WHICH ADULT MALE SAVANNA BABOONS FORM COALITIONS

We investigated the mechanism of alliance formation among adult male s avanna baboons by comparing the characteristics-of males that formed c oalitions frequently with males that never or seldom took part in coal itions. We observed three groups: two of Papio cynocephalus cynocephal us in Amboseli National park Kenya, and one of P. c. anubis in the vic inity of Gilgil, Kenya. We considered four hypotheses: (1) Males must be familiar with each other, (2) males must have an affinitive bond, ( 3) males must have move than average experience, and (4) the combined fighting ability of the coalition partners relative to the fighting ab ility of their opponent determines the likelihood that a coalition is formed. We conclude that relative fighting ability forms the key facto r in coalition formation. High-ranking males do not form coalitions of ten, since they hardly need them. Low-ranking males rarely form coalit ions, since they cannot form effective coalitions among themselves. Af finity (''friendship'') may play a role as an additional factor. The r elation of coalition formation with age and period of residence, which was found in several studies, can be explained largely by the correla tion between these parameters and fighting ability.