A dominance hierarchy, formerly and colloquially called a pecking order, is a type of social hierarchy that arises when members of animal social groups interact, creating a ranking system. In social living groups, members are likely to compete for access to limited resources and mating opportunities. Rather than fighting each time they meet, relative rank is established between members of the same sex. Based on repetitive interactions, a social order is created that is subject to change each time a dominant animal is challenged by a subordinate one. In mammals, a dominant individual is sometimes called an alpha, and the lower rank is sometimes termed a beta.
