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In social animals, the alpha is the individual in the community with the highest rank. Male or female individuals or both can be alphas, depending on their species. Where one male and one female fulfill this role, they are referred to as the alpha pair. Other animals in the same social group may exhibit deference or other symbolic signs of respect particular to their species towards the alpha or alphas.
In hierarchical social animals, alphas usually gain preferential access to food and other desirable items or activities, though the extent of this social effect varies widely by species. Male and/or female alphas may gain preferential access to sex or mates, and in some species only alphas or an alpha pair is permitted to reproduce.
The position of alpha also changes in some species, usually through a physical fight between a dominant and subordinate animal. Such fights may or may not be to the death, with relevant behavior varying between circumstance and species.
Social animals in a hierarchic community are assigned ranks for the purpose of ethological studies.
Beta animals often act as second-in-command to the reigning alpha or alphas and will act as new alpha animals if an alpha dies or is otherwise no longer considered an alpha. In some species of birds, males pair up in twos when courting, the beta male aiding the alpha male. The beta male is not generally allowed to mate with the female birds, but if the old alpha is removed or dies, he takes over the alpha's females, becoming the new alpha. It has been found that the social context of the animals has a significant impact on courtship behavior and the overall reproductive success of that animal.
Omega (usually rendered ω) is an antonym used to refer to the lowest caste of the hierarchical society. Omega animals are subordinate to all others in the community, and are expected by others in the group to remain submissive to everyone. Omega animals may also be used as communal scapegoats or outlets for frustration, or given the lowest priority when distributing food.
Common chimpanzees show deference to the alpha of the community by ritualized gestures such as bowing, allowing the alpha to walk first in a procession, or standing aside when the alpha challenges.
Gorillas use intimidation to establish and maintain alpha position. A study conducted regarding the reproductive behavior of male mountain gorillas (Gorilla beringei beringei) found further evidence that dominant males are favored to bear offspring, even when there is a greater number of males in a notably enlarged group size. The study also concluded that mating access dropped off less steeply with status; alpha, beta, and gamma showing more similar mating success, compared to what had been previously thought.
A study on the association of alpha male and female during the non-breeding season in wild Capuchin monkeys (Cebus apella nigritus) examined whether alpha males are the preferred mate for females and, secondly, whether female-alpha status and relationship to the alpha-male can be explained through the individual characteristics and or social network of the female. The results indicated that alpha male Capuchin are the preferred mate for adult females. However, only the alpha females had strong interactions with the alpha males by virtue of a dominance hierarchy among the females in which only the most dominant and strong females were able to interact with the alpha male.
In the past, the prevailing view on gray wolf packs was that they consisted of individuals vying with each other for dominance, with dominant gray wolves being referred to as the "alpha" male and female, and the subordinates as "beta" and "omega" wolves. This terminology was first used in 1947 by Rudolf Schenkel of the University of Basel, who based his findings on researching the behavior of captive gray wolves. This view on gray wolf pack dynamics was later popularized by L. David Mech in his 1970 book The Wolf. He formally disavowed this terminology in 1999, explaining that it was heavily based on the behavior of captive packs consisting of unrelated individuals, an error reflecting the once prevailing view that wild pack formation occurred in winter among independent gray wolves. Later research on wild gray wolves revealed that the pack is usually a family consisting of a breeding pair and its offspring of the previous 1–3 years.
In the case of other wild canids, the alpha male may not have exclusive access to the alpha female; moreover, other pack members may guard the maternity den used by the alpha female; such is the case with the African wild dog, Lycaon pictus.