Primates最新文献

Leucism, a pigmentation disorder resulting in partial loss of coloration, is rare in neotropical primates. This manuscript presents the first report of a leucistic robust capuchin monkey (Sapajus libidinosus), observed at Ubajara National Park, Brazil. Our findings contribute to the sparse literature on leucism in New World monkeys, emphasizing the importance of long-term studies for monitoring such rare anomalies.

The Philippine tarsier (Carlito syrichta) is a small non-human primate endemic to the Greater Mindanao Faunal Region of the Philippines. It is classified as a specially protected faunal species under national wildlife conservation laws. However, studies on local communities' knowledge and understanding of the Philippine tarsier remain limited. Gaining insights into the scope and nature of this local knowledge is essential for improving public perceptions and attitudes toward the species' cultural and wildlife values. To address this gap, an in-person household survey was conducted from March to April 2023 in Biliran, Philippines, to assess species literacy among 420 residents, focusing on both broad and specific knowledge of the Philippine tarsier using photo identification and a 10-item True or False test. The findings revealed that while the respondents were generally familiar with the species, they demonstrated only a moderate level of specific knowledge and limited awareness of its natural presence on the island. Among the sociodemographic variables, age, educational attainment, years of formal education, and residence location and duration showed significant association with knowledge level, while education level and years of education showed a significant increasing trend with species familiarity. Widespread misconceptions were identified regarding the Philippine tarsier's feeding habits (beliefs that it consumes fruits and charcoal), natural distribution (the belief that it is found only in Bohol), and self-injurious behavior (the myth that it commits suicide). Through targeted information campaigns, correcting these inaccuracies is vital to strengthening local knowledge, which, in turn, can help promote the proper treatment of the species and foster more informed attitudes and stronger support for the conservation of the Philippine tarsier and its habitat.

Environmental changes, such as transfers and social introductions, can be major sources of stress in wild animals. Monitoring the physiological response through glucocorticoids is an effective tool to assess how animals cope with and adjust to these changes. In this study, we followed the habituation and social integration of Suzie, a former pet and entertainment chimpanzee confiscated and transferred to a primate rescue center. Our objectives were to (1) monitor her fecal glucocorticoid metabolite (FGM) levels throughout rehabilitation, and (2) investigate how association-related factors (e.g. number of individuals, ages of association partners) influenced her FGM levels and social behaviors during associations with the resident chimpanzees. A total of 169 fecal samples from Suzie were collected over 10 months and quantified using enzyme immunoassay, along with 38 opportunistic samples from the resident chimpanzees. During association sessions, data on aggressive and affiliative events were recorded. Suzie's FGM levels ranged from 11.01 to 113.04 ng/g of feces. After a four-month adjustment period (118 days) before returning to basal hormone activity, her FGM concentrations aligned with individual mean levels of the resident chimpanzees (range: 24.19 ± 7.99 to 29.69 ± 8.93 ng/g of feces). The presence of a broker individual during associations impacted the likelihood of affiliative events (p < 0.01). Furthermore, early social housing conditions of the resident chimpanzees influenced social dynamics, with affiliative behaviors being more likely to occur while interacting with individuals who were housed in social groups during infancy, and aggressive events being more likely to occur while interacting with those housed alone (p < 0.05). Our findings underscore the value of non-invasive hormone monitoring and behavioral assessments to better understand individual experiences.

The howler monkeys (Alouatta) are part of the Platyrrhini infraorder, a group of Neotropical primates with the widest geographical distribution, occurring from southern Mexico to northern Argentina. Previous phylogenetic studies based on cytogenetic, morphological, and molecular data have shown inconsistent results, requiring new approaches to clarify relationships within the genus. In this study, we analyzed nine species of Alouatta using 24 molecular markers (2 mitochondrial and 22 nuclear genes). Through Bayesian inference, Maximum Likelihood, and divergence time analyses, we inferred the phylogeny and estimated the timing of speciation events. Our results recovered two major clades within Alouatta, corresponding to Mesoamerican (Trans-Andean) and South American (Cis-Andean) lineages. Most diversification events occurred during the Pliocene. Within the South American clade, we identified two well-supported groups: one composed of species from the Atlantic Forest and eastern Amazon (A. guariba, A. belzebul, and A. discolor), likely shaped by the formation of the South American dry diagonal; and another formed by A. caraya and the A. seniculus complex. Notably, our results confirmed a close phylogenetic relationship between A. discolor and A. belzebul, and between A. macconnelli and A. nigerrima, which occur on opposite sides of the Amazon River.These relationships, along with the confirmation of A. discolor and A. nigerrima as distinct species based on multilocus evidence from known localities, represent advances over previous studies and contribute to a more resolved understanding of Alouatta diversification.

The phenology of trees in tropical forests shapes the temporal distribution of resources such as fruits and leaves. In montane forests (> 1000 m altitude), tree diversity and primary productivity tend to decline with elevation, correlating with lower temperatures and resulting in low food availability for herbivorous and frugivorous consumers. In such environments, wild animals often rely on adaptive food choice strategies to cope when preferred resources are scarce, shifting to less preferred but more available items. This research examines the feeding strategy of red howler monkeys (Alouatta seniculus) inhabiting a montane forest in the Colombian Andes (2,500-3,000 m asl) by analyzing their food intake (grams of dry weight) and their response to resource availability and food species aggregation over an annual cycle. We recorded 1,277 h of continuous focal animal sampling of two howler groups and monitored 28 phenological plots within their home range. Fruit availability varied throughout the year, with asynchronous fruiting patterns observed both within and between species, while leaves remained available all year-round. Montane howlers maintained a predominantly folivorous diet; however, only the daily intake of young leaves and ripe fruits was significantly explained by their availability. Overall, total daily food intake increased with ripe fruit and flower availability but decreased with that of unripe fruits, even though did not explain ripe fruit consumption. In contrast, the aggregation of food species had no effect on daily food intake. Although availability varied among items, montane howler monkeys adjusted their consumption patterns to specific resources availability (e.g., increasing intake of ripe fruits and young leaves during periods of higher availability), within the context of their primarily folivorous feeding strategy.

Japanese macaques at Jigokudani Snow Monkey Park, Nagano, exhibit hot spring bathing behavior (HSBB) during the cold season. HSBB is known to aid thermoregulation and reduce stress, but its impact on host-associated biota in nonhuman primates remains unexplored. In this study, conducted between December 2019 and March 2021, we investigated the relationship between HSBB and lice load, gastrointestinal (GI) parasitism, and the gut microbiome in Japanese macaques at Jigokudani. Fecal samples were collected from sixteen adult females (9 bathers and 7 non-bathers) varying by age, reproductive status, and social rank. Nit-picking rates, used to estimate lice load, differed between bathers and non-bathers in submerged and non-submerged areas. We detected four GI helminths and at least one protozoan parasite, but did not observe noticeable differences in the probability of infection or abundance of these endoparasites between bathers and non-bathers. Finally, the alpha and beta diversity of the gut microbiome did not differ between bathers and non-bathers, but we identified four microbial genera that were significantly more abundant in non-bathers. These findings suggest that HSBB may influence host-(micro)organism relationships. Further research is needed to explore potential health outcomes associated with HSBB.

Diurnal primates show periods of wakefulness at night because of ecological factors, but the degree to which they shift the timing of their activities in response to anthropogenic factors is poorly understood. We aimed to examine whether Geoffroy's spider monkeys (Ateles geoffroyi) are active during the night and evaluate the effects of climatic and anthropogenic factors on their nocturnal activity. We conducted 66 half-night behavioral observations on wild spider monkeys at a known sleeping site in the human-modified habitat of Los Árboles Tulum, Quintana Roo, Mexico between August 2018 and July 2019. We used generalized linear mixed models to test the effects of moonlight intensity, heat index, anthropogenic light, and anthropogenic noise on vocal and non-vocal activity during the night. Diurnal spider monkeys showed some level of activity at all hours of the night within their sleeping site. We found no effect of the predictor variables on the amount of time spider monkeys were non-vocally active, but the number of vocalizations was positively affected by moonlight intensity, heat index, and anthropogenic noise, and negatively by anthropogenic light. Increased moonlight intensity, perceived temperature and noise may disrupt sleeping patterns, leading to more vocal activity, whereas spider monkeys may emit whinnies when they cannot see one another, potentially explaining the negative relationship between the number of whinnies and anthropogenic light. Our findings contribute to the view that diurnal primates may be more flexible in their activity patterns than previously thought and that spider monkeys can adjust to permanent low-level anthropogenic impact and live alongside humans in modified habitats.

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.

Habitat fragmentation poses a significant threat to primate populations, necessitating behavioral adaptations in activity patterns and feeding strategies. This study investigated the impact of habitat fragmentation on the endangered San Martin titi monkey (Plecturocebus oenanthe) in the Moyobamba region of Peru. Activity budgets and feeding strategies were compared between groups inhabiting large (400 ha) and small (5 ha) forest fragments. Results revealed that resting was the predominant activity in both habitats, followed by feeding. Notably, individuals in large fragments allocated significantly more time to feeding (30.1%) than those in small fragments (23.0%) did. Social interactions were more prevalent in the small fragments (15.1%) than in the large fragments (9.1%). Fruit was the primary dietary component in both sites, accounting for 59.9% in the large fragment and 44.9% in the small fragment. However, individuals in small fragments exhibited a higher consumption of leaves (13.7%) and prey (14.6%) than those in large fragments (7.1% and 8.5%, respectively). The feeding time for specific food resources varied according to the fragment size and seasonal availability. These findings demonstrate the ecological plasticity of P. oenanthe in adapting to fragmented habitats by modifying their activity budgets and feeding strategies. However, continued habitat degradation may compromise these adaptive mechanisms, highlighting the need for conservation efforts focused on habitat restoration and connectivity to ensure long-term persistence of this endangered primate species.