newly adopted bunny

Question
My husband and I adopted a bunny 3 days ago from a sad situation. His "mommy" died a few months ago and he's been in his cage at her home just waiting for someone to take him home. He's been to his vet and got a clean bill of health for a 6.5 year old bunny. He had REALLY long toe nails and he has allowed me to clip 3 feet so far with out much incident.

He's here now with his original cage and we've set up a special room for him so he'll be safely separate from our cats.

My question is that he seems to be sort of hostile. He has nipped my neck and arm (no blood just a pinching) when I've held him (sometimes he seems to enjoy being held and petted but then he gets aggressive) and he runs away from me and hides in his little bedroom attached to his cage. He also lunges at me and it seems that he either wants to headbutt me or bite me. It's a little scary!

How do I know what he needs and if I should pursue him or just leave him alone? I tried giving him treats and fruit but he ended up with diarrhea. He seems to be eating fine and drinking water.

We just want him to be happy and I don't know what to do to help him adjust to his new home.

Answer
Hi Katy
Thanks for your question. I am surprised that its a he thats showing this form of aggressiveness. My experience is that most of the aggressiveness is from females. I did have one male however who nipped and lunged and almost all of my female rabbits have done this at some point.
Neutering rabbits at sexual maturity will often help with this sort of behavior because often the aggressiveness develops at sexual maturity. If the pet is neutered then this behavior is avoided. But, with  your bunny being six years old, a lot of behavior will be habit formed already. Think of a dog that starts mounting. Once he forms the habit, then even if hes fixed he may continue mounting because hes formed the habit already. Your rabbit has a habit of being aggressive, but often this behavior is defensiveness rather than blatantly aggressive. I have heard of some rabbits who chase and nip their owners feet, so youre doing better than they are already. This behavior can be unlearned luckily, but it will take patience and perseverance on your part.
Dont avoid the animal. It will reinforce the behavior. Keep approaching him with treats and affection, speaking softly and he will overcome his fear. who knows what life was like at his previous home. He may not have been handled much, but it wont matter.
My male routinely nips me when he wants out of my arms. Hell nudge me firmly with his nose to get my hand away from him so he can jump down. Hes never drawn blood, its more of a warning bite. Believe me, they can draw blood when they want to.
I found a youtube instructional video on taming an aggressive rabbit. I watched it before and immediately thought of you and went back to find it. Heres the link:
http://www.youtube.com/watch?v=HxV0j7SwBbk
A limited domain for your bunny to hop around in will help because then you dont have to try to chase him or get him out from under sofas etc. I boarded off my kitchen to let my bunnies run in there so its easier. Sit on the floor and do your work etc. Rabbits are naturally curious and will want to come check you out and you can pet him and offer him treats. Hell learn youre not so bad.
Hope this helps! I know exactly the behavior youre referring to. Also, rabbits tend to be defensive over their cage. When moving things around in his cage or cleaning it, be sure hes out of it and it may spare you a nip or two.
Thanks for using the service.
A.