Abstract

Integrating ecological information into conservation prioritization strategies is needed to facilitate land-use decisions about which habitat areas should be protected for imperiled species. Little effort has been directed toward incorporating variations in environmental determinants of patch occupancy across habitat types to optimize site selections for land acquisitions or habitat management activities, despite that variable other than patch area and isolation may significantly affect occupancy patterns of a species. This study examined how reserve networks differ in terms of sites selected, area reserved, and economic costs when comparing “traditional” systems (where only patch area and isolation affect occupancy) to “habitat-specific” systems that integrate variations in the environmental determinants of patch occupancy across distinct habitat types. Data on habitat variability and determinants of occupancy of an imperiled butterfly, the Carson Valley silverspot (Speyeria nokomis carsonensis) were integrated in an optimal reserve design procedure in Marxan. Analyses illustrated that reserve networks differed substantially between the traditional and habitat-specific systems. Cost efficiency (cost per area to protect habitat) was best for riparian habitats under the habitat-specific system, nearly 250% more efficient than the traditional reserve system. This study demonstrated that integrating environmental determinants of patch occupancy into site selection procedures more optimally selects suites of high quality habitat for an imperiled species. Moreover, these results provide land use decision-makers with cost-efficient prioritization strategies for habitat protection of an imperiled butterfly that can improve conservation actions and policies.

Key words: Speyeria nokomis, reserve selection, imperiled species, endangered species act, conservation planning, prioritization, cost-area efficiency.