Efficacy and Costs of Four Rodenticides for Controlling Columbian Ground Squirrels in Western Montana

Efficacy and costs of four rodenticides for the control of Columbian ground squirrels were compared in western Montana. Reductions in surface ground squirrel activity and costs per 100 burrows treated for the various treatments were: 1080 oat groats 99.6%-$3.11, gas cartridges 72.2%-$26.57, strychnine oats 64.2%-$3.06, zinc phosphide cabbage 60.9%-$8.48, zinc phosphide oats 41.3%-$3.15, and strychnine cabbage 14.4%-$9.58. Surface deaths associated with 1080 amounted to 2.35 ground squirrels per 100 burrows treated. Above ground death rates for the remaining treatments were negligible or nonexistent for both target and non-target species. One white-footed deer mouse was found dead on the strychnine cabbage treatment site. Results of this study indicate that 1080 is the most effective agent for the control of Columbian ground squirrels