FLAVOR AVOIDANCE-LEARNING AND ITS IMPLICATIONS IN REDUCING STRYCHNINEBAITING HAZARDS TO NONTARGET ANIMALS

In reforested areas, underground strychnine baiting to control pocket gophers (Thomomys mazama) poses a hazard to golden mantled ground squi rrels (Spermophilus lateralis) and yellow pine chipmunks (Eutamias amo enus). We designed this study to assess whether: 1) chemical insensiti vity to bitter tastes might explain the ingestion of strychnine; 2) po cket gophers would avoid four bitter-tasting compounds: quebracho (QUE B), sucrose cotaacetate (SOA), quinine hydrochloride (QHCl), and denat onium benzoate (DB); and 3) nontarget species could be trained to avoi d strychnine paired with the most aversive compound. Our results showe d that while all species readily consumed strychnine, the nontarget sp ecies could be conditioned to avoid it. Moreover, while high (0.1%) co ncentrations of DB, quinine hydrochloride, and quebracho reduced consu mption by pocket gophers, 0.05% DB was inoffensive. Nantarget animals readily avoided 0.05% DB, and avoidance was stronger after conditionin g. Together, our results suggest that ail of the rodents tested are in sensitive to strychnine, high concentrations of some bitter tastes may be effective pocket gopher repellents, and lower concentrations of DB may selectively repel nontarget animals from strychnine baits. (C) 19 98 Elsevier Science Inc.