Crotalus viridisRafinesque, 1818

Viridis

Photograph by Guillermo Roque, CC BY, via iNaturalist

A ground-dwelling, nocturnal, meat-eating snake from the Nearctic region, reaching 165 cm nose to tail.

Also called Green Prairie Rattlesnake, Prairie Rattlesnake, Western Rattlesnake.

Reptilia › Squamata › Viperidae › Crotalus

Grows to: 1650mm; greatest recorded
Eats: Carnivorous
Active: Nocturnal
Lives up to: 24.1years

Body length across Viperidae

Longer than 91% of all vipers anyone has measured.

91% of 362 species are smaller9% larger

280 mmthe whole family, smallest to largest3,900 mm

The bar is the rank itself: its length is the share of the family this animal exceeds. The chart below is the family’s real spread, on a logarithmic scale because body length here runs from 280 to 3,900 mm. The solid rule is this animal. Every bar is a count of real species, and nothing on this figure is estimated.

What is known

39 sourced facts, each taken from a named scientific dataset. How to read these.

Cited from a dataset unless a row is marked otherwise.

Standing in the world

Still living: Extant
Conservation status: Least Concern
Status assessed · the year the Red List last looked: 2007
Population trend: Stable

The animal itself

Limbs: None
Venomous: Yes
Fangs: At the front of the mouth
Longest recorded life: 24.1years
Preferred body temperature · chosen in a laboratory gradientmeasured: 28.3°C
Body temperature when active · measured in the wild: 28.9°C84 °F
Body temp in the wild · mean, when active: 28.9°C

Size

Length snout to vent · greatest recorded: 678.7mm2 ft 3 in
Length nose to tail · greatest recorded: 1650mm5 ft 5 in
Body mass · greatestcomputed: 2238.1g4.9 lb
Body mass · a typical adult: 1647g3.6 lb
Body mass at hatchingmeasured: 9.8g0.35 oz

How it lives

Diet: Carnivorous
How it hunts: Mixed
Active: Nocturnal
Where it lives: Terrestrial
Habitat: Desert, Forest, Grassland, Rocky, Shrubland
Biome: Temperate Grasslands, Savannas & Shrublands
Region: Nearctic
Mainland or island: Mainland
Highest it lives · above sea level: 4000m
Range size: 1,922,554km²

Breeding

Reproduction: Viviparous
Average clutch: 9.8eggs
Eggs or young per clutch: 9–10eggs
Mean clutch: 9.8eggs
Clutches in a year: 0.5per year
First breeds at: 54months

Naming and history

Suborder: Serpentes
Infraorder: Alethinophidia
Subspecies: No
Described by: Rafinesque
Moved to another genus · since it was first described: Yes
Described in: 1818
Type locality: USA

Keeping one

5 ft 5 in × 2 ft 8 in × 4 ft 1 in(165 × 83 × 124 cm)

Minimum length × width × height, for one animal. Bigger is always better.

The standard sizes snakes as a fraction of total length: 1 × 0.5 × 0.75.

Mindestanforderungen an die Haltung von Reptilien (Sachverständigengutachten), German Federal Ministry for Nutrition, Agriculture and Forestry, Animal Welfare Division, 10 January 1997. The standard states these floor areas are recommendations rather than binding limits.

From this animal’s own total length of 5 ft 5 in (1650 mm), at 1 × 0.5 × 0.75 times it, following the German federal welfare standard — how this is worked out.

In a laboratory thermal gradient this species settled at 83 °F (28.3 °C).

Preferred body temperature, recorded in a laboratory gradient where the animal could choose freely. A measurement of the animal, not a setting for a thermostat.

Feeding

A prey item should be between the same width as the widest part of the snake's body and about 1.5 times that width.

Widely used across snake husbandry references. An alternative formulation gives prey at 10-15% of the snake's body mass. This is established practice, not a measurement.

186kJ per day

Worked out for an animal of 2,238 g, the heaviest recorded for Viridis — so it is the top of the range, not a figure for a particular animal. Weigh yours and the number will be lower.

An upper estimate, not a feeding target, and not veterinary advice. The equation covers only what an animal burns staying alive, so a growing, gravid or recovering animal needs more — and it was measured on wild animals, which move far more than one in an enclosure. Body condition and a vet who knows the species are what a feeding decision should rest on. Where this comes from.

What nobody knows

These are not gaps in our research. No scientific dataset records them for this species — and saying so is information you cannot get from a reference that simply leaves a field out.

— Length snout to vent · adult female mean
— Length snout to vent · adult male mean
— Length snout to vent · adult mean
— Female length · mean, nose to tail
— Length nose to tail · adult male mean
— Length nose to tail · adult mean
— Largest female · snout to vent
— Largest male · snout to vent
— Largest female · shell length
— Largest male · shell length
— Hatchling length · snout to vent
— Hatchling length · nose to tail
— Largest juvenile · snout to vent
— Largest juvenile · shell length
— Egg length
— Egg width
— Body mass · adult female, mean
— Eats arthropods
— Eats vertebrates
— Eats plant matter
— How the young develop
— Gestation or incubation
— Clutches a year · fewest
— Clutches a year · most
— Hatchling length · smallest recorded
— Hatchling length · largest recorded
— Age at first breeding · female
— Mature from · youngest recorded
— Mature by · oldest recorded
— Size at maturity · smallest recorded
— Size at maturity · largest recorded
— Colour on the back
— Pattern on the back
— Pupil
— Sex decided by
— Red List criteria
— Active season · shortest recorded
— Active season · longest recorded
— Density · lowest recorded
— Density · highest recorded
— Home range · largest recorded
— Active in
— Lowest it lives · above sea level

Others in Viperidae

Take this data

Everything on this page is available as data under CC BY 4.0 — use it freely, credit it, no permission needed.

This species as JSON · the whole dataset

Cite this page

The Reptile & Amphibian Encyclopedia (2026). Crotalus viridis. Retrieved 2026-09-08, from https://www.allanglescreatures.com/species/crotalus-viridis

@misc{crotalus_viridis_2026,
  title  = {Crotalus viridis},
  author = {{The Reptile & Amphibian Encyclopedia}},
  year   = {2026},
  url    = {https://www.allanglescreatures.com/species/crotalus-viridis}
}

Sources

Meiri, S. (2024). SquamBase — a database of squamate (Reptilia: Squamata) traits. Global Ecology and Biogeography. Public domain (CC0).
Oskyrko, O. et al. (2024). ReptTraits: a comprehensive dataset of ecological traits in reptiles. Scientific Data. Used under CC BY 4.0.
Catalogue of Life (dataset 3LR), used under CC BY.
AnAge, Human Ageing Genomic Resources (de Magalhães et al.), used under CC BY 3.0.