Association for Public Policy Analysis & Management

Networks of protected lands, such as the National Wildlife Refuge System (NWRS), are charged with managing habitat for Threatened and Endangered (T&E) species and for other species of concern, yet they must often contend with external factors that threaten habitat quality.  Wildlife refuges themselves are protected from development, but they can be vulnerable to the effects of land use outside of their borders, such as habitat fragmentation from development and polluted runoff from agricultural land, and they are also vulnerable to extreme weather events, such as drought and flooding, and other habitat disturbances.  Being able to identify threats to habitat quality can assist policymakers in determining where to locate new refuges, whether to augment existing refuges, how to collaborate with government agencies and private organizations that control surrounding lands and how to efficiently allocate limited staff and management resources across refuges in the system.  This study assesses the influence of land use, extreme weather and other threats to the quality of habitat for threatened and endangered species in the NRWS. The managers of 400 wildlife refuges in the NWRS were surveyed in 2008 about habitat quality for each of T&E species for which their refuge manages habitat.  A Geographic Information System (GIS) was used to assess potential threats to habitat quality, such as population density of surrounding land (using U.S Census data), extent of nearby cultivated cropland (using the National Land Cover Database) and drought indices (using the Palmer Drought Index).  Data on staffing levels and other refuge characteristics were obtained through administrative data.  A hierarchical logistic regression model was developed to predict land managers' assessment of habitat quality for each T&E species they manage as a function of these characteristics.  The results highlight the importance of quantitative assessments for the purpose of managing protected areas and demonstrate the role of key factors in influencing habitat quality for critical species.