I recently bought two young boars to introduce to my older boar since his companion died. Right now, they're set up in two identical cages with bars separating the younger ones from the older one. Everything seems to be going fine except for one of the younger ones is biting the divider bars a lot, especially when the older one is near. The older doesn't seem bothered by it and just continues on with his day. Is the bar chewing a sign that the younger one wants to be in with the older one, or a sign of aggression?