International Journal of Primatology最新文献

Ranging behavior, including home range use and daily travel distance, provides valuable information on the behavioral responses of primates to their habitats. We evaluated the ranging behavior of wild silvery lutungs (Trachypithecus cristatus) inhabiting a coastal forest in West Sumatra, Indonesia, for 614 h over 15 months in 2018–2021, focusing on the relationships between ranging behavior and activity budgets, dietary composition, and food availability. The annual home range was 8.1 ha (minimum convex polygon) and 11.7 ha (95% kernel), and the mean (± standard deviation [SD]) daily travel distance was 926 ± 385 m. Daily travel distance showed a positive correlation with percent resting and negative correlations with percent feeding and moving. Furthermore, daily travel distance was correlated positively with percent young leaf feeding and negatively with percent mature leaf feeding, ripe fruit feeding, and dietary diversity. In contrast, home range size did not vary significantly across the study period, and we found few significant correlations between home range size and dietary composition or activity budget. The longer daily travel distances in food scarce season are likely due to the lutungs needing to travel further to find trees bearing young leaves. We conclude that the silvery lutungs’ ranging behavior is linked to their high-risk, high-return strategy.

The conservation of endangered primates often relies on data on population dynamics and health obtained from individuals captured with baited traps. This could increase the risk of injury or predation by attracting competitors and predators to the baited locations. It also can lead to unforeseen interactions of ecological significance among nontarget species. We evaluated these hypotheses by monitoring visits by multiple species to capture platforms for endangered golden lion tamarins (Leontopithecus rosalia). We placed camera traps on ten platforms baited with bananas resulting in more than 1500 species records. We calculated species richness and temporal patterns of visitation overlap among lion tamarins, predators, and competitor species. We also fitted a lion tamarin group with a GPS telemetry transmitter to assess whether movements toward and visits to the platform occurred more than expected by chance. Thirteen mammals and 12 bird species visited the platforms. There was high temporal overlap, albeit with peaks at different times, with the tayra (Eira barbara)—a main predator. Introduced hybrid marmosets (Callithrix spp.) were present on the platforms in 42% of visits by lion tamarins, and we recorded fights between the two species. There was significant temporal overlap between lion tamarins and capuchin monkeys. The lion tamarin visitation rate to platforms did not differ from random locations, nor did they show significant recursive behavior. Lion tamarins were vigilant in 90% of platform visits and emitted mild alarm calls, mobbing calls, and food calls. Their vocal output increased when marmosets were on the platforms. We suggest that lion tamarins consider the platforms an attractive, albeit risky, food resource. Baited platforms attract species beyond the target species and create conditions for unintended potentially negative effects on multiple species.

Conservation is a major topic in primatology. In addition to focusing on individual species, the protection of interaction networks is key to conservation success, but difficulties in identifying these networks hinder research. We hope to inspire research in primate conservation through network analysis. We illustrate an approach for studying species networks using data for Tibetan macaques (Macaca thibetana) in three national nature reserves in Sichuan Province, China: Wolong, Tangjiahe, and Heizhugou. With data on species presence/absence from 185 cameras each continuously working for >12 months, we used the Phi coefficient r_ø to identify spatial association networks between species and the Lambda statistic L_B to test the properties of the associations. We identified four networks across the reserves. Tibetan macaques were associated with four terrestrial/semi-arboreal bird and mammal species in Wolong and nine species in Tangjiahe, but only two species in Heizhugou. Macaques formed symmetrical associations, suggesting competition, unidirectional asymmetrical associations, suggesting commensalism, and bidirectional asymmetrical associations, suggesting mutualism. The macaque’s community environment may be predation-free. Commensal and mutualistic interactions with Sichuan snub-nosed monkeys (Rhinopithecus roxellana) and three other species may enhance the ecological fitness of Tibetan macaques in Tangjiahe over that in Wolong and conservation investment for the macaque in Tangjiahe may benefit more species than that in Wolong. Asymmetrical associations may facilitate the ecological restoration of the degraded community in Heizhugou. Our approach may provide a sensitive method for ecological monitoring for conservation management, and facilitate primate community ecological research.

The illegal primate trade is one of the major drivers of the decline of nonhuman primate populations and a threat to their wellbeing. Thousands of trafficked primates enter rescue centers every year, and their destiny (release back into the wild, long-term captivity, or euthanasia) involves controversial decisions and complex ethical considerations. To navigate these issues, we developed an ethical matrix, an ethical framework previously used to address conservation-related issues. We gathered information from studies on the reintroduction of trafficked platyrrhines in Latin America from 1990 to 2022 to develop the matrix. We found 22 studies performed in eight Latin American countries, which included howler monkeys, spider monkeys, woolly monkeys, capuchin monkeys, squirrel monkeys, marmosets, and tamarins. We found that the reintroduction of trafficked platyrrhines may yield positive results for the welfare of individuals and for the conservation of their taxa and some of the potential negative effects, such as spillover of infectious agents to free-ranging populations or to human populations, or competition for resources between reintroduced monkeys and resident conspecifics have not yet been documented in the scientific literature, although this does not mean that they do not occur. We conclude that the ethical matrix is a useful method to consider the interests of all potential stakeholders and that the reintroduction of trafficked primates may be a viable management option if the individual welfare of the animals is considered, programs comply with the IUCN and government guidelines, and the objective and justification of the reintroduction are clear.

Abstract

Characterizing genetically distinct populations of primates is important for protecting biodiversity and effectively allocating conservation resources. Skywalker gibbons (Hoolock tianxing) were first described in 2017, with the only confirmed population consisting of 150 individuals in Mt. Gaoligong, Yunnan Province, China. Based on river geography, the distribution of the skywalker gibbon has been hypothesized to extend into Myanmar between the N’Mai Kha and Ayeyarwaddy Rivers to the west, and the Salween River (named the Thanlwin River in Myanmar and Nujiang River in China) to the east. We conducted acoustic point-count sampling surveys, collected noninvasive samples for molecular mitochondrial cytochrome b gene identification, and took photographs for morphological identification at six sites in Kachin State and three sites in Shan State to determine the presence of skywalker gibbons in predicted suitable forest areas in Myanmar. We also conducted 50 semistructured interviews with members of communities surrounding gibbon range forests to understand potential threats. In Kachin State, we audio-recorded 23 gibbon groups with group densities ranging between 0.57 and 3.6 group/km². In Shan State, we audio-recorded 21 gibbon groups with group densities ranging between 0.134 and 1.0 group/km². Based on genetic data obtained from skin and saliva samples, the gibbons were identified as skywalker gibbons (99.54–100% identity). Although these findings increase the species’ known population size and confirmed distribution, skywalker gibbons in Myanmar are threatened by local habitat loss, degradation, and fragmentation. Most of the skywalker gibbon population in Myanmar exists outside protected areas. Therefore, the IUCN Red List status of the skywalker gibbon should remain as Endangered.

Combinatorial behavior involves combining different elements into larger aggregates with meaning. It is generally contrasted with compositionality, which involves the combining of meaningful elements into larger constituents whose meaning is derived from its component parts. Combinatoriality is commonly considered a capacity found in primates and other animals, whereas compositionality often is considered uniquely human. Questioning the validity of this claim, this multidisciplinary special issue of the International Journal of Primatology unites papers that each study aspects of combinatoriality and compositionality found in primate and bird communication systems, tool use, skills, and human language. The majority of authors conclude that compositionality is evolutionarily preceded by combinatoriality and that neither are uniquely human. This introduction briefly introduces readers to the major findings and issues raised by the contributors.

Human language, hominin tool production modes, and multimodal communications systems of primates and other animals are currently well-studied for how they display compositionality or combinatoriality. In all cases, the former is defined as a kind of hierarchical nesting and the latter as a lack thereof. In this article, I extend research on combinatoriality and compositionality further to investigations of everyday primate skills. Daily locomotion modes as well as behaviors associated with subsistence practices, hygiene, or body modification rely on the hierarchical nesting of different behavioral and cognitive actions into complex skills. I introduce a scheme which uses hierarchical organization to differentiate combinatorial from compositional skills. Combinatorial skills are defined either as aggregational or linearly hierarchical depending on whether the skill occurs momentarily in space or unfolds sequentially over time. Compositional skills are defined either as nested or interactionally hierarchical depending on whether the skill results in new constructs or in new interactions between existing constructs. The methodology I propose combines epistemological hierarchy theory with data from primatological field research and experimental and comparative psychological research and provides a means to integrate current constructionist and extended views on cognition and action with older research on behavioral logics in psychology and operational chain thinking in anthropology. The approach furthermore synchronizes with ongoing research on teleonomy, intentionality, and creativity.

Abstract

Play is thought to serve different purposes at different times during ontogeny. The nature and frequency of play are expected to change accordingly over the developmental trajectory and with socio-ecological context. Orangutans offer the opportunity to disentangle the ontogenetic trajectories of solitary and social play with their extended immature phase, and socio-ecological variation among populations and species. We evaluated the frequency of play in 39 immature individuals across two populations (Pongo pygmaeus wurmbii, at Tuanan, Borneo, and P. abelii at Suaq, Sumatra), age (0–11 years), sex, and social context, using more than 11 500 h of full-day focal observation data. We found independent age trajectories of different play types, with solitary object and solitary locomotor peaking before social play. Social play partners changed during ontogeny, and male immatures were more likely to engage in non-mother social play than females. Overall, social play was more frequent at Suaq than Tuanan, linked to the more frequent availability of partners. Furthermore, per time in association with conspecifics, Tuanan immatures were as likely to engage in social play as their peers at Suaq, suggesting similar intrinsic motivation. Increasing fruit availability correlated with both longer associations and increased social play frequency in the less sociable population of Tuanan, but not at Suaq. Our findings on orangutans support evidence from other species that different play types follow different developmental trajectories, vary with sex, social opportunities, and ecological context. Although drawing functional inferences is challenging, the distinct developmental trajectories reflecting adult sociability and behavioral repertoires may indicate that play serves several, non-mutually exclusive functions during ontogeny.

Many primate species are threatened by the pet trade, and rehabilitated monkeys require suitable habitats for release back into the wild. The process of identifying suitable release sites involves finding areas with adequate resources and minimizing negative impacts on resident species and human populations. To address this challenge, this study was designed to identify and map suitable areas for the reintroduction of bearded capuchin monkeys (Sapajus libidinosus) into the Caatinga biome in northeastern Brazil. We used a multicriteria decision analysis (MCDA) to identify suitable release areas. Using a species distribution model, we located suitable habitats for seven species of vegetation that are vital resources during the dry season: Syagrus romanzoffiana, Attalea speciosa, Syagrus oleracea, Commiphora leptophloeos, Manihot epruinosa, Pilosocereus pachycladus, and Tacinga inamoena. We then created an MCDA by using vegetation suitability, water availability, proximity to protected areas, and distance from roads and cities as key variables. To increase accessibility, we coded the results into a Google Earth Engine app, allowing for easy and free access to researchers and others interested in capuchin monkey conservation. The resulting suitability maps cover the entire Caatinga biome, providing a valuable tool for conservation efforts by simplifying the initial step of locating potential release sites. This study demonstrates the application of geospatial tools in mapping suitable habitats for the translocation and release of rehabilitated primates at a time when biodiversity loss, the exotic pet trade, land use change, and climate change are threatening nonhuman primates worldwide.