State herp calendar
Reptiles and Amphibians of Colorado
Colorado is high mountains in the west and plains in the east. Western Terrestrial Garter Snakes are the most-reported herp. Woodhouse's Toads and Prairie Lizards are common on the plains. June is the busiest month. The Prairie Rattlesnake is the only venomous snake on the list.
45 species5 ecoregions1 venomous
Search entire stateSpecies out across Colorado, by group and month
| Group | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Snakes | 5 | 15 | 17 | 17 | 16 | 16 | 14 | 11 | 5 | 1 | ||
| Lizards | 2 | 6 | 12 | 13 | 13 | 13 | 13 | 12 | 7 | 3 | ||
| Turtles | 2 | 3 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 3 | ||
| Frogs and Toads | 1 | 1 | 3 | 5 | 9 | 9 | 9 | 9 | 8 | 5 | 2 | 1 |
| Salamanders | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
Numbers = species active that month (at peak or just starting / winding down).
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Hi, I'm Nick. I built Herp Calendar on my own and I keep it free, with no ads. If it has helped you find a herp this season, a small tip goes straight into the hosting and the data work. Only if you can spare it. Either way, I'm glad you're here.
Pick your ecoregion
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Tap a region to see what's out
Ecoregions of Colorado
Seasons shift a lot between Colorado's ecoregions. Pick the one nearest you for a 12-month calendar of what's out.
Southern Rockies
17 speciesHigh mountains where garter snakes and tiger salamanders make the most of summer.
View calendar →Southwestern Tablelands
36 speciesCanyons and breaks with prairie lizards, collared lizards and rattlesnakes.
View calendar →High Plains
24 speciesShortgrass prairie and playa lakes with plains toads and prairie rattlesnakes.
View calendar →Colorado Plateau
34 speciesRed-rock canyon country with fence lizards, collared lizards and gopher snakes.
View calendar →Middle Rockies and Wyoming Basin
10 speciesHigh, cold country with a short season and just a handful of herps.
View calendar →Venomous here: Prairie Rattlesnake. Don't handle any snake you can't identify.
About Colorado
When are reptiles and amphibians most active in Colorado?
June is the busiest month in Colorado, with 39 species at peak activity. At least half of the area's species are active from April through October.
What reptiles and amphibians live in Colorado?
45 species have enough iNaturalist records to show here: 17 snakes, 13 lizards, 9 frogs and toads, 5 turtles, and 1 salamander. The most-reported are the Western Terrestrial Garter Snake, Woodhouse's Toad, and Gopher Snake.
Are there venomous snakes in Colorado?
Yes. The Prairie Rattlesnake lives here. Don't handle them.
Which reptiles and amphibians in Colorado are introduced?
The Pond Slider is not native here.
Where does this data come from?
Activity calendars are built from iNaturalist research-grade observations (downloaded through GBIF, September 2026), corrected for how many people are out observing each month. Rare and protected species are left off on purpose.