Social tactics of pigs in a competitive foraging task: the 'informed forager' paradigm

Studies of the social dynamics in foraging groups have focused primarily on birds, rodents and nonhuman primates. We extended the study of animal soci al tactics to the domestic pig, Sus scrofa, by using an experimental analog ue of natural foraging skills, the 'informed forager' paradigm. We investig ated the behaviour of 16 pigs foraging in pairs in an arena in which food h ad been hidden in one of eight monopolizable buckets. Before each pair tria l, one of the pigs, the 'informed' pig, was given privileged knowledge abou t the location of the food during a solitary search trial. The 'noninformed ' pig was naive about the location of the food during pair trials, but heav ier than its informed partner and thus able to displace the latter from the baited bucket. By first focusing on the informed pigs' behaviour, we show that pigs are able to remember and relocate the food site. They found the f ood in relocation trials, using fewer bucket investigations than expected o f a random searcher. Second, by focusing on the noninformed pigs, we show t hat pigs are able to exploit the knowledge of others by following them to a food source. They investigated more buckets immediately after their inform ed partners significantly more often than expected by chance and required f ewer bucket investigations to find the food in pair trials than expected fr om a random searcher, but not in solitary search trials. We discuss these l atter findings with reference to social foraging tactics. (C) 2000 The Asso ciation for the Study of Animal Behaviour.