Test of a modified habitat suitability model for bighorn sheep

Translocation of bighorn sheep (Ovis canadensis) is time, labor, and cost i ntensive and, therefore, high levels of success are desirable. We tested a widely used habitat suitability model against translocation success and the n modified it to include additional factors which improved its usefulness i n predicting appropriate translocation sites. The modified Smith habitat su itability model for bighorn sheep was 64% accurate in predicting success or failure of 32 translocations of bighorn sheep into the Rocky Mountains, Co lorado Plateau desert, and prairie-badlands of six states. We had sheep loc ation data for 13 populations, and the modified habitat model predicted the areas used by bighorn sheep with greater than 90% accuracy in eight popula tions, greater than 55% accuracy in four populations, and less than 55% acc uracy in one population. Translocations were more successful when sheep wer e placed into discrete habitat patches containing a high proportion of lamb ing period habitat (>10% of suitable habitat, p = 0.05), where animals had a migratory tendency (p = 0.02), no contact with domestic sheep (p = 0.02), or greater distance to domestic sheep (>23 km, p = 0.02). Rate of populati on growth was best predicted by area of lambing period habitat, potential a rea of winter range, and distance to domestic sheep. We retested the model using these refined criteria and the refined model then predicted success o r failure of these 32 translocated populations with 82% accuracy.