It sounds like he needs more bunny appropriate toys. Rattles and things like that aren't generally stuff that bunnies like. Cardboard boxes, grass mats, and organic baskets that they can chew on and destroy are much more fun for rabbits. Chewing is how they amuse themselves, and he doesn't have much to chew for fun.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry