Primates最新文献

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.

Metacognition, the ability to monitor and control one's own cognitive processes, has long been considered a hallmark of human cognition. However, two decades of research have provided compelling evidence of metacognitive-like abilities in some nonhuman primates. This review synthesizes current knowledge on the subject, highlighting key experimental paradigms and empirical findings, with an emphasis on the latest studies. Thanks to advances in methods and efforts to counter alternative explanations, there is now a consensus that great apes and some macaque species can monitor and control some of their cognitive processes. Despite numerous investigations, however, whether capuchin monkeys are metacognitive remains unclear. Critical gaps persist in our understanding of metacognition across species. We discuss the importance of expanding research to include a wider range of primate species and the potential role of ecological factors in shaping metacognitive capacities. In addition, we consider some promising avenues for future research, including neurophysiological approaches, studies of metacognitive errors, and field experiments.

In many primate species, nest raiding is a form of opportunistic foraging behavior designed to acquire protein-rich eggs and nestlings. In urban environments, this is a significant cause of nest failure in birds. Here, we describe nest raiding and egg predation in bonnet macaques (Macaca radiata) inhabiting a suburban area of Salem, Tamil Nadu, India. During nest raiding, large-billed crows (Corvus macrorhynchos) and house crows (Corvus splendens), actively defended their nest from the macaques. When several macaque foragers jointly raided the nest, they were successful in obtaining and consuming the eggs. In contrast, when a solitary macaque attempted to raid the nest, it was unsuccessful. Bird size appeared to play an important role in nest defense. Small birds, such as the scaly breasted munia (Lonchura punctulata) and the purple sunbird (Cinnyris asiaticus) were not able to protect their nests from lone bonnet macaques. These observations indicate that in urban landscapes, bonnet macaques are egg predators of many bird species. When macaques coordinate their actions and forage in small subgroups, they were more successful in preying on the eggs of larger-bodied bird species.

There is little information on maternal behaviour that deprives offspring of food, but some Japanese macaque, Macaca fuscata, mothers have been observed to snatch food from their offspring and eat it. This study investigated maternal food snatching behaviour (MFSB) and its impact on the growth of their offspring in provisioned, free-ranging Japanese macaques. The amount of food a mother snatched from her offspring was estimated to be 51.2% by dry weight compared to the amount of solid food an infant of the same age took in. Body mass growth of affected infants indicated a below-average mass gain. The study suggests that MFSB might be a pathological behaviour and provides the first detailed account of parental exploitation in animals.

Female crested gibbons (genus Nomascus) perform conspicuous sequences of twitching movements involving the rump and extremities. However, these dances have attracted little scientific attention and their structure and meaning remain largely obscure. Here we analyse close-range video recordings of captive crested gibbons, extracting descriptions of dance in four species (N. annamensis, N. gabriellae, N. leucogenys and N. siki). In addition, we report results from a survey amongst relevant professionals clarifying behavioural contexts of dance in captive and wild crested gibbons. Our results demonstrate that dances in Nomascus represent a common and intentional form of visual communication restricted to sexually mature females. Whilst primarily used as a proceptive signal to solicit copulation, dances occur in a wide range of contexts related to arousal and/or frustration in captivity. A linguistically informed view of this sequential behaviour demonstrates that movement within dances is organized in groups and follows an isochronous rhythm - patterns not described for visual displays in other non-human primates. We argue that applying the concept of dance to gibbons allows us to expand our understanding of communication in non-human primates and to develop hypotheses on the rules and regularities characterising it. We propose that crested gibbon dances likely evolved from less elaborate rhythmic proceptive signals, similar to those found in siamangs. Although dance displays in humans and crested gibbons share a number of key characteristics, they cannot be assumed to be homologous. Nevertheless, gibbon dances represent a striking model behaviour to investigate the use of complex gestural signals in hominoid primates.