● Venomous · Native to California and Baja California

Red diamond rattlesnake

Crotalus ruber Cope, 1892

Data updated October 2026

Red diamond rattlesnake coiled among boulders, showing light-edged diamond blotches on a brick-red body
Fig. 1 — Adult among boulders, showing pale-edged diamonds on a reddish body.
Tail of a red diamond rattlesnake with black and white rings above the rattle
Fig. 2 — Bold black and white rings just above the rattle.

At a glance

A large, reddish rattlesnake of the rocky chaparral, coastal sage scrub and desert slopes of Southern California and Baja California. It is the largest rattlesnake in San Diego County and is often mild-mannered. It is a California Species of Special Concern.

01

Identification

The red diamond rattlesnake is a big, heavy-bodied pit viper with a large triangular head. Its ground color ranges from pink or reddish-tan to reddish-brown or brick red, and a row of diamond-shaped blotches, usually edged in a lighter color, runs down the back. The belly is usually a plain dull yellow. Young are duller than adults, and the red coloring develops as they grow. Unlike most snakes, males tend to be longer than females.

  1. 01Reddish color. Pink, reddish-tan or brick-red, rather than the gray or brown of most rattlesnakes in its range.
  2. 02Ringed tail. Black and white rings of about equal width above the rattle, usually about five black rings. The ring next to the rattle is usually black.
  3. 03Pit viper features. Heat-sensing pits, vertical pupils, keeled scales and a rattle of hollow segments.

The western diamondback rattlesnake also has a black-and-white “coon tail,” and the two can be hard to tell apart where their ranges meet in the deserts of San Diego and Riverside counties. The red diamond is redder overall. Harmless gopher snakes are often mistaken for rattlesnakes but have no rattle.

Commonly confused with

02

Size

01 ft2 ft3 ft4 ft Adult · about 3 ft (91 cm)

Adults typically measure 2 to 4.5 feet (61–137 cm), and large ones approach 6 feet. The longest on record measured 68.3 inches (162 cm). Coastal populations average longer than desert ones. Newborns are about 12 inches (30 cm) long.

03

Range & habitat

Red diamond rattlesnake near a granite boulder in chaparral
Fig. 3 — Rocky outcrops and boulder-strewn chaparral are typical habitat.

In the United States, red diamond rattlesnakes live only in southwestern California, from the Morongo Valley west to the coast, in San Bernardino, Riverside, Orange, Los Angeles, San Diego and Imperial counties. From there the range runs south along the Peninsular Ranges through Baja California, including several islands. They are found below about 5,000 ft in coastal sage scrub, chaparral, arid scrub, oak and pine woodland, rocky grassland and farmland. Rocky outcrops, boulder piles and hillsides are favored, and on desert slopes they reach down into rocky desert flats.

04

Diet & predators

Red diamond rattlesnakes are mammal specialists. They often hunt by ambush beside rodent or lizard trails. Woodrats are the most common prey, followed by kangaroo rats, pocket mice and deer mice, and they also take ground squirrels and rabbits. Lizards and birds are eaten less often. Young snakes eat rodents too, and coastal snakes, which grow larger, take a higher share of big rodents.

Feeds on

  • Woodrats
  • Kangaroo rats and pocket mice
  • Ground squirrels and rabbits
  • Lizards and birds

Preyed on by

  • Natural predators are poorly documented
  • People (persecution)
  • Road traffic
Woodrat sitting on a rock
Prey — woodrats.
Kangaroo rat on sandy ground
Prey — kangaroo rats.

05

Behavior & seasons

Red diamond rattlesnakes are usually rather mild-mannered. Many do not rattle when approached, though an alarmed snake may rear up in a threat display. They are mostly active at dusk and at night during hot weather and by day when temperatures are moderate or in shaded boulder fields. They are ground snakes but will partly climb into shrubs or trees.

They spend cold winter nights in dens in rocky outcrops but do not truly hibernate and may come out on any warm day. In early spring they gather to bask near the dens. The dens are also where males wrestle in combat, where mating takes place and where females give birth. Researchers mapping dens in San Diego County found that the snakes favor particular rock formations, and that disturbance can keep them from returning to a den.

06

Reproduction

Red diamond rattlesnakes give birth to live young. Mating usually takes place in spring, when males also perform wrestling “combat dances” that do not injure either snake. Litters of 3 to 20 young are born from July through September. Females probably start breeding at about three years old.

07

Conservation

The red diamond rattlesnake is not listed under the federal Endangered Species Act or the California Endangered Species Act. California lists it as a Species of Special Concern, and the U.S. Forest Service treats it as a Sensitive species. Development in coastal Southern California has removed and fragmented much of its habitat, and road deaths and killing by people add to the losses. Changes in fire patterns and vegetation linked to climate change may also affect it.

08 — Bite safety

If someone is bitten

Red diamond rattlesnake bites are medically serious, and 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