This talk, which is the result of a 30-year study, will discuss the factors that influence the population levels of Sparrowhawks, including habitat, food supply, and nest sites. It will discuss the lifetime reproduction of individuals, and age-related changes in the reproduction, survival and behaviour of individuals, and how these measures relate to territory quality. Many findings from this species are also applicable to other birds of prey, and also to some non-raptorial birds.