Correspondence Among Locomotor Profiles, Daily Stride Cycles, and Femoral Bone Robusticity in Taï Forest...

This study explores linkages between daily locomotor cycles to structural and material biomechanical variables in four sympatric West African cercopithecid species. While functional studies of primate postcrania typically rely on locomotor and activity profiles to create a context for biomechanical interpretation, two variables not typically included in such studies are stride counts and rest intervals. The former provide information on cumulative daily loads, while the latter have been shown to have positive osteogenic effects.

Daily stride cycle counts in four adult females representing four sympatric cercopithecid species were collected over 30-day periods. Individuals of the western red colobus (Piliocolobus badius), black and white (king or pied) colobus (Colobus polykomos), Diana monkey (Cercopithecus diana), and sooty mangabey (Cercocebus atys) were followed in the Taï Forest, Côte d'Ivoire. We also recruited existing data on activity patterns to provide a qualitative assessment of the amount of daily rest among these species. We utilized existing data on femoral mechanical properties from individuals within these populations to discern whether the number of daily locomotor cycles corresponded with indices of bone robusticity.

Differences in daily stride counts distinguish the four individuals, with higher stride counts characterizing the representatives of the two cercopithecine species. We do not observe a correspondence between stride counts and measures of long bone robusticity. Cumulative daily loads do not correspond to stronger or denser bones.

The inclusion of information on rest duration and spacing may clarify functional linkages between locomotor behavior and skeletal mechanical properties.