Ranging Behavior and Resource Use by Lion-Tailed Macaques (Macaca silenus) in Selectively Logged Forests

Abstract

Physical and ecological factors such as season, rainfall, food availability, number of plant species eaten, intergroup encounters, and degree of terrestriality influence the daily path length (DPL) and home range use of animals. We examined whether these factors influenced DPL and home range use in a group of endemic lion-tailed macaques (Macaca silenus) in the selectively logged forests of Sirsi-Honnavara in the central Western Ghats Mountains of south India. We predicted that monthly rainfall, fruit tree density, number of plant species eaten, intergroup encounters, and terrestriality would correlate with DPL, and fruit tree density, overall tree density, and richness of fruiting tree species would correlate with home range use. We collected data on feeding ecology from scan sampling, and DPL and home range use by recording the geo-coordinates of the focal group with a handheld GPS during daily follows. We obtained 1230 h of observations over 24 mo between 2008 and 2011. We collected data on the density of food species and of all trees using the point-centered quarter method in 1-ha grid cells overlaid on the home range of the study group. Results showed that the mean monthly DPL correlated positively with the number of trees fruiting in a month and negatively with rainfall. Overall tree density and fruit tree density correlated positively with habitat use. These findings support the hypothesis that primary food resources are a major determinant of primate ranging patterns. Our results are also important for lion-tailed macaque conservation, in light of the pressure the habitat has been facing. We propose conservation action to include the important food species of lion-tailed macaques for habitat restoration by the local forest department.