American Journal of Primatology最新文献

Monitoring the abundance of widely distributed animals poses many logistic challenges, and is rarely done because the wide distribution generally suggests a lack of conservation concern and thus funding. However, as there are increasing concerns about the conservation status of some widely distributed primates, evidence based management requires estimates of abundance. In this paper we review how such estimates can be done and have been done for some animals. We also explore in depth the one attempt to do so for a primate, the long-tailed macaque. We identify weaknesses in the work that has been done and suggest how a reliable estimate could be obtained.

The ability to understand the internal (psychological or physiological) states of others can be adaptive in both cooperative and competitive settings. In this study, we tested whether tufted capuchin monkeys (Sapajus spp.) altered their willingness to share part of their food with a partner in relation to having recently seen it eating. We first gave partners food (banana, carrot, or nothing) that could not be shared with the subjects, and then gave subjects food (apple) that they could share with the partners. During the first phase of the tests, the subjects seemed aware that their partner was eating, but did not show any evident emotional response. Neither having seen the partner eat nor the quality of the food eaten by the partner had any effect on the subject's willingness to subsequently share their food during the second phase of the tests. Our results do not confirm those of a previous similar study, and suggest the effect of having seen the partner eat on subsequent food sharing is weak and/or variable in tufted capuchin monkeys. The ability of animals to understand the internal states of other individuals remains contentious.

Neopterin is a well-established biomarker of interferon-gamma-mediated macrophage activation that indicates cell-mediated immune system responses in humans. Because it is readily quantifiable in urine, it is increasingly used in nonhuman primates to study cell-mediated immune functioning in relation to infectious diseases, but also environmental and individual factors, in both captive and wild primates. This review synthesizes our current knowledge on these topics with a focus on nonhuman primates. We cover the influence of various methodological factors during sampling and analysis on the reliability of neopterin measurements and give practical advice on how these factors can be mitigated. Furthermore, we address the advantages and disadvantages of different biological matrices in which neopterin can be measured and propose best practice guidelines for handling and storage of samples that consider challenges encountered during fieldwork. We conclude this review with an outlook on topics within primatology where neopterin, as a marker of cell-mediated immune functioning, could become a valuable tool to answer applied questions and test evolutionary hypotheses about immune functioning in primates.

All 20 gibbon species (Hylobatidae) are listed as Threatened or Endangered on the IUCN Red List. The four species of gibbons occurring in Thailand survive only in well-protected forests and need to be effectively monitored for conservation management. Because of their habit of duetting and living in small-group territories, gibbons are usually surveyed using acoustic methods employing point counts. We surveyed the white-handed gibbon (Hylobates lar) population in Huai Kha Khaeng Wildlife Sanctuary in western Thailand to determine the long-term viability of the population. We combined the listening-point method using arrays of listening posts with the point transect Distance method with prior random placement of sample points. We placed 39 sample arrays in dry (seasonal) evergreen forest (DEF), the optimal forest type for gibbons in the sanctuary, and 34 arrays in selected areas of mixed deciduous forest (MDF). During the 20 months of survey (2017–2021), we estimated an average density of 3.74 groups km⁻² for DEF and 1.10 groups km⁻² for MDF. The total number of gibbon groups in the habitats was estimated at 2568 (95% CI: 2156–3063) in DEF and 1482 (95% CI: 1172–1887) in MDF. A multiple covariate distance sampling analysis revealed that forest type had a major effect on gibbon density, while altitude and distance to poaching signs had little or no effect. The most serious threat to gibbon populations in the WEFCOM complex in the future is likely to be increased dryness and degradation of forests caused by the global anthropomorphic increases in temperature.

Human activities are major threats to biodiversity, particularly for arboreal, forest-specialist species such as platyrrhine primates. Habitat loss and declines in vegetation quality negatively affect species' persistence in disturbed and human-modified landscapes. In this study, we evaluated the influence of landscape structure (forest cover and functional connectivity), vegetation quality and structure (EVI and canopy height), fire disturbance history (% burned area), and altitude on the occurrence of black-fronted titi monkeys (Callicebus nigrifrons) in the Cantareira-Mantiqueira Corridor, a region within the Atlantic Forest biodiversity hotspot. We conducted playback surveys at 72 sites to detect the presence of the species. Using model selection approaches, we assessed the relative importance of environmental predictors on the species' occurrence. The best-supported model included forest cover (within a 250 m radius) and altitude, indicating that greater forest cover at higher elevations best explains the presence of black-fronted titi monkeys. Variables related to functional connectivity, vegetation quality and structure and fire disturbance history had secondary importance. Our findings underscore the critical importance of preserving and restoring forested areas, particularly mid-elevation ranges (500–1200 m). These regions face the most severe degradation, posing a significant threat to black-fronted titi monkeys, a species currently listed as Near Threatened on the IUCN Red List. Our results align with previous studies showing positive associations between forest cover and the occurrence of congeneric species, reinforcing the urgent need for targeted conservation actions in increasingly degraded habitats.

Conservation education activities employing multimodal knowledge transmission, including art-based workshops, are a multidisciplinary tool that can be used to raise awareness of the natural environment in which we live. In this study, we implemented a conservation education workshop that combined different forms of knowledge transmission, to promote pro-environmental knowledge, attitudes, and behavioral intentions towards spider monkeys and their ecosystem, among 5- to 16-year-old students in a rural school in a Mayan community in Mexico (N = 27). The aim of the study was to (i) develop and implement a workshop tailored to the cultural context of Maya children in México, incorporating artistic activities and multimodal learning approaches, and (ii) evaluate its effectiveness by monitoring changes in participants' knowledge, attitudes, and behavioral intentions towards spider monkeys and their ecosystem. Our findings indicate overall increases in conservation-oriented knowledge and behavioral intentions following the workshop, with more pronounced gains in knowledge among girls and in behavioral intentions among older children. Attitudes toward spider monkeys were already high before the intervention and showed a small but statistically significant increase afterward. Children's drawings reflected increased references to morphological and ecological traits, although aspects related to social behavior and human-monkey interactions were less represented. These outcomes suggest that short-term, culturally embedded and multimodal educational interventions may promote conservation learning in rural communities, though some effects may be constrained by ceiling effects and topic complexity. Future research should explore the durability of these changes over time, the specific drivers of pre-existing pro-environmental attitudes, and the impact of prior familiarity and cultural context on learning outcomes.