Maternal grouping as a defense against infanticide by males: evidence from field playback experiments on African lions

Female lions roar in order to stay in contact with their pridemates and to defend their territory against other prides. In doing so, however, they risk attracting the attention of potentially infanticidal nonresident males. We used playback experiments to demonstrate that nonresident males are indeed specifically attracted to female roars, approaching the roars of female, but not male, conspecifics. However, there was also evidence that males adjust their behavior according to the probability that they might execute a successful takeover. Alien male lions were more reluctant to approach playbacks of three females roaring than of a single female roaring; single males were more reluctant than pairs to approach female roars; and old males were more reluctant than younger males to approach female roars. Previous observational studies have shown that female lions living in groups are more successful than singletons at defending their cubs in direct interactions with potentially infanticidal males. Our results suggest that maternal groups may also, by roaring in chorus, minimize the chances that these encounters occur at all.