CDFW strives to increase awareness and understanding of the management and conservation needs of our diverse native snake species throughout the state, including rattlesnakes. They provide important ecosystem benefits and contribute to healthy biodiversity throughout the state. Learn more below!

Conservation and Management

California is home to nearly 50 native snake species, including 7 species of rattlesnake. One species, the red diamond rattlesnake (Crotalus ruber) is a Species of Special Concern.

Snake Fungal Disease (SFD) is a newly emerging disease in snakes and caused by a fungus, (Ophidiomyces ophidiicola). It may only cause mild infection in many snakes, but is known to cause significant mortality in species of special concern in other states, such as the Timber Rattlesnake (Crotalus horridus) not found here.

  • Since 2008, SFD has been detected in more than 30 snake species in North America and Europe. It is present in at least 38 states.
  • In 2019, California confirmed its first two known cases of SFD in a California kingsnake (Lampropeltis californiae) and non-native Florida water snake (Nerodia fasciata pictiventris).
  • How SFD may impact snakes in California is unknown. Report sick or dead snakes to CDFW. For more information, visit the "Disease and Mortality Monitoring" Snake Fungal Disease page.

NOTE: A Commercial Native Rattlesnake Permit is required for every person who possess, propagate, exchange, or transport native rattlesnakes for commercialized venom extraction, or sell, import, or export native rattlesnake venom or products derived from native rattlesnake venom for commercial purposes, or purchase native rattlesnakes from a biological supply house, permitted through Section 651, for the purpose of developing and selling biomedical and therapeutic products.

Science and Research

CDFW continues working to better understand the complex conservation needs of the rattlesnakes and other native reptiles. Research, disease surveillance and monitoring, is vital to applying an adaptive approach to managing their population in California.

Rattlesnake Biology


Rattlesnakes have a distinct triangular-shaped head and a rattle on the end of their tail. The rattle is made of keratin, the same material as nails in mammals. Each time a snake sheds its skin a new “segment” of their rattle is formed. These segments are hollow and create the infamous rattlesnake buzz when clacked against each other at incredible speeds by the snake shaking its tail. Snakes will shed their skin throughout their life and may shed multiple times within a year. A rattlesnake may be seen without a rattle if it has broken off. Young rattlesnakes are born with a small rattle or button and may not properly produce a tail buzz until more segments are developed.

The scales of a rattlesnake can be described as 'keeled' and not smooth. They have a rough and raised texture and are matte in appearance. Their patterns are often mottled in earthy tones which aid in their ability to be well-camouflaged in their habitat.

Rattlesnakes are highly specialized and have evolved the following traits:Rattlesnake ready to strike

  • Small temperature-sensitive “pits” on each side of the head between the eye and nostril, allowing them to find prey in the dark.
  • Forked tongue to detect the scent of prey.
  • Venom produced in glands behind the eyes flow through ducts into hollow fangs.
  • Fangs that fold back against the roof of mouth and pivot forward to inject venom when ready to strike.

Some snakes can mimic the appearance of a rattlesnake, such as the gopher snake (Pituophis catenifer), but are non-venomous and lack a rattle.


Rattlesnakes mostly eat live prey, though some may occasionally feed on dead animals. Rattlesnakes usually hunt in grassy areas, near rodent burrows, and rocky outcrops. Prey are injected with venom to immobilize them, then swallowed whole by the rattlesnake.

  • Adults mostly hunt rodents such as mice, rats, and ground squirrels.
  • Young rattlesnakes mostly hunt young rodents and lizards.

Many other native snakes, such as gopher snakes and kingsnakes, compete with rattlesnakes for resources. Kingsnakes are known to eat rattlesnakes and are resilient against the effects of rattlesnake venom.


Rattlesnake courtship and mating occurs once temperatures heat up with the warmer weather (March to May). In some species of rattlesnake, such as the Western diamondback rattlesnake (Crotalus atrox), males may participate in a combat ritual if competing for a female to mate with. Females often nest in old rodent burrows and rock crevices, and give birth to 1 to 25 live young in the Fall. Baby rattlesnakes receive maternal care for 1-2 weeks before dispersing from the nest.

Rattlesnake Behavior

Rattlesnake Behavior

Rattlesnakes are generally not aggressive and will avoid people. They usually retreat if given safe space to move and not provoked or threatened. Do not attempt to touch or handle snakes – and know what to do in the event of a bite. Rattlesnake coiled on pavement

A startled rattlesnake may NOT rattle before striking defensively. They also may not deliver an envenomed bite - a 'dry bite' may be used as a warning because venom creation and use can be energetically expensive for the snake. However, all bites from a rattlesnake should be treated as a venomous bite until appropriate medical attention is provided.

Rattlesnakes are sensitive to ambient temperature and adjust their behavior accordingly. In warmer weather, you may see one basking in the sun to raise it’s body temperature.

  • In Spring and Summer - Most active at dawn, dusk, and night to avoid overheating.
  • In Fall and Winter - Inactive, and some may go into brumation (a state of dormancy with periods of activity), for several months in rock crevices, rodent burrows, or thick vegetation.

Often multiple rattlesnakes may gather and establish dens during the colder months. These are often in rocky crevices where heat is retained, but may be found underneath homes or man-made structures.

Habitat and Range

Rattlesnakes are widespread and found in diverse habitats throughout California from the coast to inland desert. Rattlesnakes can live in rural and urban areas, on riverbanks, in parks, and at golf courses. They may also turn up around homes and yards in brushy areas and under wood piles. Habitat requirements include rocky, open areas for basking and hiding with a nearby water source, primarily associated with prey activity.

There are seven species of rattlesnake in California:

  • Mohave rattlesnakes (PDF) (Crotalus scutulatus) are found in the desert and foothills of southeastern California.
  • Panamint rattlesnakes (PDF) (C. stephensi) are found in inland desert areas with more northerly distribution across Southern California.
  • Red diamond rattlesnakes (PDF) (C. ruber) are found in Baja California and in southwestern California south of Los Angeles.
  • Sidewinders (PDF) (C. cerastes), sometimes called the horned rattler, are the smallest rattlesnake in California. It is commonly found in desert areas from below sea level up to 6,000 feet.
  • Speckled rattlesnakes (PDF) (C. mitchellii) are found in desert areas from Baja California and much of the Colorado, Mojave, and Sonoran Deserts.
  • Western diamond-backed rattlesnakes (PDF) (C. atrox) are rare in California but can occur in desert areas in the far southeastern part of the state.
  • Western rattlesnakes (PDF) (C. oreganus) are the most widespread rattler in California. It is found statewide from sea level up to 7,000 feet. There are three subspecies, the Northern Pacific rattlesnake (C. o. oreganus) found throughout Central and coastal Northern California, the Southern Pacific rattlesnake (C. o. helleri) found in coastal Southern California, and the Great Basin rattlesnake (C. o. lutosus) found in northern Sierra Nevada.

Potential Conflict and Coexistence

Rattlesnakes typically avoid people. Bites are uncommon, but can occur if a snake feels threatened. Most bites occur between April and October when snakes and humans are most active outdoors. Prevention is key to avoiding unwanted encounters. To learn more, visit the Human-Wildlife Conflict Program page.


  • Stay alert when outdoors.
  • Wear sturdy boots and loose-fitting long pants. DO NOT wear sandals or flip-flops in brushy areas.
  • Stay on well-used trails. Avoid tall grass, weeds, and heavy underbrush.
  • Check rocks, stumps or logs before sitting down.
  • Shake out sleeping bag and tent before use.
  • Let others know where you are going, when you plan to return, and carry a cell phone. Hike with a companion when possible.
  • DO NOT grab “sticks” in water. Rattlesnakes can swim.
  • DO NOT let dogs off leash. Dogs are at increased risk when sniffing the ground near brushy areas.
  • DO NOT try to touch or handle a snake, dead or alive. Dead rattlers may still inject venom shortly after death.

Be Rattlesnake Safe

Rattlesnake bites are uncommon, but can and do still occur. On rare occasions, rattlesnake bites can cause severe injury or death. Prevention is key to human safety.

In the event of a snake bite

  • Stay calm - but act quickly!
  • Remove items which may constrict swelling (e.g., watches, rings, shoes).
  • Transport victim to the nearest medical facility.
    • Do NOT apply a tourniquet.
    • Do NOT pack the bite area in ice.
    • Do NOT cut the wound with a knife or razor.
    • Do NOT use your mouth to suck out the venom.
  • If a pet is bitten - Speak to your veterinarian about canine rattlesnake vaccine options.

For more information, call the California Poison Control System(opens in new tab) at (800) 222-1222.

In the event of an emergency situation, call 9-1-1 and seek medical attention immediately.


Wildlife Health Lab
1701 Nimbus Road Suite D, Rancho Cordova, CA 95670
(916) 358-2790 | WILAB@wildlife.ca.gov