Yosemite National Park is home to only one rattlesnake–the Northern Pacific rattlesnake (Crotalus oreganus 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.
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.
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
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 jewelry that might constrict swelling.
Do not cut the wound with a knife.
Do not pack the bite area in ice.
Do not suck out venom by mouth (avoid the common Sawyer Extractor).
Do not use a loose constricting band around bite to minimize venom spreading because this can be detrimental.
Get to a hospital as quickly as possible for anti-venom to be administered.
Note: 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.
(209) 372-0200 The public information office is open from 9 am to 5 pm Pacific time (closed for lunch). Once connected, dial 3 then 5. If the ranger is already on the line, you'll be returned to the main menu. If the ranger is not there, you can leave a message and we will return your call.