I've been playing the game for just over a year. For the past six months, none of my animals have moved away. I don't know why this is. I even recently played DS to DS with a friend and thought this caused an animal to move when you did this, but nobody is moving from my town (or to my town). I've had the same 7 animals for the past six months now. When I played the game in the beginning, animals were coming and going every week or so. There are still lots of animals that haven't moved to my town yet, so it's not because I have had them all.
Is there anything I can do to change this? Thanks in advance.