Use of an embedded fruit by Nicobar Long-tailed Macaque Macaca fascicularis umbrosus: II. Demographic influences on choices of coconuts Cocos nucifera and pattern of forays to palm plantations

摘要

Adaptive pressures of human-induced rapid environmental changes and insular ecological conditions have led to behavioral innovations among behaviorally flexible nonhuman primates. Documenting long-term responses of threatened populations is vital for our understanding of species and location-specific adaptive capacities under fluctuating equilibrium. The Nicobar Long-tailed Macaque Macaca fascicularis umbrosus , an insular sub-species uses coconuts Cocos nucifera , an embedded cultivar as a food resource and is speculated to have enhanced its dependence as a result of anthropogenic and environmental alterations. We explored demographic patterns of use and abandonment of different phenophases of fresh coconuts. To study crop foraging strategies, we recorded daily entry and duration of forays into coconut plantations. We divided age-classes into early juvenile (13–36 months), late juvenile (37–72 months), and adults (72 months) and classified phenophase of coconuts into six types. Consistent with the theory of life history strategies, late juveniles were found to use a greater number of coconuts, which was considerably higher in an urban troop but marginally higher in a forest-plantation dwelling group. Except in late juveniles, males consumed a higher number of coconuts than females in the remaining age-classes. Owing to developmental constraints, juveniles of both types used higher proportion of immature coconuts though adults showed equitable distribution across phenophases. Pattern of entries to plantations and duration of forays were uniform through the day in the urban troop but modulatory in the forest-plantation group, perhaps due to frequent and hostile human interferences. Observations corroborating adaptations to anthropogenic disturbances are described. Author Biographies Sayantan Das?manages the Nicobar Project of the Biopsychology laboratory at the University of Mysore. He is interested in behavior, ecology and environmental conservation.