Believe it or not, you can find THREE types of rattlesnakes in Colorado!
But please don’t live in fear, thinking that you are going to be bitten. In general, rattlesnakes try to avoid any contact or interaction with people. The whole reason they have a rattle is to warn you to stay away! As long as you leave them alone, you shouldn’t have any trouble.
*If you come across any of these species, PLEASE DO NOT DISTURB! Rattlesnakes are dangerous animals and should be left alone. The more you agitate them, the more likely you could get bitten. DO NOT RELY ON THIS ARTICLE to correctly identify a rattlesnake that has recently bitten you. If you have recently been bitten, GO DIRECTLY to the nearest hospital to get help and determine if the snake is venomous.*
RELATED: The 20 Types of SNAKES Found in Colorado! (ID Guide)
#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, and a tail rattle.
These rattlesnakes can be found in Colorado in open prairies, grasslands, semi-desert shrublands, and forested environments. They can even be found at elevations up to 9500 feet (2900 m)!
The Prairie Rattlesnake hibernates during the winter, often in communal dens. These dens are typically rock crevices, caves, or old mammal burrows. Individual snakes will 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 will freeze, using 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. Their biggest threats are pressures from habitat fragmentation and hunting.
#2. Western Massasauga
- Sistrurus tergeminus
- Adults range from 14 to 36 inches in length.
- Coloration is gray to light brown with dark brown blotches on the back.
- Thick body, large triangular head, heat-sensing pits between the eyes and nostrils, elliptical pupils, and rattle on the tail.
The Western Massasauga is one of the smallest rattlesnakes in the country! They primarily inhabit grassland habitats but can also be found in open sagebrush prairie, rocky hillsides, prairie hillsides, open wetlands, and grassy wetlands.
Western Massasauga Range Map
This rattlesnake is secretive and is not often seen in Colorado.
When detected, they often freeze rather than make a rattle. However, when they do rattle, Western Massasaugas make a distinctive sound. Their rattle is significantly higher pitched than larger rattlesnakes and has earned this small snake the nickname “buzz tail.”
Though their venom is highly potent, the small quantity they deliver makes their bites much less likely to be fatal in humans than some larger rattlesnakes. However, you still need to respect them as their venom is hemotoxic and will cause localized swelling, extreme pain, and necrosis. Medical attention should be sought immediately if bitten!
#3. Western Rattlesnake
- Crotalus oreganus
- Adult size varies widely over their range, with the largest individuals being 6 feet long.
- Coloration varies greatly and can be dark brown, yellowish, dark gray, or olive-brown.
- Triangular head. A dark stripe with white borders that runs from the eye towards the jaw.
Also known as the Northern Pacific Rattle Snake, this species occupies a wide range of habitats. They can be found in mountainous areas, woodlands, and grasslands. They often occur in close proximity to humans.
Western Rattlesnakes have excellent camouflage and unique coloring, as these snakes show considerable variation. When they’re young, they have a distinct color pattern, but it fades over time as the snakes mature.
These snakes may be active during the day or night and are often curled, waiting to ambush various 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 up to 25 babies!
Do you need additional help identifying a rattlesnake?
I recommend purchasing a Peterson Field Guide to the Reptiles and Amphibians of North America. These books have lots of helpful information, including pictures and range maps.
Which of these rattlesnakes have YOU seen before in Colorado?
Leave a comment below!