Coloniality is a conspicuous form of social organisation in several avian taxa, particularly in marine and freshwater birds, yet the adaptive signifigance of colonial breeding remains poorly understood. This book examines the general features of coloniality within an evolutionary context to enable a better understanding of the process that have moulded this social breeding system in birds, its maintenance, its determinants, and its constraints. Chapters on mating systems, foraging, parental care, communication skills, and information transfer aim to elucidate the adaptive value of coloniality for breeding and the exploitation of food resources are included.