American Journal of Primatology最新文献

{"title":"Chimpanzee Activity and Behavioral Diversity Extends Across 24 Hours in Both Captive and Wild Settings","authors":"Jake A. Funkhouser,&nbsp;Helen Boostrom,&nbsp;Heidi Hellmuth,&nbsp;Logan Lacy,&nbsp;Sophie Bekins,&nbsp;Priyanka Joshi,&nbsp;Wen Mayoukou,&nbsp;Severin Ndassoba,&nbsp;Chigue Singono,&nbsp;Claude Abedine,&nbsp;Crepin Eyana Ayina,&nbsp;Emma Claisse,&nbsp;Emmalee Eslinger,&nbsp;Philip McElmurray,&nbsp;Stephanie Musgrave,&nbsp;David Morgan,&nbsp;Crickette Sanz","doi":"10.1002/ajp.23729","DOIUrl":"10.1002/ajp.23729","url":null,"abstract":"<div>\u0000 \u0000 <p>Studying nocturnal behavior is crucial for understanding the full scope of a species' behavioral flexibility so as to inform the conservation of wild populations and the care of captive individuals. However, this aspect of primate behavior is understudied, especially in great apes, which exhibit some of the widest documented behavioral diversity and flexibility. Our investigation is among the first to systematically compare the 24 h activity patterns and behavioral activities of captive chimpanzees (Saint Louis Zoo, USA) with those of wild chimpanzees (three sites across the Nouabalé-Ndoki National Park in the Republic of Congo) and a published data set of the nocturnal behavior of all chimpanzee subspecies. Furthermore, we examined the influence of human activity and changes to the group's composition on the activity patterns and nocturnal behaviors of the zoo-living chimpanzees. Our results reveal that the zoo-living chimpanzees exhibit significantly different activity patterns compared to their wild counterparts, with increased nocturnal activity (particularly in the early morning) and more observations of feeding and social behaviors at night. Additionally, the absence of human visitors and a change in the group's composition were found to influence these activity patterns. These findings underscore the importance of integrating more holistic approaches to captive primate care and wild primate conservation. This study also highlights the immense potential of implementing remote monitoring technology, such as video camera traps, across contexts. Such data that extend across contexts benefit not only the captive and wild great apes but also provide opportunities for caregivers, conservation managers, and students who are involved in these collaborative initiatives.</p></div>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142998483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monkeys Swimming Across Rivers Refine Questions About the Riverine Barrier Hypothesis","authors":"Mary S. M. Pavelka,&nbsp;Shannon Holland,&nbsp;Broden Sabados,&nbsp;Amanda D. Melin","doi":"10.1002/ajp.23707","DOIUrl":"10.1002/ajp.23707","url":null,"abstract":"<p>The Riverine Barrier Hypothesis posits that species distributions are limited by large rivers acting as geographical barriers. Accordingly, large rivers have long been thought to be a major driver of the extensive speciation and high levels of biodiversity among platyrrhine primates in South and Central America. Direct observations of river crossings provide evidence that complements studies of genetic diversity that can together shed new light on this hypothesis. Here, we discuss recent video evidence of howler monkeys successfully swimming across the Rupununi River in Guyana and the Panama Canal. The footage clearly reveals that howler monkeys can and do cross such bodies of water. These video observations help to refine questions about the species and circumstances under which rivers are barriers to gene flow. We end by joining other scientists who call for increased collaborations with local people living near river crossing sites to improve our knowledge and understanding of the frequency, contexts, and traits of the rivers and animals that characterize river crossings. Local knowledge provides new answers and helps refine questions about the river barrier hypothesis.</p>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11734091/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142982425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tackling Hominin Tickling: Bonobos Share the Social Features and Developmental Dynamics of Play Tickling With Humans","authors":"Elisa Demuru,&nbsp;Ilenia Montello,&nbsp;Jean-Pascal Guéry,&nbsp;François Pellegrino,&nbsp;Florence Levréro,&nbsp;Ivan Norscia","doi":"10.1002/ajp.23723","DOIUrl":"10.1002/ajp.23723","url":null,"abstract":"<p>It is under debate whether intersubjectivity—the capacity to experience a sense of <i>togetherness</i> around an action—is unique to humans. In humans, heavy tickling—a repeated body probing play that causes an automatic response including uncontrollable laughter (gargalesis)—has been linked to the emergence of intersubjectivity as it is aimed at making others laugh (self-generated responses are inhibited), it is often asymmetrical (older to younger subjects), and it elicits agent-dependent responses (pleasant/unpleasant depending on social bond). Intraspecific tickling and the related gargalesis response have been reported in humans, chimpanzees, and anecdotally in other great apes, potentially setting the line between hominids and other anthropoids. Here we investigated this phenomenon in bonobos and predicted that in this species (sharing with humans and chimpanzees the last common ancestor) the presence of tickling would be modulated depending on the players' age, play session initiators, and familiarity. In April–June 2018, we collected videos on play sessions—including tickling—on a bonobo group housed at <i>La Vallée des Singes</i> (France). We showed that tickling received decreased while tickling performed increased with age, with tickling being mostly directed from older to younger individuals. Moreover, tickling was mostly performed by the individuals that started the play interaction and most of it occurred in strongly bonded dyads, particularly mother–infant ones. Bonobo tickling features, especially age profile and social modulation, mirror those of heavy tickling in humans thus suggesting a common evolutionary origin and shared patterns of basic intersubjectivity in hominins.</p>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11734381/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142982430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Botfly Parasitism on the Behavior of Mantled Howler Monkeys","authors":"Ricardo J. Ortíz-Zárate,&nbsp;Jurgi Cristóbal-Azkarate,&nbsp;Ariadna Rangel-Negrín,&nbsp;Alejandro Coyohua-Fuentes,&nbsp;Pedro A. D. Dias","doi":"10.1002/ajp.23731","DOIUrl":"10.1002/ajp.23731","url":null,"abstract":"<div>\u0000 \u0000 <p>Parasitism, a widespread nutrient acquisition strategy among animals, results from a long evolutionary history where one species derives its metabolic needs from another. Parasites can significantly reduce host fitness, affecting reproduction, growth, and survivability. Vertebrate hosts exhibit defensive strategies against parasites, including “sickness behaviors” such as lethargy and self-grooming to remove ectoparasites. In addition, social animals may engage in “helping sick animals” behaviors, such as social grooming, to aid parasitized group members. Mantled howler monkeys (<i>Alouatta palliata</i>) parasitized by botfly larvae (<i>Cuterebra baeri</i>) exhibit subdermal nodules, which can be fatal under nutritional stress. This study investigates whether mantled howler monkeys display sickness behaviors or helping behaviors in response to <i>C. baeri</i> parasitism. Observations from July 2022 to April 2023 in La Flor de Catemaco, Mexico, revealed that parasitized individuals did not increase the frequency of self-directed (rub, scratch, and touch) nor received helping behaviors (social scratch and social touch) compared to non-parasitized ones. However, parasitized monkeys were more active, spending more time feeding and moving, likely to compensate for the metabolic costs of parasitism. This shift from energy conservation to energy acquisition strategies suggests a complex response to parasitism, emphasizing the need for further research on the energetic impacts of parasitism in this species. These preliminary findings suggest behavioral flexibility by mantled howler monkeys in coping with infection, indicating potential adaptive strategies to mitigate the adverse effects of parasitism.</p></div>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142998488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Roadside Dining: The Collective Movement Behavior of Sulawesi Moor Macaques in a Provisioning Context","authors":"Joshua Trinidad,&nbsp;Henry R. Scharf,&nbsp;Putu Oka Ngakan,&nbsp;Erin P. Riley","doi":"10.1002/ajp.23727","DOIUrl":"10.1002/ajp.23727","url":null,"abstract":"<p>How group-living primates come to a consensus about navigating their environment is a result of their decision-making processes. Although decision-making has been examined in several primate taxa, it remains underexplored for primates living in anthropogenic landscapes. To shed light on consensus decision-making and flexibility in this process, we examined collective movement behavior in a group of wild moor macaques (<i>Macaca maura</i>) experiencing a risk-reward tradeoff as a result of roadside provisioning within Bantimurung Bulusaraung National Park in South Sulawesi, Indonesia. Our goal was to determine whether individual characteristics (e.g., sex, dominance rank, and/or social network centrality) predict the likelihood of initiating a collective movement and if the opportunity to receive food provisions along the road alters these patterns. Using the all-occurrences method, we recorded the location, time, and identity of initiators and followers of each collective movement observed from April to June 2023 (<i>N</i> = 61). We used conditional logistic regression models to examine which individual characteristics predicted initiation overall and based on two destination categories: forest- and road-directed collective movements. Initiation was distributed amongst most of the group, indicating a partially-shared decision-making style. Overall, adult males were more likely to initiate collective movements than adult females. However, for collective movements directed toward the risky roadside, dominance, rather than sex, was a better predictor of initiation, with higher ranked individuals being more likely to initiate collective movements. Examining the decision-making processes in this species through collective movements can provide insight into how primates come to a consensus and the extent to which anthropogenic factors shape these processes. By shedding light on how moor macaques navigate the risk-reward tradeoff at this site, our results can also inform the management of human-macaque interfaces.</p>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11725772/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142969457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How Do Common Marmosets Maintain the Balance Between Response Execution and Action Inhibition?","authors":"Ranshikha Samandra,&nbsp;Marcello G. P. Rosa,&nbsp;Farshad A. Mansouri","doi":"10.1002/ajp.23717","DOIUrl":"10.1002/ajp.23717","url":null,"abstract":"<p>Socio-dynamic situations require a balance between response execution and action inhibition. Nonadaptive imbalance between response inhibition and execution exists in neurodevelopmental and neuropsychological disorders. To investigate the underlying neural mechanisms of cognitive control and the related deficits, comparative studies in human and nonhuman primates are crucial. Previous stop-signal tasks in humans and macaque monkeys have examined response execution (response time (RT) and accuracy in Go trials) and action inhibition (stop-signal reaction time (SSRT)). Even though marmosets are generally considered suitable translational animal models for research on social and cognitive deficits, their ability to inhibit behavior remains poorly characterized. We developed a marmoset stop-signal task, in which RT could be measured at millisecond resolution. All four marmosets performed many repeated Go trials with high accuracy (≥ 70%). Additionally, all marmosets successfully performed Stop trials. Using a performance-dependent tracking procedure, the accuracy in Stop trials was maintained around 50%, which enabled reliable SSRT estimates in marmosets for the first time. The mean SSRT values across sessions ranged between 677 and 1464 ms across the four marmosets. We also validated the suitability and practicality of this novel task for examining executive functions by testing the effects of a natural hormone, oxytocin, on response execution and action inhibition in marmosets. This marmoset model, for reliable (millisecond resolution) assessment of the balance between response execution and inhibition, will further facilitate studying the developmental alterations in inhibition ability and examining the effects of various contextual and environmental factors on marmosets' executive functions.</p>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11714342/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142942743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hand Preferences in Olive Baboons (Papio anubis) During Cognitive Performance on Match-to-Sample Tasks and Natural Behaviors","authors":"Logan R. Brownell,&nbsp;Jessica F. Cantlon,&nbsp;Caroline M. DeLong","doi":"10.1002/ajp.23728","DOIUrl":"10.1002/ajp.23728","url":null,"abstract":"<div>\u0000 \u0000 <p>An individual shows handedness when they consistently prefer one hand over the other for tasks that can be performed with either hand. Humans have a population-level right-hand preference, and past research shows that a variety of nonhuman primate species also show hand preferences. More complex manual tasks elicit stronger hand preferences than less complex manual tasks, but not much is known about hand preferences during a cognitive task in nonhuman primates. The current study investigated hand preferences in olive baboons (<i>Papio anubis</i>). Seven baboons participated in a match-to-sample task on a touchscreen computer. We recorded each baboon's hand use as they touched the start box, sample stimulus, choice stimulus, and which hand they used to retrieve the food reward. All 10 baboons in the troop were also observed in their outdoor zoo habitat, where they were carrying out natural behaviors. In the current study, the touchscreen task was cognitively demanding, without being manually complex, as the baboon simply touched the screen. The direction and strength of hand preference were calculated using <i>z</i>-scores and handedness index (HI) scores for each individual baboon. When completing the cognitive task, five baboons were left-handed, and two baboons were right-handed. Five of the baboons had strong preferences (three left-handed and two right-handed) and two had weak preferences. When engaging in natural behaviors, eight baboons were left-handed, one baboon was right-handed, and one baboon was ambiguously handed. Two of the baboons had strong preferences (one right-handed and one left-handed), and eight had weak preferences. Four of the seven baboons had consistent hand preferences when completing the cognitive task and when engaging in natural behaviors in their habitat. These results show that similar to manually complex tasks, a complex cognitive task such as match-to-sample elicits stronger and more directional hand preferences than natural behaviors.</p></div>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142942739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to “Stable Isotopes Analysis of Black Lion Tamarins Reveals Increasing Arthropod Consumption When Fruit Productivity Decreases in Forest Fragments”","authors":"","doi":"10.1002/ajp.23730","DOIUrl":"10.1002/ajp.23730","url":null,"abstract":"<p>Raskin, A., O. Kaisin, L. N. Michel, et al. 2025. “Stable Isotopes Analysis of Black Lion Tamarins Reveals Increasing Arthropod Consumption When Fruit Productivity Decreases in Forest Fragments.” <i>American Journal of Primatology</i> 87: e23698. https://doi.org/10.1002/ajp.23698.</p><p>In the originally published version of this article, Felipe Bufalo was missing from the author list. The complete author list is as follows:</p><p>Amazone Raskin, Olivier Kaisin, Loïc N. Michel, Benjamin Lejeune, Gilles Lepoint, Rodrigo Gonçalves Amaral, Felipe Bufalo, Gabriel Pavan Sabino, Márcio Silva Araújo, Gabriela Cabral Rezende, Fany Brotcorne, Laurence Culot</p><p>Felipe Bufalo's affiliation is as follows:</p><p>Laboratório de Primatologia, Departamento de Biodiversidade, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro, São Paulo, Brazil.</p><p>Felipe Bufalo's contributions are data curation (supporting), methodology (supporting).</p><p>In the acknowledgements, the following sentence should have been added: FB received a fellowship from FAPESP (#2023/01760-0), from CAPES (#88881.846203/2023-01), and from the Brazilian National Council for Scientific and Technological Development (CNPq: #133172/2018-0 and #443489/2020-3).</p><p>The online version of the article has been updated accordingly.</p><p>We apologize for this error.</p>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajp.23730","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142942737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"History of Health at Cayo Santiago—An Investigation of Environmental and Genetic Influences on the Skeletal Remains of the Introduced Rhesus Macaque (Macaca mulatta) Colony","authors":"George Francis,&nbsp;Qian Wang","doi":"10.1002/ajp.23722","DOIUrl":"10.1002/ajp.23722","url":null,"abstract":"<div>\u0000 \u0000 <p>The Cayo Santiago rhesus macaque colony is a renowned primate population that has experienced significant natural and anthropogenic ecological variation in their 85-year history. Demographic and familial information is also tracked and collated for the majority of monkeys. Thus, the health history of rhesus macaques at Cayo Santiago should reflect the impacts of both environmental and genetic factors. In this study, we utilized a sample of skeletal remains comprised of 2787 individuals (1571 females, 1091 males), born between 1938 and 2017 from the derived skeletal collection of the primate colony to assess variation in survivorship, pathology, bone mineral density (BMD), and dental eruption status, in the context of hurricane impacts, nutritional fluctuations, and matriline genealogy. Results demonstrated that rhesus macaques at Cayo Santiago exhibit a range of skeletal pathologies that encompass biomedical and archaeological significance, multiple etiologies, severities, locations, and types, in addition to a secular trend of declining BMD that is hypothesized to reflect decreasing physical activity levels under increasing population densities. Specifically, hurricane impacts were found to increase the rate of systemic disease, decrease BMD in young adults, and delay eruption of the primary dentition. Certain matrilines exhibited heightened levels of systemic disease at early ages while others exhibited greater rates of congenital disease. Early-life adversity, through the experience of major hurricanes, may enhance inflammatory pathways, heightening the risk of disease and accelerating the aging process leading to reduced BMD. Such impacts may underly greater levels of observed infection post-hurricane through intensification of pathogen transmission and disease rates brought on by hurricane-adaptive social strategies that favor closer proximity. Familial susceptibility to disease indicates heritable host genetic factors are likely influencing disease patterning in the population. A cluster of congenital diseases may most convincingly illustrate this, or alternatively reflects low levels of genetic diversity in the population.</p></div>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142942741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stone Tool Use by Black-Horned Capuchin Monkeys (Sapajus nigritus cucullatus) in an Urban Park in Londrina, Brazil","authors":"Julia Santos Gutierres,&nbsp;Felipe Santos Machado Pereira,&nbsp;Jessica Ward Lynch,&nbsp;Ana Paula Vidotto Magnoni","doi":"10.1002/ajp.23704","DOIUrl":"10.1002/ajp.23704","url":null,"abstract":"<div>\u0000 \u0000 <p>Tool use to crack open palm nuts has been observed extensively in some capuchin monkey species. However, for southern black-horned capuchin monkeys (<i>Sapajus nigritus cucullatus</i>), there is only one published record of stone tool use from the 1990s, from an urban park in Londrina, Brazil. In the present study, we returned to this urban park to systematically investigate the hammer-and-anvil sites used to crack nuts by this capuchin monkey population. We analyzed the fruit and shell remnants resulting from hammering to test the following hypotheses: (1) hammers at tool-use sites are actively chosen for size and/or weight, (2) tool use sites that are closer to a tree of the processed plant species are more frequently used, and (3) there is no seasonal effect modulating hammer-and-anvil use for processing nuts. We located and identified 205 tool-use sites through active search within the park, and we measured and weighed the tools involved in hammering activity. We compared hammer weight and size to that of the comparable material available in the environment and found that hammer size and weight differed significantly from that of the raw materials found in the environment, suggesting active choice of the hammers. We identified three plant species for which nuts were processed through tool use: <i>Syagrus romanzoffiana</i>, <i>Acrocomia aculeata</i> and <i>Terminalia catappa</i>. Through measuring the distance between each tool-use site and the nearest tree of the plant species processed there, we found that closer proximity between the tool-use site and the nearest target tree (<i>Syagrus</i> and <i>Acrocomia</i>) increased cracking frequency. We returned to each site three times during the study year to determine if new tool use activity had occurred, and our data indicate habitual use of tools to crack open nuts throughout the year, with no large differences between seasons.</p></div>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"87 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142920535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}