Odor preference and taste-potentiated odor aversion in grizzly bears

Odors are important drivers of behavior for many species. Bears use odors to make critical foraging decisions. Little systematic work has been conducted to quantify odor preferences in bears. We tested 12 odors that were purposefully selected as possible attractants, repellants, or neutral with captive grizzly bears (Ursus arctos horribilis) at the Washington State University Bear Center. These odors included bear lure, honey, lemon oil, fish oil, star anise, and conspecific urine, among others. The bears preferred honey and bear lure over all other odors, while lemon oil remained neutral. We subsequently used those results to determine whether we could establish a conditioned food aversion to an odor (taste-potentiated odor aversion; TPOA). We used a high value food (Froot Loops®) and the aversive agent thiabendazole (TBZ) paired with lemon oil as an unfamiliar odor cue. The aversion was strongest in wild-born bears compared with captive-born bears. Overall, aversion strength was weaker during autumn hyperphagia compared with the summer. More exposures to TBZ were given to bears with weaker aversions for reinforcement, resulting in a negative correlation between number of treatments and aversion strength. However, grizzly bears are very capable of forming an association between a neutral odor and an aversive agent when sprayed on food and thereby can avoid eating treated food. Thus, TPOA could be a nonlethal method used to reduce economic losses to crops, bear–human conflicts, and bear mortalities.