Grizzly Bears for the Bitterroot: Predicting Potential Abundance and Distribution

The United States Fish and Wildlife Service has proposed restoring grizzly bears (Ursus arctos) to the Bitterroot ecosystem of central Idaho and western Montana, where grizzly bears were extirpated by 1932. We based estimates of future grizzly bear population size and distribution in the Bitterroot ecosystem on resource selection functions developed for the Yellowstone ecosystem and Swan Mountains in northwestern Montana. This method yielded an estimate of 321 grizzly bears in the Bitterroot recovery area. Our analysis suggests that habitat attributes, particularly the paucity of roads and human developments, will help to ensure a viable population of grizzly bears in the Bitterroot ecosystem.