CONICET | Buscador de Institutos y Recursos Humanos

tAttempts to control cougar (Puma concolor) and culpeo fox (Pseudalopex culpaeus) popu-lations in Patagonia through poisoning, negatively affects grey foxes (Pseudalopex griseus)and many other non-target species. It is therefore advisable to develop selective predatorcontrol methods. Among a wide range of potential methods, are those based on manip-ulating the behaviour of non-target species. Conditioned taste aversion (CTA) developswhen an animal associates taste with subsequent illness, and, after recovery, avoids thereferent taste. Food aversions can be potentially useful in efforts to reduce losses of non-target species when lethal baits are distributed to control other predators. We evaluatedtwo ways to add the aversion agent Levamisole hydrochloride to a bait to generate CTAin grey foxes. We established one control (without Levamisole) and two treatments: plainLevamisole and an ion-exchange resin complex (resinate: Amberlite®IRP-64) aiming tomask the taste of Levamisole. Foxes that ate plain Levamisole baits, ate fewer baits thanthose in control (26.7% plain Levamisole baits vs. 83.3% untreated baits, P = 0.002) even afterplain Levamisole was no longer present in the baits (40.0% vs. 86.6% untreated baits, treat-ment and control respectively, P = 0.007). Foxes that ate Levamisole resinate baits, also atefewer baits than those in control (50.0% Levamisole resinate baits vs. 83.3% untreated baits,P = 0.043) but then resumed consumption when baits no longer contained the Levamisoleresinate (73.3% vs. 86.6% untreated baits, treatment and control respectively, P = 0.329).Thus, foxes that failed to detect the plain Levamisole in baits acquired CTA to the bait. Con-trary to our expectations, foxes detected the Levamisole resinate, associated illness withit and so resumed eating baits as soon as the resinate was withdrawn. Additionally, in thecontrol, where foxes were familiar with untreated ?safe? baits, we repeated the treatmentwith Levamisole resinate baits to test latent inhibition (decrement in conditioning to astimulus as a result of its prior exposure). We found that treated bait consumption did notdecrease as before, during a similar number of days (76.6% Levamisole resinate baits vs.83.3% untreated baits, P = 0.631), suggesting that latent inhibition prevented developmentof CTA within our experimental time period. CTA induced among grey foxes that consumeplain Levamisole baits might spare them from being poisoned in attempts to control otherspecies of predators.