The capacity of the national wildlife refuge system to conserve threatened and endangered animal species in the United States

The US. Fish and Wildlife Service manages the 38-million-ha National Wildlife Refuge System, which is devoted primarily to wildlife conservation. I examined the capacity of the refuge system to conserve federally listed threatened and endangered animal species. Population viability data for a random sample of these species were analyzed and extrapolated. Three levels of population viability were distinguished: outbreeding, demographic, and evolutionary. One hundred eighty-six of the 514 federally listed animal species reside in whole or in part on the refuge system. Of these 186 species, approximately 81, 101, and 107 are supported by the system at evolutionary, demographic, and outbreeding viability levels, respectively. These figures correspond to 16%, 19%, and 21% of the 514 federally listed animal species, respectively. Various federal policies and programs facilitate the expansion of the refuge system, but other federal policies and programs facilitate economic growth, which tends to require the conversion of habitats faster than it provides for habitat conservation. Therefore the long-run effectiveness, extent, and endurance of the refuge system will depend largely on macroeconomic policy context.