Mouse pups discriminate food gnawed by conspecifics

Eighteen- and 24-day-old albino mice, the former experiencing their first direct contact with solid food, were offered a set of food pellets, some of which had been gnawed by adult conspecifics of various conditions. No adult was present during the test. The subjects of both ages clearly preferred intact pellets over pellets gnawed by mice, although familiarity with the donor of residual cues had a positive effect on Day 24 (Experiment 1). When pellets were treated with garlic extract, an initially aversive compound, the younger subjects showed initial preference for pellets gnawed by the dam over intact pellets, although avoidance of gnawed pellets was a main result again (Experiment 2). Tendency of the mouse to avoid crowding near a feeding point seems a likely explanation of this residual-cue avoidance, which also seems inversely related to neophobia. A behavioural difference from the rat is suggested.