poor scared buns!
my dog spent the first four years of her life in anchorage, alaska, where there are no thunderstorms. poor thing did not handle the oklahoma thunderstorms well when we first moved here! we were able to desensitize her, though, and they don't phase her any more. i don't know if something like that would work for a rabbit, though. we got a cd with storm sounds on it, and started playing it around her. at first, we kept the volume really low, and only a few minutes at a time. gradually, we increased the volume and duration. we used lots of praise and treats when she was calm. during a real storm, or if the cd made her nervous, we used distraction methods (favorite toys, games, food, ect) or benign comfort (allowing her to sit with us, touching her gently when needed, but no big fuss). it wasn't long before she got over her fear. like i said, i don't know if this would work for a rabbit, but it couldn't hurt to try!