Humping behaviors

Question
Greetings.

I have 2 altered Netherland Dwarf rabbits. They are siblings that we have kept together, and they are both altered. Lately though, Jack has been pinning down Nat and going to town, frantically humping and then grunting and falling off to the side. Nat usually stands still and arches her back a little, but on a few occasions she's run off and backed herself into a corner. They've always gotten along, and were fixed about a year ago. Any clue as to why they're suddenly back into the humping game?

Answer
Hi,

even with fixed bunnies this occurs.  Sometimes change of seasons causes hormonal up and downs, usually fall and spring, I've noticed.  Sometimes it's about dominance and asserting such.  Sometimes it's because that's exactly what they intend to do.  With a bonded pair, that kind of behavior isn't unexpected.  Being fixed just means no multiple litters of babies and also they aren't doing it 24/7.  You couldn't keep them together in the same small space if the male wasn't fixed.  There'd be a lot of fighting because the female wold get so sick of it she'd have to in order to have a chance at it stopping.  Injuries would occur.

In fixed pairs they can control themselves more, their personalities are not totally overwhelmed by hormones.  But they will still do this as mature, adult rabbits that are bonded together.