
#4. Western Rattlesnake
- Crotalus oreganus
- 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.
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!
Do you need additional help identifying snakes in Idaho?
Try this field guide!
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!