A boa of cool northwestern North America, found from central California north into British Columbia, Canada and east to northern Nevada, Utah and Colorado.
Specimens from scattered populations in Southern California often are considered a full species, the southern rubber boa, Charina umbratica.
Rubber boas do well in a small terrarium of 10 gallons and need little in the way of special conditions. They thrive at low room temperatures (60 to 70 degrees Fahrenheit) and become stressed at higher temperatures. Special lighting or heating is not desirable. Keep the terrarium relatively moist and provide a bowl of drinking water. A once-weekly soaking may help prevent dehydration. Aspen or a loose, loamy soil makes a good substrate. The species is less shy when kept in subdued light. It must have one or several hiding places, where it will spend the day in a tight ball until it becomes accustomed to the terrarium. Wild-caught specimens seldom like to be handled and remain shy, but captive-bred specimens are easy to handle.
Adults feed well on small rodents, including pinky to small adult mice, and also take lizards. Wild-caught adults may insist on feeding on lizards or frogs and can be hard to convince to take rodents, even if mice are scented with a dead lizard. Newborns often are difficult to feed and are best left to advanced keepers.
Because it is a native species, rubber boas may require special permits to be kept in several western states, including California.