Conservation and management for multiple species: Integrating field research and modeling into management decisions

Multiple-species reserves aim at supporting viable populations of selected species. Population viability analysis (PVA) is a group of methods for pred icting such measures as extinction risk based on species-specific data. The se methods include models that simulate the dynamics of a population or a m etapopulation. A PVA model for the California gnatcatcher in Orange County was developed with landscape (GIS) data on the habitat characteristics and requirements and demographic data on population dynamics of the species. Th e potential applications of this model include sensitivity analysis that pr ovides guidance for planning fieldwork, designing reserves, evaluating mana gement options, and assessing human impact. The method can be extended to m ultiple species by combining habitat suitability maps for selected species with weights based on the threat faced by each species, and the contributio n of habitat patches to the persistence of each species. These applications and extensions, together with the ability of the model to combine habitat and demographic data, make PVA a powerful tool for the design, conservation , and management of multiple species reserves.