Abstract
Conservation reserves have one of two major aims: to conserve species richness or to conserve a particular species. Diamond’s (1975) geometric design principles, once considered particularly apt for attaining the first aim, are now reassessed and considered to be not as helpful as was once thought. The use of “incidence functions” as an aid to designing reserves for the conservation of a particular species will usually result in an overestimate of the area necessary to support a self-sustaining population. In designing reserves for this purpose, nothing takes the place of sound ecological knowledge of the species concerned.