The Southern Pacific Rattlesnakes range is from coastal Southern California to northwestern Baja California, Mexico, and they are commonly found on prairies or sage scrub/grassland areas, especially near rocky outcroppings. into California from elsewhere.) In recent years, the southern Pacific rattler has become an increasingly dangerous snake in the southwestern region of California and in the northern part of Mexico's Baja Peninsula. Starting each spring, Southern Pacific rattlesnakes (Crotalus oreganus helleri), the most common species in the L.A. area, come out of hibernation to mate. Rattlesnakes are part of life in Southern California, but there are a lot of misconceptions about our slithering friends. The California venomous snake list includes the western rattlesnake, western diamondback rattlesnake, red diamond rattlesnake, sidewinder, southwestern speckled rattlesnake and … Squamata >> Viperidae >> Rattlesnake Database >> Southern Pacific. Southern Pacific Rattlesnake Coiled against a Log. Between the three, the Western Diamondback is generally considered the most aggressive. So, I did some research on the subject and this is what I found out. So, I did some research on the subject and this is what I found out. The rattlesnake is a highly venomous snake. There are four species of rattlesnakes found in San Diego County. Starting each spring, Southern Pacific rattlesnakes (Crotalus oreganus helleri), the most common species in the L.A. area, come out of hibernation to mate. It is a pit viper, and it seeks out prey by using a heat-sensing organ that can be found on both sides of the snake’s face between the nostrils and the eye. California rattlesnake species include the northern Pacific rattlesnake (in northern California), and the Western Diamondback, Sidewinder, Speckled rattlesnake, Red Diamond rattlesnake, Southern Pacific, Great Basin rattlesnake and the Mojave rattlesnake (all found in Southern California). The rattlesnake is a highly venomous snake. When backpacking or hiking in Southern California, one of my biggest concerns is always rattlesnakes. Juvenile Northern Pacific rattlesnake, Sacramento County, California The color pattern of the typical form, C. o. oreganus , has a dark-brown, dark-gray, olive-brown, or sometimes black or pale yellowish ground color overlaid dorsally with a series of large, dark blotches with uneven white edges. The Red Diamond rattlesnake is the largest species in the county. Southern Pacific Rattlesnake - Crotalus viridis helleri. The Southern Pacific rattlesnake, one of the largest rattlesnakes, is one of several dangerously venomous rattlesnakes species native to California. The Southern Pacific Rattlesnakes range is from coastal Southern California to northwestern Baja California, Mexico, and they are commonly found on prairies or sage scrub/grassland areas, especially near rocky outcroppings. Southern Pacific Rattlesnakes can be found throughout California, including the St. Francis Dam site. It is a pit viper, and it seeks out prey by using a heat-sensing organ that can be found on both sides of the snake’s face between the nostrils and the eye. This snake is actually a subspecies of species Crotalus viridis. Between the three, the Western Diamondback is generally considered the most aggressive.