Behavioural ecologists study the strategies that individual animals use to maximize their genetic representation in future generations; conservation biologists study small populations and attempt to stem the tide of species extinctions. In the last few years, a handful of behavioural ecologists, increasingly concerned about species losses, have begun to address issues in conservation biology. Using data collected in the course of their fieldwork on mating systems, foraging behaviour, or habitat preferences, or simply by working on an endangered species, they have started to apply their findings to models of population growth and effective population size, hands-on management, and developing conservation strategies. This edited volume is the first attempt to link these disciplines formally.