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Pocket gophers of concern to foresters in the Pacific Northwest belong to the genus Thomomys (13). The two species believed responsible for most conifer damage are the northern pocket gopher (T. talpoides) which occurs east of the Cascade mountains in Washington, Oregon, and south into the northeastern edge of California and the nearly identical Mazama pocket gopher (j_. mazama), which ranges throughout western Oregon and into north central California (13). Pocket gopher damage is best known to agriculturalists who for many years have suffered losses to root, hay, fruit, and bulb crops, as well as damage to irrigation canals (23). As early as 1922, Dixon (9) estimated gopher caused damage in California at eight million dollars annually. More recently, Marsh and Cummings (17) verified pocket gopher damage as a serious problem in California and other states. Literature referring to gophers and their control on agricultural and range lands is common because these are recognized problem areas. On the other hand, gopher damage to forest crops has little published documentation. Crouch (7), in 1942, listed mortality of forest trees from root gnawing in his summary of destructive activities of pocket gophers. Absence of yellow pine (Pinus ponderosa) seedlings in forest openings in the Ochoco National Forest, Oregon, was related indirectly to pocket gophers by Moore (19) in 1943. He reported a positive correlation between white footed mouse (Peromyscus spp.) occupancy of unused gopher runways and absence of seedlings. Papers on gopher damage in pine plantations by Dingle (8) in 1956 and by Hermann (1) in 1963 complete the pertinent early literature.