Hazards to Grizzly Bears of Strychnine Baiting for Pocket Gopher Control

The Targhee and Bridger-Teton national forests in Idaho and Wyoming provide habitat for grizzly bears (Ursus arctos) from the Yellowstone National Park population (Anonymous 1979). Portions of the forests contain reforestation units scheduled for pocket gopher (Thomomys talpoides) control with strychnine alkaloid-treated grain, a practice used commonly to reduce damage to conifer seedlings by pocket gophers (Northwest For. Pocket Gopher Comm. 1976). In 1979, the U.S. Forest Service (USFS) asked the U.S. Fish and Wildlife Service (USFWS) for an opinion on whether grizzly bears would be affected by pocket gopher baiting projects on those units. This request was made in compliance with Section 7 of the Endangered Species Act of 1973 and amendments (Johnson 1979, 1984) because grizzly bears feed on pocket gophers and their food caches (Kendall 1980, Mealey 1980, Blanchard 1983) and thereby could be exposed to strychnine. We investigated the availability to grizzly bears of strychnine applied below-ground for control of pocket gophers. Specific objectives were to determine where pocket gophers died,