male cat mounting other male cat

My girlfriend moved in with her two cats (one male, one female). I have one male cat as well. We introduced them through the usual means and everything seemed to be fine for about a month. Now, my cat (the male) has been mounting her male cat from behind as if he is having sex with him.

I'm not concerned about them hurting one another, but I did want to know if this sort of behavior will stop after time? I have heard that this is sort of a dominace issue, but my girlfriend's male is so submisive.

Advice please?

Mark

I believe that if the males are neutered you may have fewer problems.

I'm sorry, I forgot to mention they are both neutered.

Sorry,
Mark

Mounting is a dominant behavior in dogs but not cats. The male that is doing the mouting is just very hormonal. Some male cats still retain the instinct. Heck, some will even try and mount a sock

How long ago were the boys neuterd?

Darwin, the new male was neutered about two years ago. He's about 2.5 now. Mister, the resident male was neutered about 5 years ago. He's almost six now. Mister was neutered *after* he was sexually mature.

Thanks,
Mark

Oh my gosh...I would have thought 'it' was out of his system by now!

My 5 year old male cat does the same to my 2 year old male cat from time to time. Both were neutered as kittens. If it's not a dominance issue like Sandie says, then I don't have a clue for you.