DOMINANCE HIERARCHY

=Dominance Hierarchies= [image:http://i.imgur.com/3EXyeHd.png?2] A dominance hierarchy is the organization of individuals in a group according to their dominance. These hierarchies are often linear, each individual dominating all individuals below him and not those above him. The most dominant individual is often referred to as the '''alpha male''' (or female), followed by the beta male and so on. These social structures were first observed in chickens and are thus sometimes referred to as a “pecking order”. The alpha male always eats first but also ensures that all members of the group get something, even the least dominant. He has a responsibility to ‘look after’ and make decisions for the group. The position of an individual in the hierarchy is determined by factors such as: Sex (males tend to be more dominant), size, age, health & fitness, experience (e.g. knowledge of the area), ability to produce offspring and kin alliances (relatedness to other more dominant individuals). Members of the same species are in competition for the same mates & resources. This would normally lead to aggressive behaviours, which could be a cost to the species. Social structures such as '''hierarchies lead to more stable groups in which aggression and fighting are reduced'''. ==Agonistic Behaviours== Dominance Hierarchies are maintained through '''agonistic behaviours''' such as '''aggressive displays''' and '''ritualised fighting'''. Animals may often look like they are fighting, but true fighting is actually very rare. Often quick slaps or bites keep subordinates in their place, but members of the group very rarely injure each other. "Fighting" is often ritualised in order to prevent injury, while still determining superiority in strength or agility. [image:http://i.imgur.com/3guR2pd.gif] Animals with large tusks, like walrus, often use these to push other individuals rather than actually pierce them. Horned antelope will gore an attacking lion, but when fighting each other never, direct their horns at the exposed flank (softer, more vulnerable area) of their opponent. Reindeer will first lock horns before pushing each other as a test of strength. This provides a way of predicting who would win in a fight, without the risk of injury or death. [image:http://i.imgur.com/Kg3cNJh.png?1] However, if the dominance of an individuals is challenged, this can threaten the stability of the entire group and is dealt with very seriously, and it may result in injury or even death. Young individuals must learn how to behave within the hierarchy. At first, inappropriate behaviour is usually tolerated. Most young have a signal that lets them ‘misbehave’. For instance, young chimps have a tuft of white hair and young pukekos do not have bright red beaks like their older parents. Once they have matured and they resemble mature individuals, inappropriate behaviour is no longer tolerated. [image:http://i.imgur.com/MJRF5xW.png?1] '''Dominance & Submissive Displays''' Even simpler behavioural displays are often use to maintain a dominance hierarchy. Agonistic displays are used assert dominance. These often include a more upright, aggressive stance. For instance, this first pukeko's upright stance and raised wing is a dominance display. Subordinate individuals (lower in the hierarchy) will respond with submissive displays (appeasement gestures) such as making themselves look small, bowing the head and exposing vulnerable parts. The second pukeko's bowed head is a submissive display. When young dogs roll onto their back, this is also a submissive / appeasement gesture. The young dog is exposing its vulnerable areas to communicate that it is no threat to your dominance! [image:http://i.imgur.com/nSKtbim.png?1]