Foraging and inter‐individual distances of bearded capuchin monkeys

Abstract

Extractive foraging is a skill young capuchin monkeys learn over time. A key unknown is whether unskilled individuals occupy spatial positions that increase their opportunities to learn. We observed the spatial positions of individuals in a group of capuchin monkeys in Northeastern Brazil. To improve our understanding of the relationship between learning by young capuchin monkeys and inter-individual distance, we investigated the associations between the proximity of individuals and their age, activity, and proficiency at extractive foraging. To do this, we used one form of extractive foraging, opening palm nuts, as an index of proficiency at all types of extractive foraging. Our results indicate that, in the subset of the data where dyads consisted of one proficient individual and a partner with any level of proficiency, the distance between individuals was predicted by their foraging activity (i.e., extractive foraging, other foraging, or not foraging). In those dyads, the proficiency of the partner did not significantly improve prediction of inter-individual distances, indicating that spatial proximity of proficient individuals to others does not function primarily to increase opportunities for unskilled individuals to observe extractive foraging. Dyads in which both individuals were engaged in similar foraging activities (e.g., both "extractive foraging") exhibited the shortest inter-individual distances. Proximity between individuals engaged in similar foraging activities may result from the spatial distribution of resources or from social learning mechanisms, such as local or stimulus enhancement.

Ontogeny and sex differences in object manipulation and probe tool use by wild tufted capuchin monkeys (Sapajus libidinosus)

“…It allows youngsters to come closer and observe the objects used as tools, manipulate them, and eventually scrounge for food leftovers-a potential reinforcer in the learning process (Ottoni et al, 2005). However, a recent study on interindividual distances between capuchins performing extractive foraging (including stone tool use for palm nut-cracking) did not find a correlation between proficient individuals and skilled versus unskilled partners' distance, as a measure of opportunity for observation of the activity (Howard et al, 2018). The authors, however, did not specifically analysed stone tool use and they point that nut cracking in their study group is a very conspicuous activity, and that close visual observation may not be so important for observation learning of this behavior, as it could be for more cryptic foraging activities.…”

Emissão de vocalizações sirena por infantes de macacos-prego (<i>Sapajus libidinosus</i>)

“…A população de Sapajus libidinosus estudada aqui não apresenta dinâmica de fissão-fusão (Izar et al 2012). No entanto, os membros do grupo se distanciam durante o forrageio, cerca de vinte metros em média entre cada díade (Howard et al, 2018), de modo que alguns indivíduos, por exemplo aqueles na periferia do grupo, podem ficar sem contato visual com outros por um longo período de tempo (observação pessoal). Mesmo sem a fissão em subgrupos, machos e fêmeas, jovens e adultos já foram observados emitindo displays de reencontro, com emissão de sirena (ver Figura 1a) e sem, depois de permanecerem um período sem contato visual com os indivíduos que eles reencontraram (observação pessoal, Marcos Fonseca de Oliveira, com.…”