Resource partitioning in sympatric langurs and macaques in tropical rainforests of the central Western Ghats, south India

Abstract

In a competitive sympatric association, coexisting species may try to reduce interspecific interactions as well as competition for similar resources by several ecological and behavioral practices. We studied resource utilization of three sympatric primate species namely, lion-tailed macaques (Macaca silenus), bonnet macaques (M. radiata) and Hanuman langurs (Semnopithecus entellus) in a tropical rainforest of the central Western Ghats, south India. We studied resource use, tree-height use, foraging height, substrate use when consuming animal prey and interspecific interactions. The results revealed that across the year, there was very limited niche overlap in diet between each species-pair. Each primate species largely depended on different plant species or different plant parts and phenophases from shared plant species. Primate species used different heights for foraging, and the two macaque species searched different substrates when foraging on animal prey. We also recorded season-wise resource abundance for the resources shared by these three primate species. While there was low dietary overlap during the dry season (a period of relatively low resource abundance), there was high dietary overlap between the two macaque species during the wet season (a period of high resource abundance for the shared resources). We observed only a few interspecific interactions. None of these were agonistic, even during the period of high niche overlap. This suggests that the sympatric primate species in this region are characterized by little or no contest competition. Unlike in some other regions of the Western Ghats, the lack of interspecific feeding competition appears to allow these primates, especially the macaques, to remain sympatric year-round.

Canopy utilization pattern of Western Hoolock Gibbon Hoolock Hoolock (Mammalia: Primates: Hylobatidae) in the Inner-line Reserve Forest of Barak Valley, Assam, India

“…In a competitive sympatric association, coexisting species may try to reduce interspecific interactions as well as competition for similar resources by several ecological and behavioral practices. Primate species used different heights for foraging, and the two macaque species searched different substrates when foraging on animal prey (Singh et al 2011). Identical vertical stratification, niche breadth and overlap among Rhesus Monkey, Capped Langur and the Hoolock Gibbon have been observed during the present study, wherein it has been observed that Rhesus Monkey used a lower niche and the Hoolock Gibbon prefer a niche that occupies the middle canopy, whereas the capped langur explored both the middle and upper niches.…”

Diet and Dietary-Niche Breadth of Diurnal Rain Forest Primates in the Central Western Ghats, India

“…In order to get a better understanding of the dietary diversity of these primates, we selected a region of the Western Ghats where lion-tailed macaques, bonnet macaques and Hanuman langurs are sympatric in the rain forests. In an earlier study [Singh et al, 2011], we reported that, in this region of the Western Ghats, the food niche overlap between the three primate species over the year was very small, except between bonnet macaques and lion-tailed macaques for a few months when resources were abundant. Since the availability of leaves is much higher than that of fruits, we expected that the primarily folivorous langurs would use a larger number of resources than the primarily frugivorous macaques.…”

“…In other words, all the primate species are mostly dependent on those plant species which are abundantly available in that region. The monthly productivity sampling denoted the presence of different resource parts of those major plant species [Singh et al, 2011]. Although some of the resources are very seasonal (like fruits of Garcinia gummigutta in the wet season or Holigarna grahamii in the dry season), the consumption frequency of those resources was very high.…”

Folivory as a Constraint on Social Behaviour of Langurs in South India

“…The major plant species and their parts used by Hanuman langurs are given in table 1 . Fruiting trees were abundant in this area [Singh et al, 2011]. The present study group occupied an area around Gerusoppa KPC quarters.…”

“…The study area is lowaltitude degraded coastal evergreen rain forest in the Western Ghats of north Karnataka in Uttara Kannada District. The forest comprises mainly Dipterocarpus-Holigarna-Persia species with an average altitude of 650 m [Singh et al, 2011] with an average annual precipitation of 4,200 mm and a relatively high humidity of 95%. The major plant species and their parts used by Hanuman langurs are given in table 1 .…”