Colorado is home to a variety of wildlife, including a small number of venomous snake species. While these reptiles are present across much of the state, encounters remain infrequent for individuals who take appropriate precautions. Understanding where these animals live and how to identify them is the most effective way to ensure safety while recreating outdoors. This information informs residents and visitors about the specific risks and proper protocol for interacting with Colorado’s native pit vipers.
Identifying Colorado’s Venomous Species
All venomous snakes in Colorado belong to the pit viper subfamily, which includes all native rattlesnakes. These species share physical characteristics that distinguish them from non-venomous species. Pit vipers possess a broad, triangular head shape, which is noticeably wider than their narrow neck. They also have vertically elliptical pupils and are named for the pair of heat-sensing pits located between their eyes and nostrils, which they use to detect warm-blooded prey.
The most common and widespread species is the Prairie Rattlesnake (Crotalus viridis), a robust snake that can reach over four feet in length. A localized species in western Colorado is the Midget Faded Rattlesnake (Crotalus concolor), which is generally smaller but possesses venom with a higher concentration of potent neurotoxins. The third species is the Western Massasauga (Sistrurus tergeminus), a small, thick-bodied rattlesnake found in the southeastern part of the state. The Massasauga is unique because its head is covered in large plate-like scales rather than the numerous small scales found on the heads of the larger rattlesnake species.
Understanding Geographic Distribution
The distribution of Colorado’s venomous snakes depends on elevation and habitat type. The Prairie Rattlesnake is the most adaptable and occupies the widest range, spanning the Eastern Plains, foothills, and river bottoms across the state. This species can be found in habitats up to an elevation of approximately 9,500 feet. Above this elevation, venomous snakes are generally absent due to unsuitable habitat and cooler temperatures.
The Midget Faded Rattlesnake has a restricted range, found only in the canyon and river basins of far western Colorado. Its habitat is concentrated in the Green and Colorado River systems, typically below 7,000 feet in elevation. These snakes are often found near rocky outcroppings and sandstone cliffs where they can easily camouflage. The Western Massasauga is also geographically restricted, limited primarily to the dry grasslands and sandhill areas of the southeastern plains. This species is generally found at elevations below 5,500 feet.
Essential Safety and Encounter Protocol
Encountering a venomous snake requires calm, deliberate action to ensure safety. The best defense is proactive avoidance, which includes staying on well-defined trails and watching where hands and feet are placed, especially around rocks, logs, and tall brush. Using a walking stick to gently tap the ground ahead can alert a coiled snake to your presence, giving it a chance to move away. Never attempt to handle a snake, even if it appears dead, as muscle reflexes can still trigger a bite.
If a bite occurs, remain calm and immediately call 911 or emergency services. Panic increases heart rate, which accelerates the spread of venom through the body. Remove any jewelry or tight clothing from the affected limb before swelling begins. Immobilize the bitten area, keeping it at or slightly below the level of the heart.
Do not apply ice, cut the wound, attempt to suck out the venom, or use a tourniquet. These actions can cause further tissue damage or increase venom circulation. The only effective treatment for envenomation is antivenom, which must be administered by medical professionals in a hospital setting.