Vocal recognition in the spotted hyaena and its possible implications regarding the evolution of intelligence

Spotted hyaenas, Crocuta crocuta, are gregarious carnivores whose social li ves share much in common with those of cercopithecine primates. We conducte d playback experiments to determine whether free-living hyaenas are capable of identifying individual conspecifics on the basis of their long-distance vocalization, the 'whoop'. When prerecorded cub whoops were played to moth ers and other breeding females (controls), mothers responded significantly more vigorously to whoops of their own cubs than did controls. We also test ed the hypothesis that specific vocal recognition abilities are based on ki nship in this species. Listeners that were related to the whooping cub resp onded more vigorously to recorded vocalizations than did unrelated individu als, with response intensity in some cases increasing directly with the siz e of the coefficient of relatedness (r). Our final goal was to determine wh ether control animals in these experiments can recognize third-party social relationships among other group members, an ability demonstrated by vervet monkeys, Cercopithecus aethiops, in similar playback experiments conducted by earlier investigators. In contrast to vervets, control females in the p resent experiments were no more likely to look at the mother of the whoopin g cub than at other control females after playback. This suggests that hyae nas may accomplish many of the same social feats as do vervets without poss essing the ability to recognize third-party relationships. If confirmed in other domains of hyaena social life, our findings have important implicatio ns regarding selection pressures favouring the evolution of intelligence. ( C) 1999 The Association for the Study Animal Behaviour.