I recently had a students' Mom ask me about the dynamics of the herd here at our place.  She was wondering how it is when a new horse is introduced.  Often times when bringing a new horse in, to join in with an existing herd, there can be a lot of chaos.  The Pecking order is quickly established. Through a fair amount of dirty looks, biting, kicking and running around, the herd boss is established.  The order becomes set from lead horse down to the last horse allowed to drink. At our place it is a matter of minutes until the hierarchy is established.