Colorado’s diverse landscapes are home to several species of rattlesnakes. These venomous snakes are a natural component of the state’s ecosystems, adapted to different environments. Learning about these reptiles can help promote coexistence and safety.
Rattlesnake Species Found in Colorado
Colorado is home to three primary rattlesnake species, each with distinct features. The Prairie Rattlesnake (Crotalus viridis) is the most common and largest, often reaching lengths of 3.5 to 5 feet. Its coloration ranges from light brown to greenish-brown, with darker, often tan or white-bordered, blotches along its back. This species has a triangular head, vertical pupils, heat-sensing pits between its eyes and nostrils, and two narrow, light diagonal stripes on its face.
The Midget Faded Rattlesnake (Crotalus concolor) is smaller, growing to 2 to 2.5 feet. Its name reflects its appearance, with a pinkish, pale brown, yellow-brown, gray, or silvery base color and subtle blotches that fade with maturity. A dark bar may extend behind its eye.
The Western Massasauga (Sistrurus tergeminus) is the smallest of Colorado’s rattlesnakes, measuring between 14 and 36 inches. This species has a light-brown or grayish base color with prominent dark brown blotches, which are wider than they are long. A distinctive dark brown stripe runs from each eye to the corner of the mouth. Its rattle is small, producing a softer, “buzztail” sound.
Where Rattlesnakes Live in Colorado
Rattlesnakes occupy various habitats across Colorado, adapting to different elevations and terrains. The Prairie Rattlesnake is widespread and can be found statewide in areas below 9,000 to 9,500 feet. This species thrives in diverse environments, including open prairies, foothills, riparian corridors, and even within some towns and suburbs. They are frequently encountered near the Colorado River, in the eastern plains, and throughout the foothills of the Rocky Mountains.
The Midget Faded Rattlesnake has a more restricted distribution within Colorado, inhabiting the Green River and Colorado River basins in the western part of the state. This includes counties such as Garfield, Mesa, Delta, Rio Blanco, and San Miguel. These snakes prefer rocky hillsides, cliff-faces, and slopes with numerous crevices and sagebrush thickets at elevations below 7,000 feet.
The Western Massasauga is localized to the sandy terrain of southeastern Colorado, found at elevations below 5,500 feet. Their preferred habitats include dry plains grassland and sandhill areas. They are associated with wetlands or areas with dense grass cover. Rattlesnakes are active from early spring through mid-fall and utilize burrows, rock crevices, or caves for denning during colder months.
Living Alongside Rattlesnakes Safely
Coexisting with rattlesnakes in Colorado involves practicing awareness and taking preventative measures. When outdoors, stay on marked trails and observe where hands and feet are placed. Avoiding stepping over rocks or logs without looking, and refraining from reaching into holes or crevices, can prevent unexpected encounters. Wearing sturdy leather boots provides protection for the lower legs and feet.
Being aware of surroundings is important; avoiding the use of headphones while hiking allows for better detection of potential warnings. Limiting outdoor activity during dusk or evening hours, when rattlesnakes can be more active and visibility is reduced, also contributes to safety. Keeping dogs on a leash helps prevent them from disturbing hidden snakes. For properties, removing brush piles and rock stacks can reduce attractive hiding spots for snakes.
If a rattlesnake is encountered, maintain a safe distance of at least five feet. Moving slowly and calmly away from the snake is the best response. Avoid provoking, attempting to catch, kill, or move the snake, as most bites occur when individuals try to interact with them. A coiled or rattling snake indicates agitation, signaling a need to back away immediately.
In the event of a rattlesnake bite, remaining calm is important. Immediate medical attention should be sought by calling 911 or the Poison Center at 1-800-222-1222. While awaiting professional medical care, any jewelry or tight clothing near the bite area should be removed to accommodate potential swelling. The bitten area should be kept at or below heart level if possible. It is important to avoid traditional but ineffective first aid methods such as cutting the wound, attempting to suck out venom, or applying ice, heat, or a tourniquet.