International Journal of Primatology最新文献

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.

The combination of meaning-bearing units (e.g., words) into higher-order structures (e.g., compound words and phrases) is integral to human language. Despite this central role of syntax in language, little is known about its evolutionary progression. Comparative data using animal communication systems offer potential insights, but only a handful of species have been identified to combine meaningful calls together into larger signals. We investigated a candidate for syntax-like structure in the highly social chestnut-crowned babbler (Pomatostomus ruficeps). Using a combination of behavioral observations, acoustic analyses, and playback experiments, we test whether the form and function of maternal contact calls is modified by combining the core "piping" elements of such calls with at least one other call element or call. Results from the acoustic analyses (236 analysed calls from 10 individuals) suggested that piping call elements can be flexibly initiated with either "peow" elements from middle-distance contact calls or adult "begging" calls to form "peow-pipe" and "beg-pipe" calls. Behavioral responses to playbacks (20 trials to 7 groups) of natural peow-pipe and beg-pipe calls were comparable to those of artificially generated versions of each call using peow elements and begging calls from other contexts. Furthermore, responses to playbacks (34 trials to 7 groups) of the three forms of maternal contact calls (piping alone, peow-pipe, beg-pipe) differed. Together these data suggest that meaning encoded in piping calls is modified by combining such calls with begging calls or peow elements used in other contexts and so provide rare empirical evidence for syntactic-like structuring in a nonhuman animal.

Social species live in groups that vary in size and composition for many reasons, including resource availability, predation risk, and space restrictions. Their social interactions reflect intraspecific interactions, social bonding, rank, reproductive status, and relatedness. Titi monkeys (Callicebus, Cheracebus, and Plecturocebus) are a diverse group of pitheciid primates that are widely distributed throughout South America. Typically, they live in small groups composed of a breeding pair and their offspring. Although social structure and interactions have been studied in captive titi monkeys, there has been much less research on free-ranging groups. We used all occurrence sampling during a 16-month period to investigate group composition and within-group social interactions in five wild groups of black-fronted titi monkeys, Callicebus nigrifrons living in an Atlantic Forest fragment at the Caraça Private Natural Heritage Reserve in Minas Gerais, Brazil. Unusually for the species, we found more than one adult male in three of our study groups (three adult males in one group and two in the other two groups). As reported for other titi monkeys, the breeding pair interacted more with each other than with any other group members. We also observed that breeding males interacted more with their offspring than breeding females did. Our results expand the existing literature on the social structure of titi monkeys, demonstrating their flexible social organization, providing further evidence of the breeding pair as the nucleus of the group and showing evidence for strong paternal care and stable attachments between breeding pairs in free-ranging C. nigrifrons.