Rattlesnake eating a gopher
Rattlesnake eating a gopher.

Yosemite National Park is home to only one rattlesnake–the Northern Pacific rattlesnake (Crotalus oreganus). Rattlesnakes, an important component of the park’s ecosystem, help control rodent populations. Predators, whether bobcats or coyotes or snakes, control prey that can grow out of balance otherwise.

Rattlesnakes are part of the natural environment of Yosemite. The primary prey of adult rattlesnakes is California ground squirrels, with smaller snakes eating smaller mammals. Their interaction with other species makes them an important component of the park's ecosystem. Rattlesnakes are found in a variety of habitat types up to about 9,000 feet elevation, usually near cover, such as rocks, logs, and woodpiles.

Rattlesnake takes a defensive pose
Beware of reaching in rock crevices or under rocks where rattlesnakes reside.

Gary M. Stolz/U.S. Fish and Wildlife

Basic Biology

  • Physical description: Brownish gray, has a triangular head, narrow neck, and vertical pupils
  • Size: 2 to 4 four feet long
  • Diet: Primarily California ground squirrels
  • Habitat: Under cover, such as rocks, logs and woodpiles up to 9,000 feet in elevation
  • Rattle frequency: Rarely rattle, even around predators; instead, remain still to avoid being seen
  • Rattle rate: 20-100 times per second, depending on temperature (warm snakes rattle faster)
  • Rattle growth: Add a “rattle” made of hardened keratin (like fingernails) each time skin is shed
  • Tongue behavior: Increase the rate of tongue flicking to obtain scent information

Because rattlesnakes are venomous, visitors should educate themselves on identification and precautions. The good news: deaths are very uncommon, and, in fact, no one has ever died from a bite in Yosemite (except for one questionable account in 1931). In addition, 30 percent of adult rattlesnake bites have no venom injected.

How to Avoid Rattlesnakes

  • Walk or hike in areas where the ground is clear, so you can see where you step or reach with your hands.
  • If you think you hear a rattlesnake, stand still until you’ve located the snake, then move away.
  • Don’t rely on hearing a rattle – baby rattlesnakes don’t have a rattle but are just as venomous and adult snakes’ rattles can break off.
  • Wear protective clothing such as long heavy pants and high boots.
  • Wear gloves when using your hands to move rocks or brush.
  • Watch where you step, and never put your hands in areas where you cannot see.
  • Ledges, cracks or holes are common areas where rattlesnakes can be found resting.

If you Encounter a Rattlesnake

  • Keep your distance--rattlesnakes can strike only a distance equal to half their own length.
  • Watch where you step or reach with your hands.
  • Stand still if you think you hear a snake, until you’ve located the snake; then move away.
  • Beware of snakes without a rattle–baby rattlesnakes don’t have rattles and adult rattles can break off.

If a Bite Occurs

All rattlesnake bites are a medical emergency. Victims should seek medical attention in an emergency room immediately!

  • Try to calm the victim
  • Determine if a dry-bite occurred (with no venom injected) by assessing pain, swelling and muscle twitching. Those symptoms will occur if venom has been injected.
  • Immobilize and gently wash the bite area with soap and water and keep it lower than the heart.
  • If possible, stay put to avoid moving the muscle, which would spread the venom.
  • Mark the area of the swelling with a pen with the time on it.
  • Remove any watches, jewelry, etc. that might constrict swelling.
  • Apply a cold, wet cloth over the bit if possible.
  • Transport safely to the nearest emergency facility for further treatment (for anti-venom to be administered). If a victim is unable to reach medical care within 30 minutes, a bandage, wrapped two to four inches above the bite may help slow venom. The bandage should not cut off blood flow from a vein or artery. A good rule of thumb is to make the band loose enough that a finger can slip under it.

What to Avoid if a Bit Occurs

There are several things you should NOT do if bitten by a snake:

  • DON'T apply a tourniquet
  • DON'T pack the bite area in ice or ice water
  • DON'T cut the wound with a knife or razor
  • DON'T suck out the venom by mouth as infection can occur (avoid the common Sawyer Extractor)
  • DON'T let the victim drink alcohol

Other Yosemite Snakes

Non-venomous snake species exist, too, in Yosemite such as kingsnakes and yellow-bellied racers. Some species are rattlesnake lookalikes, such as the gopher snake that mimics the rattler by hissing, broadening its jaw to look triangular and shaking its tail in leaves.

View a list of Yosemite's other reptile species.

Last updated: June 1, 2023

Park footer

Contact Info



Contact Us