San Diego gopher snakes have a range that is pretty warm year-round don't they? Makes sense that they would be less likely to brumate or go off feed in a season that isn;t very seasonal at all in their native habitat. As for bull snakes, their range is much more temperate, with areas of real winters. I have a WC black rat from central Oklahoma and last winter he stoped feeding in October and resumed in April -- this year, his second winter in my care, he's churning along fine taking a mouse every week. You might find that once your bull(s) is/are acclimated to 12 months of fairly constant temps, they'll pick up winter feeding fine -- but as the previous poster said, it won't hurt them at all to fast for a few month either.