A black snake with white stripes could be a California kingsnake, eastern kingsnake, common garter snake or striped racer. None of these snakes are poisonous or dangerous to humans, but they should be left alone if found in the wild.
California kingsnakes can be anywhere from 2 to 4 feet long and are commonly found on the West Coast of the United States and in southern portions of Nevada, Utah, Oregon, New Mexico and Colorado. The snake's diet consists of rodents, reptiles, birds and amphibians, and it is characterized by a solid black coloring with a pattern of white bands that run perpendicular to the snake's body.
The eastern kingsnake can be found throughout the eastern coastal regions of the United States. They are generally the same size as their California relatives and exhibit the same pattern of coloring. They are often referred to as chain kingsnakes due to their stripes.
The common garter snake can be found throughout North America and can be anywhere from 1 to 4 feet in length. These snakes normally feed on fish, frogs and insects. Their coloring pattern differs from kingsnakes in that their stripes run parallel to their bodies rather than perpendicular.
The striped racer is localized to the southern portions of California and Baja California. It can be 30 to 60 inches in length, with a single cream-colored stripe running down either side of its black body. Its diet consists of lizards, small rodents, small birds, frogs, salamanders and small snakes.