Spatial patterns within gelada monkey one male units at Guassa, Ethiopia

Abstract

I used repeated, accurate positional data, collected between October 2013 and January 2014, on all adult members of nine gelada monkey One-Male Units (OMUs) living at Guassa, Ethiopia to investigate the consequences of a modular, multilevel social organization for the spatial associations of individuals. The results indicate that distances between individuals within OMUs did not change with increasing group size, such that larger OMUs necessarily occupied more space. Unit males were significantly more likely to be in the vanguard. The group geometry of OMUs was distinctive in that all groups, being stretched along the axis of travel, were best described as files. The extent of conformity to a file was best explained by activity and travel speed, rather than by demographic or ecological factors. These results are interpreted in the context of the optimization of foraging by OMU members living in the immediate proximity of other OMUs.