Rabbits do not typically bite for the fun of it. They have been known to bite if frightened or when attempting to defend either themselves or their belongings, including their space.
Rabbits prefer to be on the ground. A rabbit that isn't being held correctly will become scared and could bite in order to get the handler's hands to release them. This is why it is very important that small children do not handle or carry your rabbit around. Small children just do not have the dexterity to enable a rabbit to feel safe and secure and this could easily cause either or both to end up seriously hurt.
Cage protective behavior
Rabbits can become protective of their belongings, including toys, food and water bowls, bedding, etc. If you have a rabbit who bites when you try to clean his/her housing, then remove them before getting in there and cleaning things out. Rabbits like to have things a certain way; keep in mind their decor may not match your ideas.
After cleaning out their housing, try to put everything back in its rightful place. If your rabbit bites or charges when you are trying to feed (I have one like this) then pat the rabbit while placing fresh greens in their housing or food area. Distraction is a wonderful tool when dealing with a biter.
Another reason rabbits become cage protective is because their housing is too small and/or they are not getting enough play time out. Increasing play time and/or providing more spacious housing can really make a difference.
Raging hormones = raging bunnies
Rabbits can sometimes be aggressive because of raging hormones. Neutering or spaying your rabbit can help alleviate all sorts of bad behaviors. Just make sure you have the surgery performed by a rabbit knowledgeable vet.
Pay attention to me! (chomp!)
There are also those rabbits that will bite to get your attention. Bored buns get into all sorts of mischief. Being social creatures by nature, a friend could make a world of difference for your bun. It is emotionally and physically in the best interest of your rabbit. Many bad behaviors lessen in intensity or cease to exist once bun has a companion of his/her own.
How to stop the biting
Whatever the reason your rabbit it biting, there are several steps you should take consistently. Always give a loud eeeeep whenever they bite you. This is how rabbits communicate to one another that they have been hurt. Follow quickly with a firm "No Bite!" Once the behavior has stopped, be as quick to offer praise and love to reinforce their good behavior. Never use physical discipline in an attempt to correct your rabbit's unacceptable behaviors. You can also include a loud hand clap, stomp of your foot or loud whistle to get your rabbit's attention right before your "No Bite!" A soda can, with a few pennies tucked inside and the opening closed over with something like Duc Tape, can also be used to get bun's attention when the can is shaken. Consistency is an important factor when trying to get your rabbit to unlearn a bad behavior. This means that when your rabbit does a little nip that doesn't hurt at all, you follow the same steps as if it had been a hard one.
When approaching a rabbit that bites use a flat hand, palm side down, with fingers spread as wide as possible. Have the hand several inches above the head and bring it down gently onto the rabbit's forehead and nose from the front if possible. Pat and reassure bun that you mean it no harm and everything is okay with a loving, soothing voice. Never let anyone poke their fingers at your rabbit's face; they're very likely to get bit even if the rabbit isn't a known biter. Depending on the intensity of your rabbit's bite and your experience, you may want to use a pair of thick gloves at first to prevent any bites. When you become more comfortable, you can start practicing without the gloves. In time, the behavior will improve as the rabbit unlearns it with your help, patience and love.
Rabbits reach sexual maturity around 12 weeks, your buns could be starting to show hormonal/aggressive behavior now that they are that age. You should look into having them spayed
