http://www.sandiegorabbits.org/companion-your-rabbit/bunny-bonding-basics
Like any relationship, a new pairing of rabbits can be slow to develop or be love at first sight. Almost all rabbits can work out their differences and enjoy the companionship of another rabbit. Still, the process of bonding two rabbits will take time, patience, commitment and some work on your part.
The following tips are from HRS volunteers who have matched up many, many rabbits over the years.
• Relax! Take a deep breath and relax. If you are a nervous wreck, the rabbits will be, too.
• Males & females: We seem to have the best luck in pairing neutered males with spayed females. Usually the males appear to be dominant at first with their excessive mounting. The female will put up with this for a short while, but will usually assert her dominance by mounting the male or nipping him to show she is the one in charge. At this point, the male usually backs down and they start on the road to friendship. Same-sex pairing is not out of the question, but requires at least one submissive rabbit in the group and a little more patience on your part.
Spaying & neutering: It is considerably easier if BOTH rabbits in the pairing have been fixed. In fact, you may not be successful with the match if they are not. Once fixed, you are working with temperaments and personalities, not hormones and uncontrolled desires! If the rabbits are newly altered, (6 months or less) they may still be quite amorous towards each other. This behavior should dissipate the longer they are fixed. Please see our handout “Altering your Rabbit’s Future” for more reasons to alter your companion rabbit and for our list of recommended veterinarians.
NOTE: If your rabbit has just been spayed or neutered, it is highly recommended that you wait at least two weeks (a month is better) before introducing him or her to another rabbit. This will prevent the male from possibly impregnating an unspayed female (or continuing to exhibit hormonal behavior), and a newly spayed female from fighting off the male due to being uncomfortable from her recent surgery.
• Time: Although the average length of time until most rabbits are pretty well bonded is about two weeks, we have seen rabbits take as little as one afternoon or as long as many months to become friends. Neutral territory is imperative. YOU MUST put the rabbits (and keep the rabbits) in a small, neutral area for about one week. Beginning the bonding in a small, neutral territory is vital to this relationship working out. A kitchen, bathroom, or portable exercise pen all work well. DO NOT put them in a cage together until they have been getting along perfectly for several days. If a serious fight breaks out in a cage, it is generally difficult to separate them and injuries can occur.
• Fighting, nipping & mounting: Although these behaviors may look similar to you, they are all very different and it is important to recognize the different ways rabbits speak. Fighting is usually an instant, purposely vicious attack. Rabbits sometimes attack the other rabbit’s face, underside or genital area. DO NOT separate the rabbits unless they are truly fighting. Every time you separate the rabbits, you will have to re-introduce them, making this process take even longer.
Nipping at each other in a playful manner is not usually serious and is done for several reasons. Remember, rabbits sometimes communicate by nipping and this could be done to say “Hey, pay attention to me” or “Who are you?” and “Get out of my litterbox!” This too should dissipate as they learn how to approach and communicate with their new partner.