Primates最新文献

Huddling behaviour is present in many animal species. This behaviour involves maintaining close physical contact with conspecifics to minimise heat loss and, in general, reduce energy expenditure. Additionally, this behaviour also facilitates complex social interactions within a population. In Japanese macaques, this behaviour is observed in many populations across Japan, including Shodoshima, where huddling clusters can reach up to 100 individuals in winter. Based on several studies on this species, it appears that huddling, or sarudango in Japanese, is influenced by both meteorological factors and social relationships between individuals. The objective of this study is to understand the determinants that drive the expression (presence or absence) and the organisation (number of individuals and identities) of huddling clusters. Two hypotheses were formulated. The first hypothesis posits that the formation and variations in the size and number of clusters are influenced by meteorological factors, while the second hypothesis suggests that the number and position of individuals within a cluster are related to existing relationships between individuals. To test these, data on the number, size, and individuals composing a cluster were collected, allowing building huddling social networks. Simultaneously, meteorological measurements were taken, along with observations on dominance and grooming interactions between individuals. This allowed us to create several statistical models and social networks for comparison. Our results suggest that the probability for observing huddling is mainly related to solar radiation energy, while variations in number and size could be explained by temperature. Moreover, the organisation within a cluster is not random but reflects relationships between individuals. The ones sharing more grooming and having similar dominance ranks have more probabilities to be in the same huddling cluster.

Food supplementation by humans in peri-urban and urban landscapes can lead to excessive intake of energy and certain macronutrients, and affect animal health. In this study, we evaluated the influence of food supplementation on urinary health indicators in brown howler monkeys (Alouatta guariba) by comparing supplemented and non-supplemented free-ranging peri-urban groups. We also evaluated the effect of sex, day shift, and season of sampling. Between August 2021 and August 2022, we non-invasively collected 61 samples (43 from females and 18 from males) from adult individuals (N = 10) in three supplemented groups and 56 samples (25 from females and 31 from males) from adults (N = 7) in three non-supplemented groups. The supplements, mostly raw foods (e.g., fruits, vegetables, and tubers) and bread, represented 18% of the total fresh mass ingested by the supplemented groups. We assessed pH, density, and the presence of eight urine components (glucose, bilirubin, ketones, protein, urobilinogen, nitrite, blood, and leukocytes) using reagent urine strips. Season of sampling predicted urine density (mean = 1.022), while both season and day shift predicted pH (mean = 6.5). The occurrence of supplementation was a weak predictor of these parameters. Finally, we detected leukocytes in 21% of the 117 samples. We did not identify any visible signs of disease in any individual throughout the study and found no clinical changes in urine under the conditions studied. We urge validation of the results with urine strips to facilitate monitoring of the health of howler monkeys living in anthropogenic landscapes in the presence or absence of dietary supplementation.

Knowledge about changes in wildlife populations over time is essential for making informed decisions regarding their conservation. We evaluated the influence of distinct habitat factors on the occupancy of Olalla's titi monkey (Plecturocebus olallae), a Critically Endangered primate endemic to Bolivia. We assessed the presence of titi monkey groups using the playback technique, employing point counts in 582 quadrants of approximately 6.25 hectares. Utilizing single-species and single-season occupancy models, we estimated an occupancy (ψ) of 0.21 and found that the presence of P. olallae groups was positively related to heterogenous plant composition forests which indicates they may be more likely to occur in areas of high floristic diversity. We also found that groups of this already range restricted species do not occur in all the forest coverage within their distributional range. This complements previous considerations regarding the habitat in which P. olallae occurs based on its natural history knowledge and highlights the limited suitable habitat for this species. From our sampling effort, we calculated a power of 81% to detect a population change of 30%, showing the potential of occupancy modeling for population monitoring of P. olallae. Thus, we provide an information baseline that will be useful in further population monitoring actions for the conservation of these endemic Bolivian titi monkeys.

Because of the universal decline in biodiversity, it is important to map and assess the populations of the endangered species, especially those endemic to small regions, in their remaining wild habitats. With the main focus on the distribution and habitat suitability of the endangered lion-tailed macaque, Macaca silenus, we carried out a survey on primates in the Kodagu region of the Western Ghats, an area not properly explored earlier. The survey trails covered a length of 523 km. We encountered 185 groups of primates including 112, 12, 43 and 18 groups of bonnet macaques, M. radiata, lion-tailed macaques, black-footed gray langurs, Semnopithecus hypoleucos and Nilgiri langurs, S. johnii, respectively. The Brahmagiri Hills harbored the northernmost group of Nilgiri langurs and the southernmost group of black-footed gray langurs. Habitat suitability analysis revealed that the distribution of bonnet macaques and black-footed gray langurs was associated with a large number of environmental factors whereas only a few factors each influenced the distribution of other primate species. When considering the whole landscape spanning over 1295 km², black-footed gray langurs (961 km²), bonnet macaques (910 km²) and lion-tailed macaques (779 km²) had more suitable habitats than Nilgiri langurs (258 km²). The reserved forests between two Wildlife Sanctuaries covered an area of 311 km² where 282 km², 228 km², 272 km², and 140 km² areas were found to be suitable for lion-tailed macaques, bonnet macaques, black-footed gray langurs and Nilgiri langurs, respectively. We recommend these reserved forests to be included in the protected area network. The study brings out the Kodagu region to be a potential conservation area not only for the lion-tailed macaques but also for other primate species.

Social support, via investment in relationships of importance with others, is often emphasized as a pathway towards mediating stress. The effectiveness of social support, however, can be altered by personality differences, but the physiological consequences of such covariation are still poorly explored. How do individual differences in the functioning of the stress response system mediate access to, and use of, social support? To examine this dynamic, we investigated glucocorticoids as a biomarker of energetic activation that may also be activated by chronic psychosocial stress. For this purpose, we studied a wild anthropoid primate, i.e. the olive baboon (Papio anubis), for 17 months, in Laikipia District, Kenya. We measured biomarkers of energetic activation, i.e., fecal glucocorticoid metabolites (fGCms), to address whether individual differences in stress coping and social support were associated with variation in hormone levels across a period from 2018 to 2019. We found evidence for an association between social support and fGCm concentrations. This association had a discernable interaction between sex and social support: we found a negative association in male baboons, relative to females-who did not have a pronounced effect. Our findings emphasize the importance of social support in male baboons. The cost of not having diverse bonds, has been downplayed in male baboons.

Infant adoption is an association that occurs between an adult individual and a dependent infant and occurs most often when lactating females care for a nutritionally dependent infant that is not her offspring. Adult females are often involved in adoption; while, direct infant care by males occurs in less than 5% of all mammalian species. We report the first record of adoption by wild male adults of Alouatta caraya, a platyrrhine primate species that does not typically participate in parental care. We observed two independent cases of adoption, in two different groups (G1, G2) at the Corrientes Biological Station, Argentina. After the death of two adult females with dependent infants, one adult male adopted an orphan in each group. We recorded the activity of the adoptive males and the two infants. During this period, adoptive males expressed parental care behaviors toward infants. However, after 38 days in G1 and 53 days in G2, both infants died. Based on our continuous monitoring of study groups, we suggest that adoptive males are the biological parents of the orphaned infants. As such, kin selection may explain the care of the infants. However, another explanation could be group familiarity, which refers to the social bonds and cohesion that develop among individuals within a group, even if they are not genetically related. An adult male, although not genetically related to the infants, may take care of them due to the cohesion and relationships established within the group during his period of residence. The study of these rare parental behaviors taken by A. caraya adult males provide insights into the knowledge of group social cohesion and structure.

Habitat loss due to deforestation is a primary threat to global biodiversity. Clearing tropical rainforests for agriculture or development leads to forest fragmentation. Forest fragments contain fewer large trees and provide lower food availability for primates compared to continuous forests. Mantled howler monkeys (Alouatta palliata) inhabit fragmented rainforests and may need to alter their activity budgets and spatial cohesion to mitigate competition and conserve energy in fragments where food quality is lower. We compared howler monkey activity and spatial cohesion across a small forest fragment (La Suerte Biological Research Station, LSBRS) and a large, continuous forest (La Selva Research Station) in Costa Rica. We predicted that monkeys at LSBRS would rest more, feed more, travel less, and be less spatially cohesive compared to La Selva to contend with fewer resources in the small fragment. Using instantaneous scan sampling at 2-min intervals during 30-min focal samples, we recorded activity and the number of individuals within 5 m of the focal animal. We collected 1505 h of data from 2017-2024. Monkey activity and spatial cohesion differed significantly across sites. As predicted, monkeys at LSBRS spent more time feeding than at La Selva, but contrary to our predictions, they rested less and traveled more. The mean number of individuals within 5 m was significantly lower at LSBRS compared to La Selva. The ability to modify their activity and spatial cohesion in response to fragmentation provides insight into how primates can contend with fewer resources and higher competition in changing ecosystems worldwide.

Information on the life histories of male macaques after leaving their natal troops is limited. A solitary male Japanese macaque (Macaca fuscata), estimated to be 5 years old, appeared in the urban area of Ishinomaki City, Miyagi Prefecture, northern Japan, where no troops are distributed, in May 2023. Because the animal was habituated to and fed frequently on garden crops, it likely came from the western part of the prefecture, where multiple crop-feeding troops are distributed. The male stayed in the hilly area in the central part of the city until June and then moved north in July. The male moved south to the tip of the Oshika Peninsula and returned to the urban area in August, after which the location of the male was unknown. This study demonstrated that (1) male macaques can move > 40 km from their natal troop, (2) the daily travel distance (average: 0.9 km) of solitary males was similar to that of troop animals, whereas the home-range size of solitary males was much bigger than that for single animals, and (3) the home-range location of solitary males changes quickly. These results implied that solitary males in novel environments prioritize finding new troops to join. Our study sheds light on aspects of male life history after dispersal.

Primate populations are under threat due to human activities, like illegal trafficking, requiring conservation efforts such as reintroduction programs. However, these initiatives often encounter challenges, such as aspects of individual behavior related to movement and foraging. The presence of experienced conspecifics has been suggested to improve the success of these programs. This study focuses on woolly monkeys and examines how the presence of experienced conspecifics influences the performance of reintroduced individuals. Focal animal sampling was used to collect data on proximity, diet composition, home range, and use of vertical strata of three groups of reintroduced woolly monkeys. Data was analyzed for the first 2 and 6 months after release of individuals. The results reveal that the involvement of experienced conspecifics speeds up the process of adaptation, particularly in terms of diet diversity and spatial utilization; however, differences in individual responses were also prevalent. Our findings highlight the importance of incorporating individuals with prior wild experience into reintroduction groups for improving the likelihood of success. Additionally, the study underscores the role of social learning in captive management practices, aiding in post-release behavioral adaptation and survival. This research offers valuable insights for primate conservation, emphasizing the significance of considering the presence of experienced individuals and possible social learning processes in the planning and execution of effective reintroduction efforts.

Capuchin monkeys are omnivorous platyrrhines with a high frequency of faunivory and can survive in urban forest fragments. Predation of wild vertebrates (high-quality foods) by capuchin monkeys has been frequently reported in many species of Cebus and Sapajus. However, predation of domestic animals is unknown. We describe a rare episode of predation, consumption, and sharing of an adult domestic chicken (Gallus gallus domesticus) by individuals from a social group of robust capuchin monkeys (Sapajus sp.) living in a small urban park in the city of Foz do Iguaçu, southern Brazil. This relatively large prey is freely farmed at the study site. The capture, slaughter, preparation (removal of feathers from the body), and consumption of the prey by the capuchins lasted 22 min. The dominant adult male ate the chicken's head and tolerated the approach of two juveniles. The juveniles shared the remainder of the prey after the adult abandoned it. These juveniles scared other group members that approached the carcass. We recorded an opportunistic hunt for easily accessible domestic prey, a case of human resource use by urban primates that shared passively the atypical and valuable food. Though a rare event, the predation on a domestic animal indicates a potential source of conflict with humans that can have negative impacts on urban primates.