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Knowledge of the feeding habits of primate species is important for an understanding of their natural history and ecological interactions between their groups, and their interactions with their environments. Capuchin monkeys (Sapajus spp.) present significant diet flexibility and are a good model for investigating diet diversity between species. We undertook a systematic literature review of publications on the diet of free-living Sapajus spp. groups by using the Web of Science platform. We performed scientometric analyses of the objectives and hypotheses of the reviewed works, identified knowledge gaps, and evaluated the composition of each group's diet. Our results indicate geographic and taxonomic biases among the 59 published studies that we examined. The studies were focused on Sapajus nigritus, Sapajus libidinosus, and Sapajus apella, and undertaken in long-term study sites. Foraging and behavioral aspects of how food is processed were recurring themes. Capuchin monkeys increase their consumption of anthropogenic food according to its supply. Despite the similar objectives of these studies, standardized data collection protocols were not employed. Although Sapajus spp. are widely distributed and are used for cognitive studies, basic aspects of their natural history, such as their diet, remain unknown. We emphasize the importance of undertaking studies on this genus to fill the identified knowledge gaps, and propose that investigations should be carried out on the effects of dietary changes on individuals and groups. We stress that, as the Neotropical region is one of those most affected by anthropogenic impacts, opportunities to study these primates in their natural environments are diminishing daily.

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Many white-faced capuchin monkey dyads in Lomas Barbudal, Costa Rica, practise idiosyncratic interaction sequences that are not part of the species-typical behavioural repertoire. These interactions often include uncomfortable or risky elements. These interactions exhibit the following characteristics commonly featured in definitions of rituals in humans: (i) they involve an unusual intensity of focus on the partner, (ii) the behaviours have no immediate utilitarian purpose, (iii) they sometimes involve 'sacred objects', (iv) the distribution of these behaviours suggests that they are invented and spread via social learning, and (v) many behaviours in these rituals are repurposed from other behavioural domains (e.g. extractive foraging). However, in contrast with some definitions of ritual, capuchin rituals are not overly rigid in their form, nor do the sequences have specific opening and closing actions. In our 9260 h of observation, ritual performance rate was uncorrelated with amount of time dyads spent in proximity but (modestly) associated with higher relationship quality and rate of coalition formation across dyads. Our results suggest that capuchin rituals serve a bond-testing rather than a bond-strengthening function. Ritual interactions are exclusively dyadic, and between-dyad consistency in form is low, casting doubt on the alternative hypothesis that they enhance group-wide solidarity. This article is part of the theme issue 'Ritual renaissance: new insights into the most human of behaviours'.

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Tropical forests have a high diversity of tree species which have very low densities and vary across time in their seasons of peak fruiting and maturation rates. As evidence of the ability of primates to track or anticipate changes in fruit production at individual trees, researchers have used the increased speed of primate groups toward more rewarding food patches. We analyzed the speed of approach to natural trees of wild capuchin monkeys under the effect of scramble competition, after excluding any plausible visual, olfactory and auditory cues. We conducted all-day group follows of three habituated capuchin groups at Iguazú National Park, Argentina, collecting data on ranging behavior and patterns of visits to fruit trees in relation with their location and fruit availability. Travel speed varied according to the expected reward at a feeding tree, increasing as rewards increased from low values, but decreasing again at very high values. Also, travel speed varied with time of day, decreasing from the time of first activity as the monkeys became less hungry, and increasing again toward late afternoon. Measures of unripe fruit cover did not explain variation in travel speed at any distance from a focal tree. Our data imply that, after excluding sensory cues, capuchins appear to anticipate time-varying ripe fruit quantity of natural resources, suggesting that they use memory of tree location and anticipation of fruit maturation. We also confirm that speed is a good measure about expectations of resources, as has been shown in previous studies.

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Most mammals live in social groups in which members form differentiated social relationships. Individuals may vary in their degree of sociality, and this variation can be associated with differential fitness. In some species, for example, female sociality has a positive effect on infant survival. However, investigations of such cases are still rare, and no previous study has considered how male infanticide might constrain effects of female sociality on infant survival. Infanticide is part of the male reproductive strategy in many mammals, and it has the potential to override, or even reverse, effects of female reproductive strategies, including sociality. Therefore, we investigated the relationships between female sociality, offspring survival, and infanticide risk in wild white-faced capuchin monkeys using long-term data from Santa Rosa, Costa Rica. Female capuchins formed differentiated bonds, and bond strength was predicted by kin relationship, rank difference, and the presence of female infants. Most females formed stable bonds with their top social partners, although bond stability varied considerably. Offspring of highly social females, who were often high-ranking females, exhibited higher survivorship during stable periods compared with offspring of less social females. However, offspring of highly social females were more likely to die or disappear during periods of alpha male replacements, probably because new alpha males are central to the group, and therefore more likely to target the infants of highly social, central females. This study shows that female sociality in mammals can have negative fitness consequences that are imposed by male behavior.

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The effects of culture on individual cognition have become a core issue among cultural primatologists. Field studies with wild populations provide evidence on the role of social cues in the ontogeny of tool use in non-human primates, and on the transmission of such behaviours over generations through socially biased learning. Recent experimental studies have shown that cultural knowledge may influence problem solving in wild populations of chimpanzees. Here, we present the results from a field experiment comparing the performance of bearded capuchin monkeys (Sapajus libidinosus) from two wild savannah populations with distinct toolkits in a probing task. Only the population that already exhibited the customary use of probing tools succeeded in solving the new problem, suggesting that their cultural repertoire shaped their approach to the new task. Moreover, only this population, which uses stone tools in a broader range of contexts, tried to use them to solve the problem. Social interactions can affect the formation of learning sets and they affect the performance of the monkeys in problem solving. We suggest that behavioural traditions affect the ways non-human primates solve novel foraging problems using tools.

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Wild capuchin monkeys (Sapajus libidinosus) at Serra da Capivara National Park, Brazil, regularly use stone tools to break open cashew nuts (Anacardium spp.). Here we examine 2 approaches used by the capuchins to position the kidney-shaped cashew nuts on an anvil before striking with a stone tool. Lateral positioning involves placing the nut on its flatter, more stable side, therefore requiring less attention from the monkey during placement. However, the less stable and never previously described arched position, in which the nut is balanced with its curved side uppermost, requires less force to crack the outer shell. We observed cashew nut cracking in a field experimental setting. Only 6 of 20 adults, of both sexes, were observed to deliberately place cashew nuts in an arched position, which may indicate that the technique requires time and experience to learn. We also found that use of the arched position with dry nuts, but not fresh, required, in 63% of the time, an initial processing to remove one of the cashew nut lobes, creating a more stable base for the arch. This relatively rare behaviour appears to have a complex ontogeny, but further studies are required to establish the extent to which social learning is involved.

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The behavioural repertoires and time budgets of 2 captive groups and 1 semi-free-ranging group of Cebus olivaceus were determined with the aim to assess the impact of the zoo environment on behaviour. The repertoires were qualitatively similar between groups and to those reported for wild troops, but the captive groups showed self-directed and stereotyped behaviours not reported in the wild. The differences in repertoires between groups were easily associated with the opportunity to interact directly with the visitors, with particularities of the enclosure and with the severity of confinement. Overall, females spent more time foraging than males in the 2 captive groups, and adults rested and watched more than subadults in all the groups. Time budgets were dominated by foraging, resting, movement and affiliative interactions, but their relative importance varied between groups, with foraging being especially prominent in the most confined group. The time budgets also varied qualitatively from those reported for wild troops. We conclude the species is behaviourally able to adjust to captivity, but the slight differences along the continuum from wild to semi-free to captive are suggestive of mild stress or social tension probably due to unstimulating environmental conditions, high visitor pressure and deviations from typical sex-age group composition.

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Cracking nuts with tools is a behavior documented in a small number of populations of tufted capuchins, mainly in semi-arid Caatinga and Caatinga-Cerrado transitional environments of northeastern Brazil. Only one of these populations inhabits the less arid Cerrado in Central Brazil, where environments are composed of a heterogeneous mosaic of fields, savannas and forest formations. We conducted surveys in 10 of 20 localities where nutcracking by capuchins was reported by the local inhabitants in the Cerrrado of Northern Goiás and Tocantins. Our purpose was to evaluate nutcracking sites (anvils and associated hammers and nuts) based on indirect evidence of extensive pounding of nuts and seeds. Nutcracking was confirmed at all 10 surveyed localities. A total of 270 sites were identified. Surveyed localities included areas that were ecologically similar to those where capuchins crack nuts in Caatinga, as well as less arid localities with more typical Cerrado habitat. Anvils and hammers were made of materials including quartz, limestone, sandstone and wood, and displayed a wider range of sizes (i.e., 60-3,750 g for hammers' weight) than reported at previously studied localities. Nuts of seven genera were found in association with anvils and hammers. We conclude that nutcracking by capuchins are not restricted to arid environments and argue that the occurrence and diversity of nutcracking tool sites result from complex interactions of environmental variables (e.g., availability of food and mineral resources, density of canopy cover) and social variables (e.g., spatial cohesiveness and tolerance among group members) that need to be examined through long-term research of habituated groups. Localities in the Cerrado of Northern Goiás and Tocantins vary considerable in the ecological conditions faced by wild groups, and therefore offer the opportunity to examine these interactions.

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The increase of ecotourism operations within Costa Rica during the last 20 yrs has brought more and more humans into close, direct contact with several wildlife species. One of these species is the white-faced capuchin (Cebus capucinos), highly gregarious, and with exposure over time, willing to come into close vicinity of humans and their developments. Such contact has its advantages and disadvantages for the ecotourism industry. We observed white-faced monkeys in order to assess the impact of human presence and development on monkey behavior, with a focus on aggressive, affiliative, and foraging behaviors in Curú Wildlife Refuge (CWR), located in Puntarenas, Costa Rica, and to ascertain the degree of over-habituation of capuchin popula- tions at CWR. Though there exists no discrete behavioral parameters that measure over-habituation, it can be defined as an extreme state of habituation in which non-human primates not only lose fear of humans, but also actively include humans in social interactions or treat them as a food resource. We used instantaneous focal animal and group scan sampling during 8 wks in March and April 2012. Two groups (approximately 20-30 individuals each) of capuchins were observed; the first near the tourist development at the Southwestern area of CWR, representing a habituated population that regularly foraged, rested, and groomed in the presence of humans. The second, was observed in the Northeastern area of CWR, did not visit the center of human activity and exhibited fear of humans. The habituated group exhibited significantly fewer instances of threatened behavior in response to human presence (p < 0.0001) than the non-habituated group, and spent significantly more time eating and foraging (p < 0.0001). While the habituated monkeys at CWR may not be over-habituated, they could become that way as development, especially ecotourism, increases. Over-habituation is a problem that affects capuchins in certain ecotourism sites in Costa Rica. It is critical that the consequences of habituation be studied more carefully, primarily in areas where ecotourism operations draw visitors to wildlife habitats.

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The increase of ecotourism operations within Costa Rica during the last 20yrs has brought more and more humans into close, direct contact with several wildlife species. One of these species is the white-faced capuchin (Cebus capucinus), highly gregarious, and with exposure over time, willing to come into close vicinity of humans and their developments. Such contact has its advantages and disadvantages for the ecotourism industry. We observed white-faced monkeys in order to assess the impact of human presence and development on monkey behavior, with a focus on aggressive, affiliative, and foraging behaviors in Curú Wildlife Refuge (CWR), located in Puntarenas, Costa Rica, and to ascertain the degree of over-habituation of capuchin populations at CWR. Though there exists no discrete behavioral parameters that measure over-habituation, it can be defined as an extreme state of habituation in which non-human primates not only lose fear of humans, but also actively include humans in social interactions or treat them as a food resource. We used instantaneous focal animal and group scan sampling during 8wks in March and April 2012. Two groups (approximately 20-30 individuals each) of capuchins were observed; the first near the tourist development at the Southwestern area of CWR, representing a habituated population that regularly foraged, rested, and groomed in the presence of humans. The second, was observed in the Northeastern area of CWR, did not visit the center of human activity and exhibited fear of humans. The habituated group exhibited significantly fewer instances of threatened behavior in response to human presence (p<0.0001) than the non-habituated group, and spent significantly more time eating and foraging (p<0.0001). While the habituated monkeys at CWR may not be over-habituated, they could become that way as development, especially ecotourism, increases. Over-habituation is a problem that affects capuchins in certain ecotourism sites in Costa Rica. It is critical that the consequences of habituation be studied more carefully, primarily in areas where ecotourism operations draw visitors to wildlife habitats. Rev. Biol. Trop. 62 (3): 909-918. Epub 2014 September 01.

El aumento de actividades ecoturísticas en Costa Rica durante los últimos 20 años ha ocasionado que más y más personas entren en contacto directo y cercano con varias especies de vida silvestre. Una de estas especies es el mono carablanca (Cebus capucinus), que es muy gregario y, al pasar el tiempo, tiende a acercarse a los humanos y sus instalaciones. Tal contacto tiene ventajas y desventajas para la industria del ecoturismo. Observamos monos carablanca con el fin de evaluar el impacto de la presencia humana y la infraestructura en el comportamiento de estos animales, enfocando los comportamientos de agresión, acicalamiento y forrajeo para determinar el grado de habituación excesiva de las poblaciones de monos capuchinos en el Refugio de Vida Silvestre Curú, Puntarenas, Costa Rica. Aunque no existen parámetros específicos de comportamiento para medir la habituación excesiva, se puede definir esta condición como un estado en que los primates no humanos no solamente pierdan su temor a los humanos, sino que también incluyen a las personas activamente en sus interacciones sociales o las consideran como una fuente de alimentación. Los monos carablanca fueron observados a través del muestreo instantáneo focal y por escaneo grupal durante ocho semanas de marzo y abril de 2012. Dos grupos (aproximadamente 20-30 individuos cada uno) fueron observados; uno cerca del desarrollo turístico en la parte suroeste del refugio, que representó una población habituada que de manera regular comía, descansaba y se acicalaba en presencia de humanos; el segundo grupo, que se observó en el noreste del refugio, no visitaba el centro de actividad humana y mostraba temor hacia los humanos. El grupo habituado mostró significativamente menos ocasiones de comportamiento amenazante ante la presencia humana (p<0.0001) y empleó más tiempo comiendo y buscando alimento (p<0.0001). Aunque el grupo de habituados en Curú probablemente no tenga habituación excesiva, esta condición podría surgir más adelante, especialmente si aumenta el desarrollo, y en particular el ecoturismo. La habituación excesiva es un problema que afecta a los monos carablanca en ciertos sitios secoturísticos de Costa Rica. Es de suma importancia que las consecuencias de la habituación excesiva se estudien más a fondo, principalmente en las áreas donde las actividades ecoturísticas atraen visitantes a los hábitats de la vida silvestre.

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