This book was first published in 1977. It deals with the importance of weed seed and grain-eating birds in natural and agricultural environments. These birds are to be found worldwide and are a component of man-made ecosystems where they are associated with man's main food crops. An analysis is made of their evolution and genetics, population dynamics, energy and food requirements, impact on ecosystems and control. Principles, procedures and basic data are presented that can be applied to the evaluation and control of pest species anywhere in the world. In this synthesis volume full use is made of the systems approach, the ecological and evolutionary aspects of the study are integrated. In linking the studies with fundamental work on bioenergetics, new insights are provided into the behavioural and applied aspects of granivory. Studies which encompass archaeological and anthropological investigations form a backcloth for the detailed interpretation of the population biology and bioenergetics of birds.