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

Abstract

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.

First report of food sharing among nicobar long-tailed macaques

“…Here we argue that the presence of food sharing in our study population might be due the combination of two particular features that characterize the Nicobar macaque population: 1) the presence of monopolizable food sources that can be accessed by only a limited number of individuals, namely those macaques who are particularly skilful in breaking a coconut open; and 2) the ability to use tools and manipulate objects (Mazumder and Kaburu, 2020). Coconuts, like many other cultivated fruits, tend to have a higher nutritional value compared to many wild plants, and, for this reason, they tend to be preferred food items for wild animals (Siex and Struhsaker, 1999;Pal et al, 2017a;Das et al, 2020). However, accessing the coconut meat can be challenging and, among Nicobar macaques, only a few individuals are often able to open coconuts using complex manipulative techniques (Pal et al, 2017b;Mazumder and Kaburu, 2020).…”

The art of snacking: Innovative food extraction in a synanthropic species is associated with food exposure and food categorization

“…An additional variable that appears to play a decisive role in the acquisition and development of extractive foraging behavior is exposure (to demonstrators and to elements associated with the foraging task), sometimes at a critical developmental phase (Inoue-Nakamura & Matsuzawa, 1997; Neadle et al, 2020). However, despite its broad role in individual/social learning (see Das et al, 2020; Hoppitt & Laland, 2013; Kummer & Goodall, 1985) and alternately, in catalyzing individual reinnovation of latent solutions (Reindl et al, 2018), the role of prior/extended exposure in execution of food extraction tasks has been largely biased towards technical (i.e. tool-use assisted) extractive foraging (e.g.…”