Social Groups 
                       Many types of animal live in social groups. A social 
                       group can consist of as few as 2 members ranging to 
                       several thousand. To live and interact successfully in 
                       these groups animals have developed behaviours and 
                       signals. 
        Social hierarchy 
  • Social hierarchy is a system where members of a group 
   are organised in order of rank 
  • An individual of a higher rank dominates and exerts 
   control over lower ranked individuals 
    Advantages of Social Hierarchies 
  • Systems of social hierarchies increase a species’ chance 
   of survival
  • Aggression is ritualised and involves less cost 
  • Real fighting is minimised 
  • Serious injury is normally avoided
  • Energy is conserved
  • The strongest animals are more likely to pass on their 
   genes
        Bird dominance 
  • When newly hatched birds are kept together one bird 
   will emerge as the dominant member
  • This bird will peck and intimidate other birds 
   without being attacked back
  • This bird will get first choice of available food
  • The next ranked bird is able to peck all birds below 
   without being attacked and so on
  • This is called a pecking order
              Mammals 
   • Social hierarchies exist in some groups of mammals
   • Wolves live in packs with one male being dominant to the others
   • The dominant male is afforded certain rights such as first choice 
    of food and mates 
   • The dominant male uses social signals to exert his rank
   • He will use ritualised threat gestures to demonstrate his 
    dominance 
   • Other wolves demonstrate their acceptance of his dominance by 
    making submissive responses