The Bull Snake, Pituophis catenifer sayi, is just one of the several subspecies of Gopher Snake, Pituophis catenifer. Most subspecies look very similar, identical without careful scrutiny. A young Bull Snake will often look like any of the other Gophers. Yours is probably a Pacific P c catenifer or an integrade between catenifer and the Great Basin subspecies deserticola. I am not sure if pure deserticolas are found in N Calif. You are a long ways away from the range of the Bull Snake subspecies. Pine Snakes are a different species but the same genus as the Gophers. Pines are not found in the western US. Rat snakes do not belong to the Pitophis genus and they are not found in Calif. or Nevada.
Anyway, Gophers make fine pets and most tame down nicely. Some do seem to have individual temperaments however but none are dangerous. Their husbandry is typical for colubrids, similar to that for Kings, Rats etc.
Randy
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Firehouse Herps