Great Basin Naturalist Memoirs


A habitat suitability Index Model (HSI), following the U.S. Fish and Wildlife Service HSI Model Series, is described for the black-footed ferret. The literature on which the model is based is reviewed, and model assumptions and structure are discussed. A realistic model is specified with variables and their functions that embody the critical spatial and resource heterogeneity characteristic of the broad geographic environment ferrets occupy. It assumes that ferrets can meet year-round habitat requirements within prairie dog colonies providing: (1) prairie dog colonies are large enough, (2) burrows are numerous enough, and (3) adequate numbers of prairie dogs and alternate prey are available. Five habitant variables are identified: V1 is the frequency distribution of colony sizes, V2 is the total area of colonies, V3 is burrow opening density, V4 is intercolony distance, and V5 is prairie dog density. Variables are compensatory. As more data become available and our understanding of ferrets expands, the basic model design can readily incorporate improvements without radical restructuring.