A word of caution for the family relocating to California: load Fido and Socks into the minivan, but leave the gerbil at home.

Many pet lovers are surprised to learn that these Asia natives are banned in California. “People are notoriously careless,” says Phil Nelms, a captain in the California Department of Fish and Game’s Wildlife Protection Division. “The gerbil has the potential to destroy the kangaroo rat,” a California native with five species on the federal endangered list. Wild gerbils, Nelms says, could monopolize the kangaroo rats’ food and water supplies and take over their nests. The agency’s concern is that gerbils will escape or, more likely, be released into the wild by owners grown bored.

“It has no natural checks and balances,” Nelms says of the gerbil, which is joined by the lately popular ferret on a list of banned animals originally drafted by the state Legislature in 1933. Conspicuously missing is the gerbil’s cedar-chip brethren, the hamster, allowed because the state considers it less of a threat. Nelms admits this is debatable, but says, “Hamsters have been so interbred and are so far removed from their original wild stock, they wouldn’t survive 24 hours in the wild. You probably can’t say the same thing about gerbils.”