Within North America, snakes in the genus Nerodia are native to the eastern and southeastern US, eastern Canada, and Mexico. Unlike the cottonmouth water moccasin (Agkistrodon piscivorus), which has not become established in California, water snakes are not poisonous and do not present a threat to human safety.

There are five subspecies of copperhead distributed according to geographic range: the northern, northwestern, southern and two southwestern subspecies.

The only dangerously venomous native snakes found in California are the seasnake, which occurs in the ocean off southern California and is rarely encountered, and the rattlesnakes, which occur throughout the state and have a rattle on the end of the tail.

The only venomous snakes in California are the rattlesnakes and there are eight species: the southern pacific rattlesnake, the northern pacific rattlesnake, the great basin rattlesnake, the western diamondback, the red diamondback, the sidewinder, the speckled rattlesnake, and the Mojave green rattlesnake.

Species of Snakes in California: Rattlesnakes

• The Western Rattlesnake (Crotalus Oreganus)
• Western Diamondback (Crotalus atrox)
• Panamint Rattlesnake and Southwestern Speckled Rattlesnake (Crotalus Mitchell)
• Sidewinders (Crotalus Cerastes)
• Mojave Rattlesnake (Crotalus Scutulatus)
• Red Diamond Rattlesnake (Crotalus Ruber)

Copperhead snake in tree is rare “They are basically terrestrial snakes, but it’s been known for decades (that they will climb trees).” Vandeventer said one of the more common times for copperheads to climb is during summers when cicadas emerge from the ground and cling to trees and bushes while they shed their shells.