The desert tortoise Gopherus agassizii is found in both the Sonoran and Mojave Deserts, as well as tropical Mexico. The ecology, physiology, and behaviour of the Mojave populations are quite different from those of their Sonoran cousins, which have been studied much less. This book presents the first comprehensive summary of the natural history, biology, and conservation of the Sonoran and Sinaloan desert tortoises. It synthesises a vast amount of information on population ecology, activity and behaviour, based on decades of research.