Pocket gophers (Thomomy spp.) have an important effect on reforestation in the Pacific Northwest through damage to conifer reproduction. Damage is most serious east of the Cascade Range in Washington and Oregon and northeastern California. Damage also has been reported in northern Idaho. The purpose of this report is to review pocket gopher problems in the Northwest, summarize present knowledge of gopher biology, outline current control methods, and suggest future research needs.

Reduction of pocket gopher damage to conifer seedlings is important to successful reforestation in many regions of the Pacific Northwest. The objective of this study was to determine the factors that influence the local distribution of the northern pocket gopher (Thomomys talpoides Richardson) in a forested region of south-central Oregon. Pocket gopher habitat was represented by 19 variables measured on 157 sites located in Klamath and Lake Counties, Oregon. The seasonal peak of mound-building activity occurred at the same period throughout the study area. No significant correlation was found between gopher-activity level and the number of animals captured per acre. A significant relationship was shown with the canonical correlation between the indexes to pocket gopher density (activity and catch) and the habitat. In general, an increase in activity and catch was shown with increasing elevation and slope, and a tendency towards more mesic timber types. The habitat preference of pocket gophers was associated significantly with more site disturbance and forb cover. This supports the assumption that site disturbances and increased forb cover caused by forest management activities improves pocket gopher habitat. A reduction in the amount of site disturbance, forb cover, or both, is suggested to decrease the probability of pocket gopher occurrence and associated tree damage.