Factors Influencing Positional Behavior and Habitat Use of Sympatric Macaques in the Limestone Habitat of Nonggang, China.

Information on the positional behavior and habitat use of primates can help elucidate relationships among species' morphology, behavior, and environment, and contribute to our understanding of species' behavioral and ecological adaptations. Limestone habitats provide a unique and challenging habitat for primates, but there have been few detailed studies of the genus Macaca in such habitats, making a comparative understanding of extant limestone primates' behavioral adaptations incomplete. We collected data on positional behavior and habitat use by sympatric Assamese macaques ( Macaca assamensis) and rhesus macaques ( M. mulatta) in limestone habitat at Nonggang Nature Reserve, southwestern Guangxi, China, and examined the effects of morphological and ecological factors on positional behavior and habitat use. Our results indicate interspecific differences in positional behavior, showing different preferences for locomotor modes and substrates. Rhesus macaques tended to walk horizontally, whereas Assamese macaques more often climbed vertically. Rhesus macaques used smaller substrates (twigs) more frequently than did Assamese macaques. Time spent in different zones of limestone hills and forest strata also varied significantly between the two macaques. Assamese macaques most often used cliff faces, and tended to be terrestrial. Rhesus macaques were most likely to stay low on the hillsides, and spent most of their time in the lower strata of trees. These differences in positional behavior and habitat use are linked to differences in limb length and body size in the two species, and may be explained by the spatial distribution of preferred foods and structure of the forest in different areas of the limestone hills. [ABSTRACT FROM AUTHOR]