Why is my girl rabbit bitting and humping my guy rabbit !! my girl rabbit is elder after him and bigger ??

i already had a girl rabbit and looked lonely so i went and i bought a male rabbit and when i put them together the girl started humping and nibble on his back ! the guy is 2 months younger then her could this be the reason??
to be precise not the reseon.they will fight and they can do serius damage to each other.they will solely not fight on breeding seseon or u can make them like respectively other or probably they are fight for the place.girl wants all of the space and poor boy he doesnt enunciate anything cuz she is bigger.if they are from same mama maybe they wont breed but i m not sure.dont believe that i m not certain about the part 'if they are from same mama possibly they wont breed' .
Yep, that's the reason... She is humping him to show him that she is the boss. This will probably turn around as he get's elder and sexually mature, unless you get him neutered, which I recommend because otherwise you will be expecting babies every 30 days!
are you sure she is a she and not a he?
Animal instincts...plain and simple
Answers:    She's probably asserting dominance over him, any that or she is in heat.
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