Spatial optimization of prairie dog colonies for black-footed ferret recovery

A discrete-time reaction-diffusion model for black-footed ferret release, population growth, and dispersal is combined with ferret carrying capacity constraints based on prairie dog population management decisions to form a spatial optimization model. Spatial arrangement of active prairie dog colonies within a ferret reintroduction area is optimized over time for maximum expected adult ferret population. This modeling approach is applied in an exploratory case study to a black-footed ferret reintroduction program in Badlands National Park and Buffalo Gap National Grassland, South Dakota. The model is currently being used to evaluate prairie dog population management alternatives and captive-bred ferret release locations for the Buffalo Gap National Grassland. This approach is also being adapted for use on other grasslands and with other species in the northern Great Plains. Early in 1987 the black-footed ferret (Mustela nigripes) became one of the world’s most endangered mammals when the last known free-ranging member of the species was taken into captivity (Thorne and Belitsky 1989). The Wyoming Game and Fish Department was successful in breeding six of the surviving ferrets in captivity (Clark 1989). This set the stage for a national recovery program of releasing captive-bred ferrets back into th