Covering the behavior and ecology of the northern fur seal, this book is a model long-term study of marine mammals, one that tests theory through both observation of undisturbed behavior and manipulative experiments on individuals. Here Roger Gentry draws on nearly two decades of research on three different islands to show how behavior among these seals changes with population size, sex ratio, and environment, to explain the behavior of the population beginning with individuals, and to generalize the results to other members of the eared seal family. In so doing, he offers one of the most comprehensive studies of its kind on any marine mammal species to date. Gentry shows that the species is driven by very different behavioral traits than have been assumed for it in the past. His book analyzes behavior on scales of hours to lifetimes, investigates the mating system, considers processes that underlie the mating system (site fidelity, behavioral estrus, and the development of territoriality), and addresses specific aspects of maternal strategy (female attendance behavior, pup growth, seasonal influences, and the effects of continental shelf width). Gentry contributes to knowledge about marine mammals by providing a very specific basis for interspecies comparisons, and he suggests a link between population trend and environmental regime shifts. He also guides the debate over seal mating systems from an interpretive to an empirical or experimental basis. Originally published in 1997. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.