Laboratory Studies of More Durable Baits for Controlling Pocket Gophers

A laboratory study of 68 Botta's pocket gophers (Thomomys bottae) was carried out to compare the preference for 20 different nontoxic baits and the preference and efficacy of 14 different toxic baits. All baits were designed to be more durable (i.e., longer lasting) than loose grain baits to increase the chance that one baiting might successfully control any new gopher invader that moved into an unoccupied burrow system. Bait types ranged from pure paraffin cubes, polyethylene bags of grain bait (plain or coated with paraffin and carrot powder), and paraffin grain baits (3.4 g and 10 g). Wide differences were found in bait preferences and in the mortality achieved by the various baits, but generally the bagged baits outperformed the others tested. Some gophers appeared to develop a tolerance for strychnine but bait shyness was not indicated. After being buried 5 months in the field, bag baits and pure paraffin blocks were in good condition, and microwaved whole wheat paraffin baits were only moderately moldy; but paraffin baits containing wheat, ground oats, microwaved oat groats, or carrot powder were mostly mildewed after 1 month underground. Proc. 15th Vertebrate Pest Conf. (J. E. Borrecco & R. E. Marsh, Editors) Published at University of Calif., Davis. 1992