Failure of food-aversion conditioning to suppress predatory attack of the grasshopper mouse, Onychomys leucogaster

Abstract

Food-aversion learning has suppressed predatory attacks toward live prey in several but not all species tested. The purpose here is to show that, in the case of the carnivorous grasshopper mouse, stimuli associated with the movement of the prey contribute to the failure of conditioned taste aversion to suppress an attack. Mice were given intraperitoneal injections of LiCl immediately after an attack or feeding. Mice developed some aversion to the live prey, but not enough to suppress an attack. When the experiment was repeated using dead prey, an attack was suppressed in the majority of the mice. When the suppression of attack toward live and dead prey was measured using a noxious chemical coating as a deterrent, again attacks were inhibited more successfully with dead prey than with live prey. These results are consistent with the notions that the mouse's response to the prey's movements overrides the aversion-induced inhibition of killing and that eating and killing are controlled by separate mechanisms.