Herein lies one of the many fights between the dominant leader male of the “D” group, Demon, and his predecessor turned “grandpa”, Devil. The geladas (Theropithecus gelada) of the Simien Mountains in Ethiopia typically live in one-male unit groups, however, the dominant male occasionally allows a predecessor to stay on or a follower to tag along with the group (Synder-Mackler et al., 2012). But they still get into their fair share of skirmishes as seen here.

 [Photo and caption by Caitlin Hawley]

Synder-Mackler, N., Beehner, J.C., Bergman, T.J. (2012). Defining higher levels in the multilevel socieites of geladas (Theropithecus gelada). International Journal of Primatology. 33, 1054-1068.