Why Is My Male Cat Mounting My Other Male Cat. Notably, intact males are generally more aggressive, frequently engage in objectionable marking and mounting behavior, and have a constant eye for the door, particularly when a neighboring queen is in heat. If the cat he attacks is one he considers a threat to his alpha status, he may be doing this to assert his role as top cat.

I have often heard owners describe the aggressive behavior of their neutered male cat toward their neutered female cat in in terms that sound, for all the world, like male mounting behavior. Make sure the cat doing this behavior has plenty of playtime, toys, and stimulation. When the male cat is neutered, on the other hand, they lose the urge to do this.