DO PREDATORS AVOID GROUPS OF APOSEMATIC PREY - AN EXPERIMENTAL TEST

This study investigated the widely held idea that predators are disinclined to attack groups of aposematic prey. There were four experimental situations. Great tits, Parus major, were presented with either grouped or solitary individuals of either larvae of the European pine sawfly, Neodiprion sertifer, or larvae of the European swallowtail, Papilio machaon. Sawfly larvae are naturally gregarious and the swallowtail larvae solitary. The sawfly larvae were attacked, killed and eaten more frequently than swallowtail larvae. The attack frequency was not independent of whether prey was grouped or solitary but groups of sawflies were attacked less than solitary individuals, whereas groups of swallowtails were attacked more than solitary individuals. The results imply that a high initial cost of group living may be reduced through the evolution of communal defence or display. © 1990 The Association for the Study of Animal Behaviour.