A quantitative comparison of the behaviour of a wild and a caged baboon group

Abstract

1. (1) A wild and a caged baboon population were compared on the basis of roughly 300 hr of observation on each population. The effect of different population compositions is discussed. 2. (2) Comparison was of the number and type of interactions seen between adult males, adult females and weaned juveniles and of the incidence of twenty common behaviour patterns in these interactions. 3. (3) Interactions were nearly four times more frequent in the cage than in the wild. 4. (4) Approach-retreat (as opposed to friendly) interactions were more common in the cage. This increase was not even throughout all eight classes of interactions for which comparison was available, but was especially marked in female-female interactions. 5. (5) The structure of approach-retreat interactions in the two populations did not differ much within each interaction class. Most differences occurred in those patterns which are also included in play behaviour and were shown elsewhere to be little correlated with rank order in the caged group. 6. (6) Friendly behaviour showed more differences, many of which were consistent with a higher level of stress in the caged group. 7. (7) Wild adult males had no detectable hierarchy and frequently moved between troops. Their approach-retreat behaviour was similar to that of wild adult females amongst themselves; their friendly behaviour differed in a way that suggested a higher degree of tension than between females. The role of the males in the group in forming a highly co-operative policing system is described. 8. (8) Results are discussed in terms of the relation between hierarchy formation and environmental stress.