In 1976, we began a comprehensive evaluation of "Vexar" seedling protectors as a means of reducing damage to conifer seedlings by pocket gophers (Thomomys spp.). The protectors are cylinders of plastic netting that gradually decompose in sunlight. The evaluation is being conducted on four national forests in three western states. Three conifer species, lodgepole pine (Pinus contorta), ponderosa pine (P. ponderosa), and Shasta red fir (Abies magnifica var. shastensis), are under study. After two growing seasons, gophers have caused only 5 percent mortality among "Vexar"-enclosed seedlings compared to 20 percent mortality among unprotected seedlings. In addition, stocking and heights of protected seedlings are better than those of unprotected seedlings. Problems associated with the use of "Vexar" included compression of the protectors by snow, breakage of the plastic during subfreezing temperatures, and protrusion of seedling terminals through mesh openings; however, these problems have been minor thus far. Information on long-term effectiveness and cost efficiency is still needed before we can recommend operational use of "Vexar" protectors for pocket gopher damage control.

Laboratory bioassays and field tests were conducted to determine if zinc phosphide baits would control pocket gophers in forest plantations. Zinc phosphide baits generally were less effective than the strychnine alkaloid-oat bait commonly used by forest managers to control gophers. However, a carrot bait with 0.75% zinc phosphide showed potential as a substitute for strychnine. Size of carrot bait and grooming activity of gophers were identified as important factors affecting efficacy of baits.

Damage to conifer seedlings by pocket gophers (Thomomys spp.) is a major factor limiting reforestation in the western United States. To control gopher populations and reduce damage, the U.S. Forest Service annually treats thousands of hectares with strychnine alkaloid bait. Because an underground application of strychnine bait could pose a threat to other species, we monitored small mammal populations before and after a baiting operation conducted in 1979 on the Targhee National Forest, Idaho. Although two deer mice (Peromyscus maniculatus) recovered within baited areas were killed by strychnine, live-trapping revealed no differences in small mammal populations before and after baiting. Thirty yellow pine chipmunks (Eutamias amoenus) and one northern flying squirrel (Glaucomys sabrinus) were fitted with radio transmitters before treatment. Twenty-four of the chipmunks, and the flying squirrel, survived to the end of the study. Transmitter signals were lost on three chipmunks before treatment and they were unaccounted for. Two chipmunks died during the study and contained strychnine residues in body tissues. The remaining chipmunk appeared to have been killed by a predator.