Snakes in Colorado: identification guide and best places to start

1. Where are you most likely to notice snakes in Colorado?

Snakes in Colorado are most often seen in open grasslands, rocky canyons, and near water sources. Prairie rattlesnakes favor the shortgrass prairies east of the Rockies, while bullsnakes and garter snakes hang around river valleys and irrigation ditches. In the foothills, look for them basking on south-facing rocks or crossing trails on warm afternoons. For a deeper dive into Colorado wildlife habitats, check out our Colorado wildlife guide.

2. What seasons and weather patterns increase snake activity?

Spring (April to May) and fall (September to October) are the prime windows for snake spotting in Colorado. Snakes are ectothermic, so they emerge on days when temperatures reach 60-85°F. After a cold night, they often bask on rocks or pavement to warm up. Overcast days with light rain can also push them onto trails to hunt. Avoid the heat of summer midday when they retreat underground.

3. What are simple ID cues to tell Colorado snakes apart?

Start with head shape: rattlesnakes have a distinct triangular head with heat pits between the nostril and eye. Bullsnakes have a more rounded head but flatten it when threatened, mimicking rattlers. Garter snakes are slender with three light stripes running the length of their body. Color patterns also help: prairie rattlesnakes are tan with dark blotches, while bullsnakes are yellowish with darker saddles. Learn more about snake identification on our snake species hub.

See our state animal guide for the next step.

4. Which snake species are common in Colorado and where do they live?

The prairie rattlesnake (Crotalus viridis) is the most widespread venomous snake, covering the eastern plains and foothills up to about 8,000 feet. The bullsnake (Pituophis catenifer) is a large nonvenomous constrictor found in grasslands and farmlands across the state. The common garter snake (Thamnophis sirtalis) prefers wet areas along streams and ponds throughout Colorado. The plains hognose snake (Heterodon nasicus) is a rarer treat on sandy soils of the southeast.

5. How can you stay safe while snake spotting in Colorado?

Watch where you step and never reach into areas you can't see, like rock crevices or tall grass. Wear sturdy boots and long pants on trails. If you encounter a snake, stop and give it space; most bites happen when people try to handle or kill them. Keep dogs on a leash and away from suspicious rustling. In unlikely case of a bite, stay calm, immobilize the area, and get to a hospital immediately.