On the Use of Surrogate Species in Conservation Biology

TLDR

Conservation biologists use surrogate species—indicator, umbrella, flagship—to monitor disturbances, track populations, delineate habitats, and attract attention, but terminology is often confused and applied inconsistently. The authors aim to clarify and provide guidelines for distinguishing and applying these surrogate species concepts. They review each surrogate type, describe its typical use, and examine the criteria managers and researchers employ to select appropriate surrogates. Their comparison shows that surrogate classes differ in goals and selection criteria, so they should not be conflated; careful definition, explicit criteria, pilot testing, and cautious use are essential for effective conservation.

Abstract

Abstract: Conservation biologists have used surrogate species as a shortcut to monitor or solve conservation problems. 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. Unfortunately, there has been considerable confusion over these terms, and several have been applied loosely and interchangeably. We attempt to provide some clarification and guidelines for the application of these different terms. For each type of surrogate, we briefly describe the way it has been used in conservation biology and then examine the criteria that managers and researchers use in selecting appropriate surrogate species. By juxtaposing 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. This can be facilitated by first outlining the goals of a conservation study, explicitly stating the criteria involved in selecting a surrogate species, identifying a species according to these criteria, and then performing a pilot study to check whether the choice of species was appropriate before addressing the conservation problem itself. Surrogate species need to be used with greater care if they are to remain useful in conservation biology.