POSITIONAL BEHAVIOR IN MOUSTACHED TAMARIN MONKEYS - EFFECTS OF HABITAT ON LOCOMOTOR VARIABILITY AND LOCOMOTOR STABILITY

Knowledge of the positional behavior of living primates offers signifi cant insight into patterns of habitat utilization, foraging strategies , and locomotor adaptations in fossil primates. Although it is general ly assumed that locomotor patterns are strongly constrained by anatomy , few studies have addressed the question of locomotor plasticity and the degree to which patterns of positional behavior may vary within th e same species. In this paper, we provide quantitative data on positio nal behavior and substrate preference in adult moustached tamarins (Sa guinus mystax) inhabiting two structurally distinct forest types in no rtheastern Peru. Despite major between-site differences in forest stru cture, tree density, liana density, and the extent of the continuous c anopy, overall patterns of positional behavior were virtually identica l. At the Padre Isla Field site, quadrupedal progression (55.7%), clim bing (5.7%) and leaping (24.8%) accounted for 86.2% of travel. At the Rio Blanco site, these locomotor behaviors (quadrupedal progression, 5 1.6%; climbing, 10.8%; and leaping, 30.9%) accounted for 93% of travel . Patterns of support preference were more variable, however, and appe ared to reflect site-specific differences in forest architecture. The results of this study indicate that both anatomy and local habitat pla y an important role in directing patterns of positional behavior in mo ustached tamarins. We argue, however, that locomotor anatomy acts to c onstrain the efficiency of locomotor choices and that even in forests of different canopy structure and tree density, tamarins negotiate pre ferred substrates using consistent patterns of positional behavior. Co mparisons with other taxa indicate that several species of arboreal pr imates are similarly characterized by limited between-site variability in positional behavior.