The behaviour that evolves in response to competition depends on the ecological distribution of resources, and the physical and social attributes of competing organisms. In Chapter 2 we explored the ecological and social factors that influence the form and intensity of competition, and the consequences of competition for animal distributions and social behaviour. We have focused on scramble competition – a race for resources – which is the most basic of social interactions and generally involves the least-complicated behaviour. By contrast, contest competition – a fight for resources – which we addressed in Chapter 3, leads to more varied, durable and complex social relationships.