A CASE OF INFANTICIDE IN A RECENTLY FOUND GELADA POPULATION IN ARSI, ETHIOPIA

There have been no reports of infanticide in wild gelada baboons and i t has been argued that infanticide is not necessary in geladas, since the birth interval of female gelada can be shortened after takeover of a unit by a new leader male without infanticide. However, we observed an instance of infanticide in a newly-found wild gelada population in the Arsi Region of Ethiopia. After a leader male of the unit was seve rely wounded by a leopard attack, he was quite weakened. The second ma le of the unit, a young adult male, became the leader of,:he unit thre e weeks later, but the former leader continued to stay in the unit as a second male. After a week, two other adult males joined the unit whi ch, therefore, came to include four adult males. The infanticide took place nine days later. The perpetrator was one of the immigrant males and he showed great interest in the mother of the unweaned victim infa nt. Although the perpetrator copulated with her after the infanticide, the usurper was found to own all three adult females after two weeks following the infanticide; i.e. the perpetrator could not own any fema le. The wounded former leader showed conspicuous protective behavior t owards the victim's mother and the dead infant. One possible explanati on for the occurrence of infanticide in this population of geladas is as follows. Gelada males in this area may be able to join units more e asily to form multi-male units but then have shorter tenure in the uni ts. Facing the unstable condition of units, they may sometimes engage in infanticide to increase their breeding opportunities, even before b ecoming a leader.