Willife management is the process of keeping certain wildlife populations, including endangered animals, at desirable levels determined by wildlife managers. Wildlife management is interdisciplinary, integrating science, mathematics, imagination, and logic. It deals with protecting endangered and threatened species and subspecies and their habitats, as well as with non-threatened agricultural pests and game species. Aldo Leopold, one of the pioneers of wildlife management, defined it as "the art of making land produce sustained annual crops of wildlife."