Last week we integrated our 8 week old does with our 7 month old does and other than a few squeaks and a little kerfuffle all has seemed well. This morning I spotted 9 week old Juno vigorously mounting the back of my dear 'fat mouse', 7 month old Circe. At first I blanched thinking that we had been sold a rogue male (Juno is the dominant one in the Newbies), then I read on here about dominance mounting especially at the time of estrus. Do contributors think that this is the most likely scenario and if so does it affect mouse relationships with each other in the long term?