Colorado snakes: ID chart

31 snakes, 3 venomous (listed first), 11 mildly venomous. Last checked November 3, 2026.

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The 3 venomous snakes come first: Massasauga Rattlesnake, Midget Faded Rattlesnake (Western Rattlesnake), Prairie Rattlesnake. The 11 mildly venomous ones follow. The rest follow from A to Z, each with a photo where we have one and a short note on where it lives in Colorado. The chart prints on letter or A4 paper; on screen, open any name on the Colorado snakes page for photos, range and sources.

Massasauga Rattlesnake

Sistrurus catenatus

Venomous

Southeastern Colorado at elevations below about 5,500 feet.

Midget Faded Rattlesnake (Western Rattlesnake)

Crotalus oreganus concolor

Venomous

Mainly Mesa, Delta, and Garfield Counties.

Prairie Rattlesnake

Crotalus viridis

Venomous

Found throughout most of Colorado, except the high mountains, reaching an upper elevational limit of …

Black-necked Garter Snake

Thamnophis cyrtopsis

Mildly venomous

Known to occur as far north as the Arkansas River valley in southeastern Colorado, in John Brown Canyon in …

Chihuahuan Nightsnake

Hypsiglena jani

Mildly venomous

Colorado Distribution: Southeastern Colorado, mostly south of the Arkansas River, and west-central Colorado …

Common Garter Snake

Thamnophis sirtalis

Mildly venomous

Northeastern Colorado along the South Platte River and its tributaries at elevations below 6,000 feet and …

Desert Nightsnake

Hypsiglena chlorophaea

Mildly venomous

Colorado Distribution: Southeastern Colorado, mostly south of the Arkansas River, and west-central Colorado …

Eastern Hognose Snake

Heterodon platirhinos

Mildly venomous

This species was recently found in extreme Eastern Colorado near Holly, CO.

No confirmed photo of Plains Black-Headed Snake

Plains Black-Headed Snake

Tantilla nigriceps

Mildly venomous

Known from southeastern Colorado, the Republican River drainage in northeastern Colorado, and the eastern …

Plains Garter Snake

Thamnophis radix

Mildly venomous

Throughout the Great Plains region of Colorado, primarily at elevations below 6,000 feet, but individuals …

Ring-Necked Snake

Diadophis punctatus

Mildly venomous

Southeastern Colorado south of the Arkansas River, at elevations below 6,000 feet …

No confirmed photo of Smith's Black-Headed Snake

Smith's Black-Headed Snake

Tantilla hobartsmithi

Mildly venomous

West-central Colorado at elevations of about 4,500-6,500 feet …

Terrestrial Garter Snake

Thamnophis elegans

Mildly venomous

Throughout most of Colorado, excluding most of the plains region in the northeastern quarter of the state …

Western Hognose Snake

Heterodon nasicus

Mildly venomous

Throughout most of eastern Colorado at elevations below 6,000 feet. Fairly common …

California Kingsnake

Lampropeltis californiae

Non-venomous

Known from a few locations in southeastern Colorado (north to the vicinity of the Arkansas River) and a few …

Coachwhip

Coluber flagellum

Non-venomous

Southeastern Colorado, generally at elevations below 6,000 fe et but locally up to 7,700 feet, and the …

Glossy Snake

Arizona elegans

Non-venomous

Plains of eastern Colorado, and Montezuma County in extreme southwestern Colorado.

Gophersnake/Bullsnake

Pituophis catenifer

Non-venomous

Throughout most of Colorado at elevations below about 8,500 feet, mostly below 7,000 feet. Common.

Great Plains Ratsnake

Pantherophis emoryi

Non-venomous

Southeastern and west-central Colorado below 6,000 feet; likely also in extreme northwestern Colorado …

Lined Snake

Tropidoclonion lineatum

Non-venomous

Portions of eastern Colorado below 6,000 feet; definitely most abundant in southeastern Colorado …

Long-Nosed Snake

Rhinocheilus lecontei

Non-venomous

Southeastern Colorado below 5,000 feet.

Milksnake

Lampropeltis triangulum

Non-venomous

Throughout the state, below 8,000 feet.

North American Racer

Coluber constrictor

Non-venomous

Eastern Colorado (widespread and common) and valleys and canyons of western Colorado (more localized and less …

Northern Watersnake

Nerodia sipedon

Non-venomous

Along streams in the plains region of eastern Colorado at elevations below about 5,500 feet. Fairly common.

Rubber Boa

Charina bottae

Not stated

Possible Colorado Distribution: Reported without adequate documentation from Dinosaur National Monument …

Smooth Greensnake

Opheodrys (Liochlorophis) vernalis

Non-venomous

Patchy distribution around the margins of the mountains, generally at elevations of 5,500-9,000 feet …

Speckled Kingsnake

Non-venomous

Striped Whipsnake

Coluber taeniatus

Non-venomous

Throughout western Colorado at elevations up to about 7,000 feet in the north and 8,100 feet in the south …

Texas Threadsnake

Rena dulcis

Non-venomous

Known from a few locations in southeastern Colorado. Secretive, burrowing species; abundance uncertain.

Western Ground Snake

Sonora semiannulata

Non-venomous

Southeastern Colorado south of the Arkansas River, at elevations below 5,500 feet …

Western Ribbonsnake

Non-venomous

A picture cannot confirm what an animal is or that it is safe. Never handle a wild animal. Sources: Species Profile List, filtered to Type = Reptile (Colorado Parks and Wildlife); Species profile: Terrestrial Garter Snake (Colorado Parks and Wildlife); Species profile: Black-necked Garter Snake (Colorado Parks and Wildlife); Species profile: California Kingsnake (Colorado Parks and Wildlife); Species profile: Chihuahuan Nightsnake and Desert Nightsnake (Colorado Parks and Wildlife); Quick Key to Amphibians and Reptiles of Colorado (Colorado Parks and Wildlife); and others listed on the web page. stateswildlife.com/colorado/snakes/