Stone tools differences across three capuchin monkey populations: food’s physical properties, ecology, and culture

Abstract

Robust capuchin monkeys (Sapajus) are known for processing mechanically challenging foods, having morphological adaptations to do so. However, several populations go beyond body limitations by using stone tools to expand their food range. Those populations use stones in a variety of ways, goals, and with different frequencies. Stone tool size correlates with the food’s resistance within some populations. However, we have no detailed comparisons to identify if this correlation is the same across populations. This study described and compared stone raw material availability, food’s physical properties (hardness and elasticity), and stone tool weight in three populations of bearded capuchin monkeys (Sapajus libidinosus), including a newly described site (Chapada dos Veadeiros National Park, CVNP). The differences we observed regarding stone tool weight selection among sites were not correlated to the food’s physical properties we analyzed. Lithic resource availability could partly explain some differences in the stone tools used. However, the tool weight differences are larger than the raw material variance across sites, meaning some distinctions are possible behavioral traditions, such as the same fruit (Hymenaea) being processed with bigger than needed tools in CVNP than in the other two sites. Capuchin monkey behavioral variability in stone tool use can be caused by several interacting factors, from ecological to cultural.

Hand preference in wild crab‐eating capuchin monkeys (Sapajus libidinosus) in the coastal area of Northest Brazil

“…Tufted capuchin monkeys ( Sapajus spp.) are an ideal species to study hand preference, since they are extractive foragers that frequently manipulate objects (Fragaszy et al, 2004; Truppa et al, 2018) and are known to use different tools to access diverse foods, including encapsulated fruits (Falótico et al, 2022; Mannu & Ottoni, 2009; Ottoni & Izar, 2008). The capuchins living in the mangrove forests along the Preguiças river catch crabs and crack open their exoskeletons with and without tools providing a novel scenario to study hand preference in this species.…”

Mapping nut‐cracking in a new population of wild capuchin monkeys (Sapajus libidinosus) at Ubajara National Park, Brazil

“…To sample the availability of stones in the area, we did a 50 × 50 cm subplot in the SW corner of each plot, measuring the quantity, dimensions, weight, and composition of every rock with a length of more than 3 cm. We applied the same sampling protocol to other sites in the scope of the CapCult project (Falótico et al, 2022).…”

“…For this comparison, we used populations that had more than 5 days of surveys or longer studies (Chalk et al, 2015;Coutinho, 2021;De Moraes et al, 2014;Falótico et al, 2018Falótico et al, , 2022Ferraz et al, 2003;Mannu & Ottoni, 2009;L. P. C. dos Santos, 2015;Visalberghi et al, 2008Visalberghi et al, , 2016.…”

“…The ongoing analysis of the video-recorded nut-cracking events will give us more information about the efficiency of babaçu nut-cracking by this population, and future experimental approaches exploring tool selection might also help to clarify the factors affecting stone choice in this population. Another factor, not exclusive, that could influence the stone choice could be a cultural bias to the smaller stone size used for the most frequent food resource exploited with it, as observed in the other direction (bigger stone tools to process softer resources) in the S. libidinosus of CVNP (Falótico et al, 2022).…”

“…Robust capuchin monkeys are proficient tool users in captivity and in the wild Falótico et al, 2018;Fragaszy et al, 2004;Westergaard & Fragaszy, 1987;Westergaard, 1992). For instance, numerous wild populations of bearded capuchins (Sapajus libidinosus), mostly in savannah environments (Cerrado and Caatinga), use tools predominantly to crack open encased foods, such as nuts and seeds (Falótico et al, 2018(Falótico et al, , 2022Falótico, 2022;Mendes et al, 2015;Visalberghi et al, 2015). The most common resources are palm nuts, which have been observed to be cracked open in several populations, such as Fazenda Boa Vista (FBV, Spagnoletti et al, 2011), Chapada dos Veadeiros (CVNP, Falótico et al, 2022), both in Cerrado, Serra das Confusões (SCoNP, Falótico et al, 2018), in a Cerrado-Caatinga ecotone, and Serra Talhada (Moraes et al, 2014; Figure 1), in F I G U R E 1 Map showing the locations of the six compared medium and long-term study sites that had data on stone tool use split by resource: Ubajara (UNP), Serra da Capivara (SCaNP), Serra das Confusões (SCoNP), Chapada dos Veadeiros (CVNP), Fazenda Boa Vista (FBV), and Serra Talhada (ST).…”