● Venomous · Native to the United States

Prairie rattlesnake

Crotalus viridis (Rafinesque, 1818)

Also called western rattlesnake, green prairie rattlesnake
Data updated October 2026

Prairie rattlesnake coiled in short prairie grass, showing dark brown blotches on a greenish-tan body
Fig. 1 — Adult coiled in shortgrass prairie, showing the row of dark, pale-edged blotches down the back.
Close view of a prairie rattlesnake's triangular head with two pale lines on the side of the face
Fig. 2 — Two thin pale lines cross each side of the face.

At a glance

The common rattlesnake of the Great Plains and Rocky Mountain foothills, from west Texas to southern Canada. It hunts rodents around prairie dog towns and rock outcrops and gathers in shared dens for winter. Every bite needs emergency care.

01

Identification

A heavy-bodied rattlesnake with a row of large brown or blackish blotches down the back, each edged in white or cream. Toward the tail the blotches turn into rings. Background color varies a lot: greenish, olive, straw-yellow, gray-brown, tan or even pinkish. The belly is pale yellow to white with no markings. Like all pit vipers it has a heat-sensing pit between each eye and nostril and vertical pupils, and the tail ends in a rattle.

  1. 01Pale-edged blotches. Dark blotches outlined in white run down the back, with smaller blotches along the sides. They become bands near the tail.
  2. 02Two face lines. Two thin white or cream lines run across each side of the face.
  3. 03A true rattle. Across much of the northern Plains it is the only snake with a rattle. A new segment is added at each shed, so rattle length does not tell you its age.

Commonly confused with

02

Size

01 ft2 ft3 ft4 ft Typical adult · about 40 in (102 cm)

Most adults are about 35 to 45 inches (89–114 cm) long, though size varies by region. Snakes on the northern Plains can top 5 feet, while the smaller Hopi rattlesnake of northeastern Arizona usually stays under about 28 inches. Newborns have only a single “button” and cannot rattle until after their first shed.

03

Range & habitat

Rocky outcrop on a grassy prairie slope, typical prairie rattlesnake habitat
Fig. 3 — Sunny, rocky slopes in open grassland are classic prairie rattlesnake country.

Prairie rattlesnakes range across the western Great Plains and Rocky Mountain region, from southern Alberta and Saskatchewan south to western Texas and into northern Mexico. In the US they occur from Montana and the Dakotas south through Wyoming, Nebraska, Colorado and Kansas to western Oklahoma, New Mexico and west and central Texas, with an isolated population in the Loess Hills of western Iowa. They live in shortgrass and mixed-grass prairie, sagebrush and desert scrub, badlands and river breaks, and the lower edges of pine forest. Rock outcrops, south-facing slopes and prairie dog towns are favorite spots.

State guides: Texas · Oklahoma

04

Diet & predators

Prairie rattlesnakes are mostly ambush hunters. They wait beside rodent runs and burrow entrances, strike, then follow the scent trail of the bitten animal. Mice and ground squirrels make up most of the diet, along with young rabbits, ground-nesting birds and lizards. First-year young face heavy losses to predators.

Feeds on

  • Deer mice and other mice
  • Ground squirrels and young prairie dogs
  • Young rabbits
  • Small birds and lizards

Preyed on by

  • Hawks and eagles
  • Coyotes and other carnivores
  • Other snakes (young rattlesnakes)
Deer mouse on the ground
Prey — mice.
Red-tailed hawk perched on a post
Predator — hawks.

05

Behavior & seasons

Its blotched pattern blends into grass and rock, so a still snake is easy to miss. When disturbed it usually rattles a warning and may strike if pressed. Most bites happen when people handle or provoke these snakes. In spring and on mild days it is active by day; in the heat of summer it shifts to dusk and night.

Prairie rattlesnakes return to the same winter dens year after year, often in rock crevices or old prairie dog burrows. In the north a single den may hold well over a hundred snakes. In summer some travel several miles from the den to hunt, then head back in fall.

06

Reproduction

Prairie rattlesnakes give birth to live young. Mating mostly takes place in mid to late summer, and in some places in spring after the snakes leave their dens. Rival males wrestle, rising up and twining together to push each other down. Young are born from late August to October, usually somewhere between 4 and 25 per litter. In the north females often breed only every second year, and pregnant females may gather at shared basking sites. Mothers stay near their newborns for a few days.

07

Conservation

The prairie rattlesnake is not listed under the US Endangered Species Act and remains common in much of the West. At the edge of its range it is rare: it is listed as endangered in Iowa, and Montana counts it as a Species of Greatest Conservation Need. Loss of grassland to farming, destruction of den sites, roads and persecution are the main threats.

08 — Bite safety

If someone is bitten

Prairie rattlesnake bites are a medical emergency. Every bite needs medical care. Call 911 or go to the nearest emergency department. For guidance, call Poison Control at 1-800-222-1222. If a pet is bitten, take it to a veterinarian right away.

This page does not give first-aid or treatment instructions. Read our safety disclaimer.

Keep reading

Sources

Data updated October 2026 · How we build these pages