There are A LOT of snakes in Wyoming!
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 Wyoming 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 10 types of snakes in Wyoming!
#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 Wyoming 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. Red-sided Garter Snake
- Thamnophis proximus parietalis
- Normally dark green to black, but color varies.
- Three yellow stripes; one down the back and one down each side.
- As the name suggests, red or orange bars run along their sides between the yellow stripes.
- Subspecies of the Common Garter Snake.
Like other garter snakes, they are habitat generalists. Look for them in a few small pockets in Wyoming in forests, shrublands, wetlands, fields, and rocky areas. Their favorite foods include frogs, earthworms, and leeches! YUM! 🙂
In some areas, after emerging from hibernation, there are not enough females for all the males. In these cases, “mating frenzies” occur, and dozens and dozens of these snakes can be found together.
To survive colder months, Red-sided Garter Snakes have to hibernate BELOW the frost line. Depending on the area they are located in, it can be hard to find suitable locations. So the few adequate hibernation dens can shelter hundreds, even thousands, of snakes! To see an example, watch the video below:
#3. 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 Wyoming!
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 Wyoming 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.
#4. Plains Garter Snake
- Thamnophis radix
- Adults average 36 inches in length.
- Coloration is gray-green with a distinctive orange stripe down the back and a greenish-yellow stripe down each side.
- Distinct light yellow spots on the very top of the head!
Plains Garter Snakes are almost always found in eastern Wyoming in prairies and grasslands near freshwater sources. They have a fairly large population and adapt well to human-modified landscapes. You may spot them near abandoned buildings, trash heaps, or vacant lots.
This species is considered one of the most cold-tolerant of all snakes! In fact, they will even come out of hibernation on warmer winter days.
Plains Garter Snakes feed primarily on earthworms, slugs, and small amphibians. However, they have also been observed preying on small mammals and birds, including the Eastern Meadowlark and Bank Swallow.
#5. 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 western Wyoming 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.
#6. Western Milksnake
- Lampropeltis gentilis
- Adults typically range from 15 to 34 inches in length.
- Coloration is whitish, black, and reddish or orange bands, with the reddish-orange bands being bordered by black.
- The snout is blackish and sometimes features white flecking, and the underside may have extensions of the bands or be more whitish.
Western Milksnakes are found in parts of Wyoming in open sagebrush, grasslands and are occasionally seen in suburban areas. They’re a secretive species frequently found under objects like rocks, logs, boards, and other debris.
Western Milksnake Range Map
Because of their coloration, they are often confused with venomous coral snakes. But luckily, there’s an easy way to tell the difference. Just remember this rhyme:
“If red touches yellow, you’re a dead fellow; if red touches black, you’re all right, Jack.”
These snakes aren’t picky about food and feed on small mammals, birds, bird eggs, other snakes, lizards, reptile eggs, and occasionally, worms and insects. They actively hunt down their prey and use their coils to constrict the life out of them.
Though they’re usually docile when handled, Western Milksnakes do exhibit strong defensive behaviors when disturbed. You can expect them to vibrate their tail (like a rattlesnake), and they may even rear up and strike!
#7. Smooth Greensnake
- Opheodrys vernalis
- Adults are SLENDER and typically range from 14 to 20 inches in length.
- Coloration is uniformly light green with a yellow or white underside and a red tongue with a black tip.
- Juveniles may be olive-green, blue-gray, or even brown until they shed their skin for the first time.
Also called Grass Snakes, these bright green snakes can be found in marshes, meadows, pastures, savannas, open woods, and along stream and lake edges. They prefer moist areas near permanent water sources.
Smooth Greensnake Range Map
They prey almost exclusively on insects and spiders and don’t use constriction; instead quickly striking and swallowing their prey alive.
Smooth Greensnakes hibernate during the winter in Wyoming, seeking shelter in old mammal burrows and abandoned anthills. They often hibernate communally with other small snakes. They emerge in the spring, typically in April, and are active until October.
Smooth Greensnakes rely on their EXCELLENT camouflage to avoid predators. They’re also agile and can flee quickly if they must.
- Pituophis catenifer sayi
- Adults are large and typically range from 4 to 6 feet in length.
- Coloration is yellow, beige, or light brown with large brown, black, or reddish blotching on the back and three sets of small blotches on the sides.
- Blotches may appear like bands near the end of the tail, and the underside is yellowish with black spots.
These snakes are often seen in Wyoming in areas with high rodent populations.
So they’re common in places like prairie dog towns. But you can also find Bullsnakes in fields, grasslands, forest edges, savannas, and brushlands with sandy soils.
Bullsnakes are fast and can actively pursue prey in loose soil. They even use their prominent rostral (nose scale) to dig! Once they’ve captured their prey, they use their strong body to coil around and constrict their prey.
Despite being nonvenomous, these snakes act aggressively toward any threats. They often lift the front half of their body, hiss, and lunge at their attacker until they feel they can retreat.
Interestingly, their hissing can sound like a rattle! (see below!)
To accomplish this, the snake forces air through an extension of the windpipe, which has a piece of cartilage called an epiglottis that flaps back and forth, sounding very similar to a rattlesnake.
#9. Plains Hog-nosed Snake
- Heterodon nasicus
- Adults range from 15 to 39 inches in length.
- Coloration is varying shades of brown with darker brown blotches on the back, two alternating rows of smaller dark spots down the sides, and large longitudinal blotches on the sides of the neck.
- Enlarged rostral (nose) scale.
The Plains Hog-nosed Snake strongly prefers open sandy or gravelly habitats in Wyoming. They’re excellent burrowers and also use old animal burrows for hibernation and protection from hot temperatures.
These snakes are best-known in Wyoming for their displays when disturbed!
When initially confronted, Plains Hog-nosed Snakes typically remain motionless or hide their head under their coils. They may also try to bury themselves or escape into a burrow.
However, if they’re further disturbed, they’ll spread their jaws and neck like a cobra and puff up their bodies. They may also hiss loudly and deliver false strikes with a closed mouth.
If these intimidating displays fail, the Plains Hog-nosed Snake will then twist as though they’re in pain, roll over on their back and play dead. They’ll be limp, open mouthed, and will remain this way even if picked up. They may also bleed from the mouth and cloaca, expel musk and fecal matter, and regurgitate recently eaten food.
If I saw one of these snakes do this display, I’d definitely leave it alone! But, unfortunately, they’re sometimes killed by people who are frightened by their cobra-like posture.
#10. Midget Faded Rattlesnake
- Crotalus oreganus
- Adult size varies widely over their range, with the largest individuals being 6 feet in length.
- Coloration is tan, yellow, and rarely pinkish. Faint oval blotches.
- Triangular head, heat-sensing pits between the eyes and nostrils, dark stripe with white borders that runs from the eye towards the jaw.
- Midget Faded Rattlesnakes are subspecies of the Western Rattlesnake.
This venomous snake, which is a subspecies of the Western Rattlesnake, can be found in southwest Wyoming. They can be found in mountainous areas, woodlands, and grasslands. They also often occur in close proximity to humans.
Midget Faded Rattlesnakes 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 Wyoming?
Try this field guide!
Which of these SNAKES have you seen before in Wyoming?
Leave a comment below!
Also, if you enjoy this article, make sure to check out these other Wyoming guides!