The purpose of this 3-year project is to learn more about territoriality, using a population of birds in which cooperative family units defend large territories all year. The study is in part a continuation of a long-term study of population biology in a very illuminating species of bird, in which social cooperation characterizes the Florida race but is absent throughout the species' distribution in Western North America. For 17 years the investigators have monitored the details of births, movements, matings, territorial habits, and deaths of hundreds of scrub jays. This grant will permit continued monitoring of the population for three additional years. More important, it will allow a major investigation into the factors that cause some groups to defend large territories and others to be equally successful in small ones. The role of territory quality as it affects reproductive success will also be investigated. These objectives will be met by carefully measuring the habitat features and food resources of each territory (or representative ones) over all seasons for three years. The results will allow the investigators to estimate the relative quality of territories already mapped during the preceding 17 years of the study, because the habitat has remained essentially constant over that period. The final results will provide unique insight into the dynamics and roles of permanent territoriality within a non-migratory, socially cooperative animal species. The implications of this study will extend generally to a wide group of animal species that have evolved cooperative behavior as a means of coping with chronically crowded environmental conditions.
