The Conservative Nature of Primate Positional Behavior: Testing for Locomotor and Postural Variation in Colobus vellerosus and Cercopithecus campbelli lowei at Boabeng-Fiema Monkey Sanctuary, Ghana

Several recent field studies have shown that primate posture and locomotion exhibit minimal intraspecific variation. Between January and November 2009, I collected data on positional behavior and habitat use via three-minute instantaneous focal observation of the ursine colobus (Colobus vellerosus) and Lowe’s monkey (Cercopithecus campbelli lowei) at the Boabeng-Fiema Monkey Sanctuary (BFMS), Ghana. I sampled quantitative ecological data on canopy density, understory density, tree size and average number of large trees in two areas of forest characterized by differing degrees of anthropogenic disturbance. Using Row x Column statistical comparisons (G-tests, Fisher Exact Tests), I tested for significant intraspecific variation in postural and locomotor profiles for females of each species living in these forest areas. For both species, forest strata, support size, support orientation and postural profiles differed significantly between these forests. Locomotor profiles differed significantly between forests only for guenons. I argue that the mosaic nature of more disturbed forest at BFMS reduced the number of direct, upper canopy arboreal pathways and resulted in more frequent use of lower and thinner supports for both species. Intraspecific postural and locomotor contrasts between habitats are considered in the context of body mass support, balance, and diet. Colobus locomotor consistency may be a product of both their larger body size and leaping specializations of their postcrania. I also tested for significant sex-based differences in positional behavior for both species. While my male dataset was limited, significant differences in overall postural and locomotor profiles were evident. I argue that contrasting nutritional requirements, social roles, and body sizes between the sexes for both species underlie these contrasting positional behavior profiles. While statistical differences in postural (both guenons and colobus) and locomotor profiles (guenons) may be ecologically significant, the differences identified in this study pose little threat to established form-function associations in primates and support the notion that primate positional behavior is largely conserved across sexes and habitats.