Snakes in Colorado
Colorado has 26 snake species on record, each with at least 10 GBIF records in the state, and 3,484 licensed records in all. The most recorded are the prairie rattlesnake, the western terrestrial garter snake and the gopher snake. Three of them are venomous.
Rattlesnakes in Colorado
Rattlesnakes dominate the snake record of Colorado: three species and 40% of all records. The most recorded is the prairie rattlesnake (1,328), ahead of the western rattlesnake (47).
Observation records of the prairie rattlesnake in Colorado run mostly May through September, peaking in May; most licensed records come from Weld County, Moffat County and Baca County. Most licensed records of the western rattlesnake in Colorado come from Rio Blanco County, Moffat County and Mesa County.
Water snakes and swamp snakes in Colorado
One species of this group is listed for Colorado: the northern water snake, with 42 records (1% of the state's snake records).
Most licensed records of the northern water snake in Colorado come from Yuma County, Boulder County and Denver County.
Garter snakes and ribbon snakes in Colorado
Garter snakes and ribbon snakes dominate the snake record of Colorado: four species and 35% of all records. The most recorded is the western terrestrial garter snake (835), ahead of the plains garter snake (262).
Observation records of the western terrestrial garter snake in Colorado run mostly May through October, peaking in July; most licensed records come from Gunnison County, Larimer County and Boulder County. Observation records of the plains garter snake in Colorado run mostly May through October, peaking in June; most licensed records come from Boulder County, Larimer County and Adams County. Most licensed records of the common garter snake in Colorado come from Mesa County, Boulder County and Adams County.
Rat snakes and corn snakes in Colorado
One species of this group is listed for Colorado: the Great Plains rat snake, with 5 records (0.1% of the state's snake records).
Kingsnakes and milksnakes in Colorado
Kingsnakes and milksnakes are a small part of the snake record here: three species with 1% of records between them. The most recorded is the central plains milksnake (29), ahead of the eastern milksnake (8).
Racers, whipsnakes and indigo snakes in Colorado
Racers, whipsnakes and indigo snakes: three species are listed for Colorado, with 200 records (6% of the state's snake records). The most recorded is the eastern racer (123), ahead of the coachwhip (58).
Observation records of the eastern racer in Colorado run mostly May through September, peaking in May; most licensed records come from Boulder County, Larimer County and Jefferson County. Most licensed records of the coachwhip in Colorado come from Otero County, Pueblo County and El Paso County.
Gopher snakes, bullsnakes and pine snakes in Colorado
One species of this group is listed for Colorado: the gopher snake, with 365 records (10% of the state's snake records).
Observation records of the gopher snake in Colorado run mostly April through September, peaking in May; most licensed records come from Boulder County, Larimer County and El Paso County.
Hognose snakes in Colorado
One species of this group is listed for Colorado: the plains hog-nosed snake, with 45 records (1% of the state's snake records).
Most licensed records of the plains hog-nosed snake in Colorado come from Weld County, El Paso County and Pueblo County.
Green snakes in Colorado
One species of this group is listed for Colorado: the smooth green snake, with 21 records (0.6% of the state's snake records).
Small woodland and burrowing snakes in Colorado
Small woodland and burrowing snakes: eight species are listed for Colorado, with 123 records (4% of the state's snake records). The most recorded is the western ground snake (36), ahead of the glossy snake (33).
Most licensed records of the western ground snake in Colorado come from Otero County, Las Animas County and Baca County. Most licensed records of the glossy snake in Colorado come from Pueblo County, Montezuma County and Otero County.
Where in Colorado are snakes recorded most?
Weld County dominates: 26% of the state's licensed snake records come from it alone, and the top five counties hold 54%. 63 of Colorado's 64 counties have at least one licensed snake record.
| # | County | Records | Share |
|---|---|---|---|
| 1 | Weld County | 916 | 26.3% |
| 2 | Boulder County | 336 | 9.6% |
| 3 | Larimer County | 278 | 8.0% |
| 4 | El Paso County | 187 | 5.4% |
| 5 | Gunnison County | 150 | 4.3% |
| 6 | Jefferson County | 129 | 3.7% |
| 7 | Otero County | 118 | 3.4% |
| 8 | Moffat County | 115 | 3.3% |
| 9 | Pueblo County | 113 | 3.2% |
| 10 | Baca County | 102 | 2.9% |
| 11 | Mesa County | 93 | 2.7% |
| 12 | Adams County | 72 | 2.1% |
When do snakes come out in Colorado?
Observation records of snakes in Colorado run mostly April through September, peaking in May with 22% of them. December through February together hold under 2% of the records, so snakes in Colorado are rarely recorded in winter. The sharpest rise comes from April to May.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0% | 0% | 1% | 6% | 22% | 19% | 19% | 16% | 12% | 5% | 0% | 0% |
Snakes: Colorado compared with its neighbors
Colorado ranks 23rd of 50 states by the number of snake species listed; Texas leads with 86 species.
Of the seven states bordering Colorado, Arizona, New Mexico, Oklahoma, Kansas, Nebraska and Utah list more snake species (Colorado: 26 species; Arizona 60, New Mexico 56, Oklahoma 50, Kansas 44, Nebraska 31, Utah 28, Wyoming 11).
What snakes are in Colorado? All 26 species
Ranked by licensed records in Colorado. Species with a profile page are linked.
| # | Species | Family | Records | Share |
|---|---|---|---|---|
| 1 | Prairie rattlesnake venomous Crotalus viridis | Viperidae | 1,328 | 38.1% |
| 2 | Western terrestrial garter snake Thamnophis elegans | Colubridae | 835 | 24.0% |
| 3 | Gopher snake Pituophis catenifer | Colubridae | 365 | 10.5% |
| 4 | Plains garter snake Thamnophis radix | Colubridae | 262 | 7.5% |
| 5 | Eastern racer Coluber constrictor | Colubridae | 123 | 3.5% |
| 6 | Common garter snake Thamnophis sirtalis | Colubridae | 111 | 3.2% |
| 7 | Coachwhip Masticophis flagellum | Colubridae | 58 | 1.7% |
| 8 | Western rattlesnake venomous Crotalus oreganus | Viperidae | 47 | 1.3% |
| 9 | Plains hog-nosed snake Heterodon nasicus | Colubridae | 45 | 1.3% |
| 10 | Northern water snake Nerodia sipedon | Colubridae | 42 | 1.2% |
| 11 | Western ground snake Sonora semiannulata | Colubridae | 36 | 1.0% |
| 12 | Glossy snake Arizona elegans | Colubridae | 33 | 0.9% |
| 13 | Central plains milksnake Lampropeltis gentilis | Colubridae | 29 | 0.8% |
| 14 | Lined snake Tropidoclonion lineatum | Colubridae | 21 | 0.6% |
| 15 | Smooth green snake Opheodrys vernalis | Colubridae | 21 | 0.6% |
| 16 | Striped whipsnake Masticophis taeniatus | Colubridae | 19 | 0.5% |
| 17 | Western massasauga venomous Sistrurus tergeminus | Viperidae | 17 | 0.5% |
| 18 | Plains black-headed snake Tantilla nigriceps | Colubridae | 12 | 0.3% |
| 19 | Ring-necked snake Diadophis punctatus | Colubridae | 10 | 0.3% |
| 20 | Eastern milksnake Lampropeltis triangulum | Colubridae | 8 | 0.2% |
| 21 | Great Plains ground snake Sonora episcopa | Colubridae | 7 | 0.2% |
| 22 | Great Plains rat snake Pantherophis emoryi | Colubridae | 5 | 0.1% |
| 23 | Long-nosed snake Rhinocheilus lecontei | Colubridae | 3 | 0.1% |
| 24 | Blackneck garter snake Thamnophis cyrtopsis | Colubridae | 2 | 0.1% |
| 25 | Speckled kingsnake Lampropeltis holbrooki | Colubridae | 2 | 0.1% |
| 26 | Chihuahuan night snake Hypsiglena jani | Colubridae | 1 | 0.0% |
Also recorded in Colorado, fewer than 10 times
Beyond the main list, six snake species are known from Colorado by only 3 to 9 records each. Some are genuine rarities at the edge of their range; others may be strays, released pets or old misidentifications, so treat them as unconfirmed.
Related pages
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.