Primates最新文献

In 1986, Japanese macaques of the Arashiyama B group fissioned, with high-ranking females forming the dominant E group and the middle- and low-ranking females forming the subordinate F group (Suzuki et al. in Primates 64:79-90. https://doi.org/10.1007/s10329-022-01024-x , 2023). In 1988, we recorded the dominant-subordinate interactions among adult females in both groups and analyzed them to clarify how they reorganized their dominance relations. The two groups showed contrasting results. Two years after group fission, the past dominance relations among female kin-groups had been largely maintained in E group, whereas the dominance relations among females in F group had been significantly reorganized, with the females from some kin-groups dispersing into various rank positions within the group. In both the E and F groups, the kin-related dyads within the 2nd degree of maternal relatedness (consanguinity) (r ≥ 0.25) tended to follow Kawamura's principles (Kawamura in Primates 1:149-156, 1958), but a considerable number of dyads did not. Such deviations from the principles seemed to derive from multiple factors: past rank reversals between the mothers and daughters, social influences from high-ranking males, and changes in the membership of kin-related females following group fission; for example, disappearances of or separations from mothers. Once rank changes were fixed, however, the relations of the newly emerged mother-daughter and sister dyads again reflected Kawamura's principles.

Social connections within primate groups are continuously changing, and an individual's connectedness within their social network can have important consequences on morbidity and mortality. Here, we examined the effects of early life social experiences and age on social connectedness of captive female olive baboons (Papio anubis). Subjects included 54 mother-reared (MR) and 35 nursery-reared (NR) baboons (4.03 to 19.8 years of age). We conducted four 15-min focal observations and recorded all social interactions. For every possible dyad, we calculated total amount of time in proximity to one another and total amount of time spent grooming (in each direction), then used these data to create interaction matrices. We then calculated a number of direct and indirect measures of social connectedness in UCINET. Direct measures included degree centrality for grooming and proximity. Indirect measures included beta centrality for grooming and eigenvector centrality for proximity. A MANCOVA examining the effects of rearing on the three measures of direct connectedness: (1) in-degree and (2) out-degree centrality for grooming, and (3) degree centrality for proximity revealed an overall significant rearing effect, with age as a significant covariate. Subsequent univariate analyses revealed significant rearing effects on grooming out-degree centrality, in which MR females groomed conspecifics at significantly higher frequencies than NR females. There were no significant rearing effects on grooming in-degree centrality, proximity degree centrality, or any of the indirect social connectedness measures. One possible interpretation of these effects is that NR baboons might not find grooming to be intrinsically rewarding, and therefore have less motivation to groom others. Contrary to our predictions, older females did not have significantly fewer social partners, nor did they spend less time engaging in social interactions, compared to younger females. Overall, the results of this study suggest that among female baboons, early life social experiences affect social connections into adulthood, while age appears to explain less of the observed variation in social connectedness.

Compared with wild troops, Japanese macaques (Macaca fuscata), which are commonly housed in cage-like enclosures in zoos and laboratories, face limited feeding opportunities, leading to intense competition and frequent aggression. Such aggression often results in injuries, highlighting the need for methods to reduce aggression in captive settings to improve welfare. This study evaluated the effects of three enrichment strategies-fire hoses with branches, external feeders, and plastic tubs with straw-designed to promote spatial usage and diversify feeding opportunities in a Japanese macaque group in Hirosaki City Yayoi Ikoi Park. The frequency of aggressive behavior and spatial utilization across vertical cage layers was recorded. Generalized linear models revealed that all the tested enrichments significantly reduced intense aggressive and displacement behaviors. Fire hoses increased the usage of the second layer, whereas external feeders and plastic tubs decreased the usage of the top layer, which was used most in the control condition, promoting group dispersion. These interventions improved the environmental opportunity and choice (environmental domain of the Five Domain model), decreased aggression-related injuries (physical health domain), encouraged to express natural behaviors such as climbing and foraging (behavioral domain), and reduced fear and discomfort due to the proximity of dominant individuals (mental domain), collectively supporting enhanced welfare.

Global climate change is directly influenced by human actions due to land use and occupation. In this way, factors related to environments conditions, concomitant with anthropogenic impacts, determine the suitability of environments for species. We analyze the present-day and future suitability of environments for Saguinus martinsi, a primate species endemic to the Brazilian Amazon region. We analyzed two different greenhouse gas emission scenarios, known as Shared Socioeconomic Pathways (SSPs), one "optimistic" (SSP2-4.5) and the other "pessimistic" (SSP5-8.5), described by the Coupled Model Intercomparison Project. We created the models using climatic, edaphic, and topographic variables based on the Euclidean Distance algorithm. Our results indicate that S. martinsi may face severe threats in the near future as a consequence of climate change, given that no environmentally suitable areas were identified for the species in either of the future climate scenarios analyzed. We understand that it is necessary to expand searches for the presence and/or absence of the species in potentially environmentally suitable areas, in addition to consolidating measures to mitigate environmental impacts for the conditions found.

Social play requires communicative abilities that start developing since the first phases of life. Due to their paedomorphic nature, bonobos (Pan paniscus) tend to maintain a playful attitude also in adulthood. Here, we present the case of an adult bonobo (Congo) that has never had any contact with conspecifics in the first 40 years of life. In 2023, Congo underwent an introduction protocol at the Wilhelma Zoo. Prior to the data collection period, he had spent 8 months within the group. The aim was evaluating Congo's playful social competence and his ability to react in a resilient way to others' stimuli. The play sessions involving Congo and two juveniles (CPSs) were compared with play sessions occurring in other adult-juvenile pairs (OPSs). Compared to OPSs, CPSs were shorter and more punctuated by grooming pauses that were totally absent during OPSs. Despite increased grooming, CPSs had a higher risk of escalation into overt aggression from Congo frequently screaming during the interaction. Unlike other adults, Congo never rapidly replicated the partners' playful facial displays, a phenomenon known as rapid facial mimicry. Despite Congo appearing to struggle to manage social play, he responded to other's invitations, thus indicating a presence of play motivation. Albeit being just a case report, our findings emphasize the importance of adult play as a mechanism for social integration, even in individuals entirely unfamiliar with its nuances. Although animals engage in play early in life, it is never too late to play the game and strengthen social bonds.

In primates, mothers are crucial for the survival and integration of young offspring into their social group. Usually, mothers adjust their behaviour to the offspring's age and needs, but maternal experience might modulate developmental changes in such allocation. In this study, we conducted behavioural observations on 7 mother-offspring dyads of captive western lowland gorillas (Gorilla gorilla gorilla) to assess whether multiparous mothers adjusted to the changing requirements of their offspring differently from primiparous mothers, and better facilitated their social integration into the group. Our results showed that, compared to primiparous mothers, multiparous mothers were more likely in body contact with younger offspring and less with older offspring. However, maternal experience neither predicted nor mediated how likely mothers were to start or end body contact, nor did it mediate developmental changes in the offspring's social behaviour toward other group members. Our study provides preliminary evidence of some limited differences in how primiparous and multiparous mothers allocate maternal behaviour in western lowland gorillas.

Predation influences foraging strategies, as primates must avoid being preyed on while feeding. Some populations of capuchin monkeys are the only neotropical primates that customarily use the ground for nut-cracking. This time-consuming and focus-demanding foraging activity may increase susceptibility to predation events. However, there is currently no data on predation in tool-using Sapajus populations. We report a snake's (Boa constrictor) predatory attack on a bearded capuchin monkey (S. libidinosus) in a tool-using population, as well as the other monkeys' alarm calling and threat displays. We confirm these monkeys' predation vulnerability and discuss how they balance foraging requirements with predation risk.

Muriquis (Brachyteles sp.) are endemic to the Brazilian Atlantic Forest; its genus is divided into two species, the northern muriqui (Brachyteles hypoxanthus), and the southern muriqui (Brachyteles arachnoides), both assessed as Critically Endangered by the IUCN Red List. The endangered status of muriquis is associated with habitat loss, fragmentation, hunting, and other anthropogenic actions, confining the species to fragments, mostly, in protected areas. One of these important protected areas is in the Serra da Mantiqueira, the Environmental Protection Area Serra da Mantiqueira, that has a sizable continuous remnant of the Atlantic Forest with a high degree of biological diversification, where both species of muriquis occur. This designation highlights the region as one of the most critical regions for the genus Brachyteles. Nonetheless, new records may fill gaps in the distribution limit between the two muriquis species, identifying whether there is a possible barrier or possible overlapping area. However, recording and estimating primate populations over large areas through standard field techniques, such as linear transects, can be costly in terms of time and financial resources. In addition, given its altitude gradient, the Serra da Mantiqueira region is remote and difficult to access for systematic biodiversity surveys. Thus, aerial surveys were carried out using thermal sensors attached to drones, which made it possible to record two new groups of southern muriquis in Serra da Mantiqueira. Thus, we confirm that this new method represents an effective way to survey highly threatened primates.

This report documents the predation of Macaca cyclopis (Taiwanese macaque) on the flying adults of ground-nesting leaf-cutting bee, Trachusa formosanum. With observations and video recordings of an incident in the wild, we detail how adult and juvenile macaques capture and consume bees during their flight, with varying success rates. Seizing the correct timing when the bees fly low to approach their nests is the key skill for bee hunting. This predation occurs during the breeding season of T. formosanum, when the bees' nests are spatially concentrated, making them a spatially and temporally predictable food source for the macaques. The findings highlight that M. cyclopis do exploit seasonal high-protein food resources, and provide new insights into their dietary habits, with potential implications for understanding foraging-relevant social learning in primates. Further studies are needed to explore the potential nutritional significance of this behavior and its role in macaque reproductive strategies.