Indicator, umbrella and flagship species: the concepts and their applications in conservation biology

In recent studies, surrogate species have been increasingly employed as a shortcut to monitor or solve conservation problems. Three types of surrogate species have been recognized, i.e. indicator species, umbrella species and flagship species. Indicator species have been used to assess the magnitude of anthropogenic disturbance, to monitor population trends in other species, and to locate areas of high regional biodiversity. Umbrella species have been used to delineate the type of habitat or size of area for protection, and flagship species have been employed to attract public attention. We attempt to provide some clarification and guidelines for the application of these different terms. By comparing these concepts, it becomes clear that both the goals and selection criteria of different surrogate classes differ substantially, indicating that they should not be conflated and considered interchangeable.