I don't know about any background to this I'm afraid, but I would guess that he's marking it as his territory. Is he neutered? Neutering should help as he will lose the hormonal urge to mark his territory. It sounds as if you have just moved him from another area - so if he is feeling insecure he will pee and poop everywhere so that it smells of him and helps to make him feel more settled.
It all sounds perfectly normal and exactly what I'd expect of a bunny in a new territory. Hopefully it will settle down in a few weeks if he has used a litter area before, and if he isn't neutered, having that done should help too.