Primates最新文献

This is the story of how I became a primatologist, and the major research projects and activities in my career specializing in the ecology, behavior, and conservation of gibbons. After graduate training in zoology, I spent two years as an officer in the U. S. Army's Medical Service Corps and was assigned to the SEATO Medical Research Laboratory in Bangkok. My assignments included caring for a colony of captive gibbons (Hylobates lar) released on an island to produce animals for experimental research on diseases. After my army career, I relocated to Thailand in 1973 and my interests turned to wild gibbons in the forests of Thailand. My career in Thailand was spent teaching ecology in the biology department of Mahidol University. After retirement, I continued working at BIOTEC, National Science and Technology Development Agency, and established a large forest dynamics research plot in the Mo Singto gibbon study site in Khao Yai National Park. Research carried out in Khao Yai included study of the ecology and social behavior of gibbons, plant seed dispersal, and relations between Hylobates lar and H. pileatus, whose distributions overlap in a small area of the park. I describe some of the conservation activities I have been involved in, which include development of sampling techniques for gibbon populations, survey of wild gibbons, reintroduction of gibbons, and publication of books on primates for children. Finally, I offer some recommendations on how to become a primatologist.

Habitat disturbances, including stochastic events such as disease outbreaks, can significantly affect primate populations by reducing population density and demographic structure. The black-and-gold howler monkey (Alouatta caraya, IUCN: Near Threatened) is the southernmost species of the genus Alouatta and inhabits a variety of environments throughout its distributional range. In Argentina, A. caraya is classified as vulnerable, but following a yellow fever outbreak (YFO) between 2007 and 2009, the subpopulations in the province of Misiones were reclassified as Endangered. This study provides, for the first time, density estimates for two sites in southern Misiones where monkey mortality was reported during the 2007-2009 YFO, as well as for four sites in northern Corrientes, where no YFO-related mortality has been documented. All sites are located within the Southern Cone Mesopotamian Savanna (SCMS) ecoregion. We identified 34 groups of A. caraya-17 in Misiones and 17 in Corrientes. In Misiones, we recorded one of the lowest A. caraya densities reported in Argentina, with only 0.33 individuals per hectare (mean = 0.31, SD ± 0.12). In contrast, densities in Corrientes reached up to 1.34 individuals per hectare (mean = 1.11, SD ± 0.18), consistent with previously reported values for the species. These preliminary results suggest that density variation within the same ecoregion may be linked to population declines in areas affected by yellow fever (YF). Nonetheless, the presence of three groups with only three individuals each in Misiones may indicate early signs of recolonization or population expansion in the aftermath of the outbreak.

Altitudinal variation plays a key role in structuring ecological communities, as increasing elevation leads to lower temperatures and reduced ecosystem productivity. These environmental constraints can be particularly limiting for species with low thermal tolerance, restricting resource availability and influencing species persistence, distribution, and population densities. Several models describe the relationship between species richness and altitude, with the monotonic decreasing and the Intermediate Domain Model being the most reported. However, the extent to which these patterns apply to different primate species and regions remains poorly understood. Here, we evaluated how primate abundance and species richness vary at different altitudinal levels in the Eastern Andes of Colombia and analyzed the relationship between fruit productivity and primate biomass. We used line transects to estimate the density of diurnal primates at three altitudinal levels (low: 800-1300 m, medium: 1300-1800 m, and high: 1800-2300 m), from which we calculated primate biomass. We measured fruit productivity for 1 year using 50 hanging mesh traps per altitudinal level along transects. We found that primate biomass and fruit productivity were higher at low and medium elevations compared to high elevations, although no significant differences were observed between the first two. Our results do not fully align with commonly reported patterns in the literature based on gradual changes with altitude. In our study system, habitat productivity was associated with primate distribution and biomass. Our results highlight the importance of long-term studies across multiple mountainous sites to better understand the mechanisms shaping primate communities.

Predation risk fundamentally shapes primate social structure by influencing cooperation, competition, and spatial organization within groups. Although domestic dogs (Canis lupus familiaris) represent one of the world's most impactful invasive species affecting wildlife, their influence on primate social structure remains largely understudied. We examined how dog presence and barks influence interindividual proximity among group members in mantled howler monkeys (Alouatta palliata). We studied two habituated groups (10 and 8 adults, respectively) in Veracruz, Mexico, combining 242 h of observational data with experimental playbacks of dog barks at different intensities (40 and 80 dB). We calculated proximity indices from instantaneous sampling of interindividual proximity. Howler monkeys were closer immediately following exposure to dogs, partially supporting our hypothesis that interindividual proximity would change in response to dogs. Contrary to predictions, individuals were farther from each other as bark intensity increased and as proximity to dog stimuli decreased. During longer timeframes, individuals were closer when exposed to low-intensity barks compared to periods without dog stimuli. These findings demonstrate that dogs influence howler monkey spatial organization through context-dependent effects that vary with stimulus characteristics and temporal scale. Despite the short-term nature of this study, the consistency between observational and experimental results suggests these patterns are reliable. Therefore, these results contribute to our understanding of how invasive predators affect primate social structure and highlight the importance of managing free-ranging dogs in areas where they overlap with wildlife populations.

We report behavioral responses to four dying and dead adult companions (two aged alpha males, one high-ranking adult male, and one aged, high-ranking female) in a free-ranging, provisioned group of Japanese macaques, with particular interest in whether external, visible bodily damage to the deceased individuals and social affinity with them influenced responses of group members. All but one moved away or stayed away from the dying or dead individuals when they noticed maggots on them, likely indicating an aversion to maggots (Cases 1, 2, and 3). However, some individuals remained near the corpse of an adult male that had no noticeable external damage, and a juvenile female whose mother was his most frequent proximity partner groomed him (Case 4). One adult female who ate maggots while grooming the dying alpha male (Case 1) and most individuals who remained relatively close to another alpha male's rain-drenched dead body (Case 2) were also affiliated with those two alpha males prior to their deaths. We conclude that Japanese monkeys have a strong tendency to avoid dying and dead adult companions already infested with maggots but that some individuals with social affinity with the deceased may contact or at least remain near the latter for some time. We discuss monkeys' possible perceptions when encountering corpses, in relation to non-human primates' awareness of death.

Understanding the meanings of names given to endangered animals is important because these names might influence how local communities perceive the animals. Influenced by name connotations, these perceptions may shape how communities support or oppose our conservation efforts. Conducted across nine villages within the Batang Toru ecosystem, this research involved 90 respondents. The study incorporated in-depth interviews and content analysis using a qualitative approach. Our findings reveal five local names for the Tapanuli orangutan: 'orang utan,' 'nihagatua,' 'mawas,' 'maos,' and 'juhut bontar.' The term 'juhut bontar,' which translates to bloody meat, is significantly linked to the perception of orangutans as bushmeat, reflecting an attitude not consistent with species conservation. Consequently, we recommend discontinuing this term in local conservation campaigns. Our sample size was insufficient to conclusively determine whether non-indigenous names with potentially positive connotations due to the meaning 'person of the forest' (i.e., 'orang utan' and 'nihagatua') or rather indigenous names with neutral meaning (i.e., 'mawas' and 'maos') support pro-conservation attitudes.

Through primatology, I realized it was possible to examine sociality from a perspective outside of the human species. I joined Kyoto University's Laboratory of Physical Anthropology under the supervision of Imanishi Kinji and Itani Junichiro. I decided to pursue field-based discovery research on Japanese macaques and gorillas aligned with my mentor's frameworks. First, I traversed Japan, investigating macaque ecology, sociality, and morphologic variation. Next, Iinvestigated the socio-ecology of gorillas in Africa. I focused on Grauer's gorillas in Kahuzi-Biega National Park (Zaire), and mountain gorillas in Volcanoes National Park (Rwanda). These populations exhibited differences in the prevalence of multi-male groups, female migration patterns, and male group formations. Under the supervision of Dian Fossey in Rwanda, I studied male and group life histories. Following Fossey's tragic death and The movement of Karisoke Research Centre outside the park. I resolved to collaborate with local researchers and engage in community conservation activities. In Kahuzi, I studied the sympatric coexistence of gorillas and chimpanzees in higher and lower regions. They share habitats and diets but adopt different foraging strategies, particularly during periods of fruit scarcity. Early humans adopted a strategy of "turning weaknesses into strengths."This approach enabled us to colonize diverse environments inaccessible to other primates. Modern society has shifted toward a strategy of "amplifying strengths" through technology, leading to significant degradation of the environment. Field studies of nonhuman primates can shed light on the nature and origins of human societies. Continuation of field research is crucial for envisioning and shaping a prosperous future for humanity.

Understanding activity time budgets is crucial for analyzing primate behavioral variability and adaptation to environmental changes. Given the close interaction between wildlife and humans, conservation and management efforts must consider these phenomena. This study investigated the diurnal activity budget and diet of the olive baboon (Papio anubis) in and around the Chato Natural Forest in Oromia region, Ethiopia. We focused on two troops, namely the Bareda troop (inhabiting marginal areas of the forest where human interference is high) and the Dukko troop (occupying the central area of the forest, with little human disturbance). We used scan sampling to collect data on diurnal activity patterns and dietary regime. Bareda troop spent most of their time feeding, followed by resting, and then moving. Dukko troop also spent most of their time feeding, although less than the Bareda troop, followed by resting and moving. Fruits were the primary food source, comprising 53.4-72.7% of Dukko troop's diet and 33-54.4% of Bareda troops. Leaves constituted the second most significant dietary component, being consumed 8.7-16.3% and 20.9-39.6% of the time by the two troops respectively. Human encroachment alters baboon behavior and activity patterns, increasing competition for resources and heightening conflicts with humans. To promote better human-wildlife coexistence, efforts should focus on minimizing, human interference in natural primate habitats, allowing the animals to thrive and reducing conflict with human.

Camera traps are powerful tools that facilitate ecological monitoring and behavioral observations of non-human primates. Although supposedly non-intrusive, some models generate sound and illumination that elicit behavioral responses from different species. Reactions of primates to camera traps are poorly documented, including those of tarsiers, despite their distinctive auditory and visual specializations. Here, we described the reactions of wild Philippine tarsiers (Carlito syrichta) to camera traps based on existing video records on Leyte Island (N = 12) and characterized the light and sound emissions of the camera traps used for recording. We observed avoidance, attraction, and inspection behaviors from the tarsiers after their looking impulses. Using a spectrometer and ultrasonic acoustic analysis, we found that the camera traps emitted light at predominantly infrared wavelengths with peaks at ca. 850 nm (low glow) and ca. 930 nm (no glow). Some low-glow models produced a faint red glow during recording and a detectable clicking sound upon trigger, whereas the no-glow camera traps emitted infrared light with significant ultraviolet components. Based on spectral sensitivity approximations and audible threshold assessments, we found that the emissions of the camera traps are detectable, not only to tarsiers but also other primate species. Our findings suggest that camera traps influence the behavior of tarsiers. Hence, we advise caution when using camera traps since behavioral reactions may induce bias depending on the framing of studies. We also recommend proper planning when accounting for these behaviors, selecting camera trap models, and designing camera trapping studies.