17 Common Reptiles in Colorado (W/Pics!)
Are you wondering what reptiles you can find in Colorado?
This is a great question! Although these reptiles are widespread, they can be difficult to find. Most reptiles, including snakes, turtles, and lizards, are secretive and shy. But observing and finding reptiles is a really fun experience!
Below you will find a list of the most common and interesting reptiles that live in Colorado. In addition, you will find detailed pictures, along with range maps for each species to help with your identification!
And if you’re looking for a more comprehensive list of specific reptiles like snakes, lizards, or turtles, check out our ID guides to these fascinating creatures!
14 Common SNAKES That Live in Colorado! (ID Guide)
16 Common LIZARDS Found in Colorado! (With RANGE MAPS)
17 COMMON Reptiles in Colorado:
#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.
- They have a broad triangular head, elliptical pupils, heat-sensing pits between the eyes and nostrils, and a tail rattle.
Prairie Rattlesnakes have a more varied habitat than many reptiles in Colorado. These venomous snakes can be found 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 Prairie Rattlesnakes may also quietly crawl away to cover. If approached, they 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.
#2. Northern Watersnake
- Nerodia sipedon sipedon
- Adults range from 24 to 55 inches in length.
- Coloration is pale grey to dark brown with reddish-brown to black bands.
- Large adults become darker with age and appear almost plain black or dark brown.
- Females tend to be larger than males, and coloration is most vivid in juvenile and wet individuals.
Northern Watersnakes are one of the most common reptiles in eastern Colorado!
Northern Watersnakes prefer slow-moving or standing water like ponds, lakes, vernal pools, marshes, and slow-moving rivers and streams. They’re often seen basking on rocks or logs in or near the water.
Northern Watersnake Range Map (Yellow area below)
Credit: Virginia Herpetological Society
These reptiles primarily feed on fish and amphibians by hunting along the water’s edge and shallow water during the day. They grab their prey and quickly swallow while it’s still alive!
While non-venomous, they can deliver a painful bite!
Their saliva contains a mild anticoagulant that can cause bites to bleed, making the injury appear worse. These important defense mechanisms help water snakes survive predators such as raccoons, snapping turtles, foxes, opossums, other snakes, and birds of prey.
#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.
Although they’re common in western Colorado, these reptiles can be difficult to identify!
Even trained herpetologists have issues! Its coloration varies widely, and there are believed to be six 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 reptiles are great swimmers!
This species is the only garter snake 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 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.
- The 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 live 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 reptiles! 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.
- 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.
Bullsnakes are often seen in areas with high rodent populations.
So they’re common in places like prairie dog towns. But you can also find them in fields, grasslands, forest edges, savannas, and brushlands with sandy soils.
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. This body language is reminiscent of other reptiles in eastern Colorado, like prairie lizards!
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.
#6. Six-Lined Racerunner
- Aspidoscelis sexlineata
- 2.25 to 3.75 inches long from snout to vent (length does not include the tail).
- “Dark fields,” or broad stripes in between lighter stripes on whiptails, are brown to black.
- 6-8 light stripes vary in color from white or yellow to gray-blue.
- The coloring is much brighter in males, with greens on the back and light turquoise on the belly.
This reptile is easy-to-spot in eastern Colorado.
Six-Lined Racerunners are insectivores, and their primary food source is termites. However, they also eat beetles, ants, and spiders, so these small whiptails can be handy if you have a pest problem.
The Six-Lined Racerunner lives up to its name, clocking speeds up to 18 miles per hour! They have no problem outmaneuvering predators and curious humans!
#7. Western Whiptail
- Aspidoscelis tigris
- 2.5 to 5 inches long from snout to vent (length does not include the tail).
- Body coloring is gray-brown to yellowish, with dark bars or spots that form a web-like pattern.
- Skin folds are present on the neck, making the throat appear wrinkled.
- Rust-colored patches are often present on the sides of the belly.
You can find this reptile in western Colorado in sandy, rocky, or firmly packed soil.
Their habitat preferences range from open forest to arid scrubland. Western Whiptails eat other reptiles, scorpions, spiders, termites, and beetles. As you can see, this lizard is anything but picky!
Their physical characteristics and habitats are so varied that there are sixteen distinct subspecies! As you can see in the map above, five subspecies are present throughout the Southwest.
#8. Common Sagebrush Lizard
- Sceloporus graciosus
- 1.9 to 3.5 inches long from snout to vent (length does not include the tail).
- Coloring is gray or brown with a light stripe on each side, a black bar at the shoulder, and blue patches on the belly.
- They have unusually long, almost spidery back claws.
As the name suggests, look for this common reptile in sagebrush in western Colorado.
Common Sagebrush Lizard Range Map:
Common Sagebrush Lizards eat a wide variety of insects and even scorpions! They hibernate during winter when temperatures drop, and food becomes scarce.
The easiest way to tell if you’ve found a Common Sagebrush Lizard is to look at its belly. The brilliant blue spots on its throat and abdomen are a dead giveaway!
#9. Prairie Lizard
- Sceloporus consobrinus
- 3.5 to 7.5 inches long from snout to vent (length does not include the tail).
- The coloring is light reddish-brown with a light brown stripe down the spine.
- Orange or red coloring on the lips and chin is sometimes present.
Look for Prairie Lizards in habitats with lots of places to perch, including open forests, tall grass fields, or even dunes. Their diet is made up of insects and spiders they can easily subdue.
Prairie Lizard Range Map:
These spiny lizards are one of the best climbers of any reptile in eastern Colorado! Prairie Lizards spend most of their time off the ground perched in trees, on fences, and even on sunflowers.
In addition to climbing, Prairie Lizards can run so fast that they’re hard to catch. So if you see one, you’ll probably have more luck observing from a distance than trying to get up close!
#10. Great Plains Skink
- Plestiodon obsoletus
- Adults are up to 13 inches long.
- Coloring ranges from light gray or olive to tan with darker brown markings.
- The tail and feet are usually pale yellow or orange, and the belly is often marked with salmon.
- Young individuals are black with an iridescent blue tail and gold spots on the head.
Great Plains Skinks are frequently found in prairie grassland with open, low-growing plants. However, they occasionally also live in woodland or semi-arid desert areas.
Great Plains Skinks are very aggressive if threatened!
They hide under rocks, shrubs, or logs but are likely to bite if they are disturbed or handled. So, observe with caution! They’re also aggressive hunters and eat insects, snails, spiders, and even other reptiles.
#11. Greater Short-Horned Lizard
- Phrynosoma hernandesi
- 1.75 to 4.75 inches long from snout to vent (length does not include the tail).
- Coloring is beige, tan, or reddish, speckled with white. There are large brown blotches on the neck and sides.
- Horns are short and stubby, located on the back of the head and each side.
Greater Short-horned Lizards prefer to live in shortgrass prairies and the foothills of the Rocky Mountains. Their habitat is semi-arid, with long dry spells and infrequent rain.
Greater Short-horned Lizard Range Map:
Ants are a primary food source for Greater Short-horned Lizards, but they have a varied diet.
They are one of the few reptiles in Colorado that gives birth to live young!
And you may not believe this, but they can produce up to 48 babies in one birth!
#12. Common Side-Blotched Lizard
- Uta stansburiana
- 1.5 to 2.5 inches long from snout to vent (length does not include the tail).
- Coloring is brownish, occasionally blue-gray, with a blue to black blotch on either side of the chest.
- This species often has white speckles dotting its back in the light color phase.
Common Side-blotched Lizards are comfortable in many different habitats. They’re abundant in their range and easy to find by concentrating on the ground where they spend most of their time.
There are three separate morphs of the male Side-Blotched Lizard, and interestingly, this plays a huge role in the mating habits of this species.
They employ a Rock-Paper-Scissors mechanism, with one morph being dominant over the second (like paper over rock) but not over the third (like scissors cutting paper). This unique mechanism causes a “rotation” of the most common morph each breeding season! The three morphs are pictured below:
#13. Eastern Collared Lizard
- Crotaphytus collaris
- 3-4.75 inches long from snout to vent (length does not include the tail).
- Coloring is variable: greenish-blue, olive, brown, or yellow are common. Females are generally darker and less colorful.
You can find eastern Collared Lizards in desert shrubland, open forest, and grassland. They prefer areas with rocks, open space, and lots of sunlight. Like other reptiles in Colorado, this species is cold-blooded and uses the sun to warm itself.
The Eastern Collared Lizard is wildly territorial!
In addition, they’re also powerful predators! Their sharp teeth and strong jaws make catching a meal easy. As a result, they have been known to eat large insects, reptiles, and even other Collared Lizards!
#14. Common Snapping Turtle
- Chelydra serpentina
- They weigh 10 to 35 lbs. and grow 8 to 18 1/2 inches long.
- The snapping turtle has a long tail, chunky head, and large webbed feet.
- The carapace (upper shell) coloring is black, brown, or olive with no distinct pattern.
These prehistoric-looking reptiles are widespread throughout eastern Colorado.
Look for them living in marshes, lakes, ponds, rivers, and slow streams. They prefer areas with plenty of aquatic vegetation to hide in and insects, fish, frogs, and birds to eat.
Snapping Turtle Rangemap:
Credit: Virginia Herpetological Society
Snapping Turtles are best known for their powerful jaws. While there aren’t any recorded incidents of one of their bites causing amputation to a person, it can cause infections serious enough to require an amputation. In fact, their jaws are so strong that snapping turtles commonly eat other turtles!
These reptiles are usually docile but will become very aggressive if removed from the water. One of the best ways to calm an aggressive individual is to place it back into the water, where it can feel safe. I know I have personally picked them up with a large snow shovel to get them off the road and back to safety!
15. Painted Turtle
- Chrysemys picta
- 2.5 to 10 inches long.
- The carapace is low to the ground and generally dark brown or black.
- As the name suggests, they have distinctive yellow, green, and red striping on the carapace, head, and limbs.
The Painted Turtle is one of the most recognizable reptiles in eastern Colorado!
Look for its beautiful coloring of bright reds and yellow greens on its shell, limbs, and head. Painted Turtles live near calm, shallow water. They are attracted to areas with plenty of aquatic plants, their primary food source.
Painted Turtle Rangemap:
It’s almost impossible to accurately assess the population of Painted Turtles in Colorado. Many people keep them as pets and then release them into the wild, causing an ever-expanding range and unstable reproduction rates. These released reptiles can also put pressure on natural populations.
In the wild, Painted Turtles can hold their breath for up to 30 hours!
They also can remain dormant in near-freezing water for up to 4 months. This ability is essential when temperatures often go below freezing.
#16. Spiny Softshell Turtle
- Apalone spinifera
- Females are 7 to 21.25 inches long; males are 5 to 12.25 inches long.
- The carapace is flexible with a rough sandpaper texture, with a single row of spines or cones along the middle of the back. There is also a row of pointed tooth-like appendages on the edge of the carapace.
- Coloring is olive, gray, or brown, with black spots on some individuals.
Look for these reptiles in eastern Colorado in lakes, rivers, and streams with sandy or muddy bottoms and little or no vegetation. I often see them sunning themselves on the banks while kayaking down slow-moving rivers.
Spiny Softshell Turtle Rangemap:
Spiny Softshell Turtles can “breathe” underwater by absorbing oxygen through the skin of their throats. This is a useful adaptation because they spend very little time out of the water, even sunning themselves in shallows or floating on the surface.
This reptile has some other unique adaptations that make it perfectly suited for its environment. Its leathery shell is extremely flat, and it has webbed feet and long claws, which allow it to swim quickly away from predators and bury itself in the muddy bottom.
Its most unique feature is its nose, which is long and snout-like! It can poke its nostrils out of the water and stay completely submerged to protect itself from hungry predators!
#17. Western Box Turtle
- Terrapene ornata
- 4 to 5.75 inches long.
- The carapace is high and rounded, resembling a helmet.
- Coloring is often dark brown or black background with radiating lines or dots.
Western Box Turtles live in open prairies and woodland areas. They prefer loose soil that is easy to burrow into and seek shelter under boards, porches, or other man-made objects.
Western Box Turtle Rangemap:
Western Box Turtles will eat almost anything they can fit in their mouths!
They have even been known to search through cow droppings for beetles!
Female Western Box Turtles have a unique ability when it comes to reproduction. They can mate once with a male turtle and keep the fertilized eggs safe in their bodies for over two years! Then, when the climate and season are most suitable, they lay the eggs.
What types of reptiles in Colorado have you seen?
Let us know in the comments!