Primates最新文献

Fat-tailed dwarf lemurs (Cheirogaleus medius), primates endemic to Madagascar, are obligate hibernators that form stable, lifelong pairs in the wild. Given the temporal constraints imposed by seasonal hibernation, infant dwarf lemurs must grow, develop, and wean within the first two months of life. Maternal as well as paternal infant care, observed in the wild, has been deemed critical for infant survival. Given the importance of fathers' involvement in early infant care, we expect this behavior to persist even under captive conditions. At the Duke Lemur Center, in Durham NC, we observed two families of fat-tailed dwarf lemurs and focused on the behavior of adult males within the first two months of the infants' lives. We report evidence of paternal involvement, including babysitting, co-feeding, grooming, accompanying, and leading infants, consistent with observations from the wild. As expected, paternal babysitting decreased as infants gained independence, while co-feeding increased. Supplemental anecdotes, video recorded by observers, also highlight clear cases of involvement by both parents, and even older siblings, in safeguarding and socializing new infants. We argue that maintaining captive fat-tailed dwarf lemur populations under socially and ecologically relevant conditions facilitates the full expression of physiological and behavioral repertoires. Most importantly, it also allows dwarf lemurs to realize their species' potential and become robust proxies of their wild kin.

The small apes, gibbons and siamangs, are monogamous species with their social groups comprising of both parents and their offspring. Therefore, the loss of a member may elicit a stress response in the remaining members due to their strong bonds. Glucocorticoids (GCs) have been useful indicators of stress, but distinguishing between acute versus chronic stress may be limited when measuring these hormones alone. The adrenal hormone dehydroepiandrosterone-sulfate (DHEAS), a GC antagonist, has been implicated in the regulation of the stress response. Thus, the concomitant measurement of these hormones can help examine whether an event, such as the loss of a group member, elicited a stress response. In this brief report, we discuss the hormonal response of two zoo-housed northern white-cheeked gibbons (Nomascus leucogenys) (1 adolescent male and his mother) after the death of the adult male of the group. Baseline fecal samples were collected opportunistically from these two individuals 5 months prior, and 3 months following the death of their group member. A total of 25 samples were quantified for fecal GC metabolites (FGCMs) and DHEAS by enzyme immunoassay (EIA) to calculate the FGCMs:DHEAS ratio. Our results indicate an increase in FGCMs and FGCMs:DHEAS for the adolescent male, but not the adult female, following the death. Our findings suggest that the integration of FGCMs and DHEAS measurements can provide valuable information to interpret individual stress levels to the sudden change in the group's social structure.

Activity budget analyses are important for understanding how animals spend their time in daily activities like resting, foraging, moving and socializing. These behaviors are closely linked to energy management, so habitat quality and resource availability are known to influence the activity budgets of species. Therefore, many studies have examined the consequences of habitat loss and fragmentation on the energetic demands and activity budgets of species. However, we still have limited knowledge of how animals behave in large, continuous, and protected environments, as such habitats are currently rare. The present study analyzed how temporal variation, age, sex and reproductive status influenced the activity budget of wild red howler monkeys (Alouatta guariba clamitans), in one of the last Atlantic Forest remnants that remains large and protected. Between November 2017 and December 2018, we monitored two groups, G3 and G4, in Parque Estadual Carlos Botelho, São Paulo, Brazil. The groups were composed of one adult male, two adult females and their offspring and one (G3) or two (G4) subadult males, using scan sampling for behavioral for data collection every 20 min. The most common behavior was resting, followed by foraging, moving and social interactions, with inter-group differences. Temporal variation explained most of the fluctuations in the activity budget, so did age and sex, but to a lesser degree. The reproductive status of females did not alter their activity budget. These findings reveal that even neighboring groups display distinct and intricate relationships with their habitat. Future studies should be conducted in continuous forests to determine what is the expected range of variation in activity budget, particularly in those species considered as flexible and inhabiting endangered habitats, such as the Atlantic Forest.

There are more than 200 species and subspecies of Neotropical Primates of which more than 40% are listed as threatened by the IUCN Red List of Threatened Species. Both in situ and ex situ conservation programs can benefit from the use of assisted reproductive technologies. The objective of this study was to evaluate, for the first time, cryopreservation techniques for Alouatta caraya semen. Semen samples were collected from five adult males, analyzed, and frozen in either Test-egg yolk or Test-soy lecithin-based extenders containing either 3 or 4% glycerol. Frozen-thawed samples were analyzed at 10, 40, and 80 min post-thaw. Egg yolk-based extenders were overall better than soy lecithin-based extenders. There was no significant difference between 3 and 4% glycerol in any of the parameters analyzed, however, 4% glycerol in egg yolk-based extender produced more favorable results for total motility, intact plasma membrane, lipid peroxidation, and DNA fragmentation index. This study brought novel information on semen characteristics and cryopreservation aspects for A. caraya, which can help shape future experiments to improve the outcome of frozen-thawed sperm for this and other species of Neotropical primates.

Individual identification plays a pivotal role in ecology and ethology, notably as a tool for complex social structures understanding. However, traditional identification methods often involve invasive physical tags and can prove both disruptive for animals and time-intensive for researchers. In recent years, the integration of deep learning in research has offered new methodological perspectives through the automatisation of complex tasks. Harnessing object detection and recognition technologies is increasingly used by researchers to achieve identification on video footage. This study represents a preliminary exploration into the development of a non-invasive tool for face detection and individual identification of Japanese macaques (Macaca fuscata) through deep learning. The ultimate goal of this research is, using identification done on the dataset, to automatically generate a social network representation of the studied population. The current main results are promising: (i) the creation of a Japanese macaques' face detector (Faster-RCNN model), reaching an accuracy of 82.2% and (ii) the creation of an individual recogniser for the Kōjima Island macaque population (YOLOv8n model), reaching an accuracy of 83%. We also created a Kōjima population social network by traditional methods, based on co-occurrences on videos. Thus, we provide a benchmark against which the automatically generated network will be assessed for reliability. These preliminary results are a testament to the potential of this approach to provide the scientific community with a tool for tracking individuals and social network studies in Japanese macaques.

Platyrrhines consume many species of arthropods in the order Orthoptera. Some species of orthopterans can produce chemical defenses that render them toxic or unpalatable and thus act as predator deterrents. These species include the stick grasshoppers (family Proscopiidae), which are widely distributed in the Caatinga biome in northeastern Brazil, which comprises part of the distribution of capuchin monkeys. Capuchin monkeys are omnivores and consume a wide variety of foods, including unpleasant-tasting, potentially toxic items, which they need to learn how to process. We describe the processing of stick grasshoppers (Stiphra sp.) by wild capuchin monkeys (Sapajus libidinosus) that live in Serra da Capivara National Park, Brazil, and compare how individuals of different age classes handle these potentially toxic food items. S. libidinosus predominantly avoided consuming the digestive tract, which contains toxic compounds, when feeding on stick grasshoppers. Immatures took longer than adults to process the stick grasshoppers, indicating that capuchins need to learn how to process the toxic digestive tract of these prey to avoid consuming it.

The survival of limb-disabled primates in the wild has been widely reported. Nevertheless, their ultimate fate is little documented. It is important to understand the influence of limb disability on primate survival from a conservation perspective, as many African great apes suffer from limb injuries caused by entrapment in snares. Here, we report the death of a one-armed blackback male in a large one-male group of wild western lowland gorillas. The subject was a blackback male (14 years old) named Dodo, who lost his right forearm in August 2008. On 8 December 2019, Dodo was found to have suffered serious bleeding injuries to the front of his body, including large lacerations and puncture wounds. On 14 December his corpse was found in the forest. We provide evidence to suggest that his injuries were more likely caused by intraspecific aggression, though a predatory attack by a leopard could not be completely ruled out. His one-armed disability could have made him more vulnerable to attack from either a gorilla or leopard and led to his fatal injury. This report shows that a gorilla who had previously overcome a disability in one arm in childhood may die prematurely, in part, owing to this disability in young adulthood.

Although chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) share a multi-male/multi-female societal organization and form male-philopatric groups, disparities in terms of male aggression and stability of temporary parties are thought to exist among them. However, existing research in bonobos has mainly focused on the high social status, prolonged receptivity, and characteristic sexual behaviors of females, leaving the behaviors of males understudied. Moreover, prior comparative studies on Pan suffer from methodological inconsistencies. This study addresses these gaps by employing a uniform observation method to explore party attendance and aggressive interactions among male bonobos in Wamba and male chimpanzees in Kalinzu. Unlike male chimpanzees, which exhibit dispersion in the absence of receptive females in the group, male bonobos showed a lesser degree of such dispersion. Although the overall frequency of aggressive interactions per observation unit did not significantly differ between the two species, the nature of these interactions varied. Notably, severe aggressive behaviors such as physical confrontations among adult males were absent in bonobos, with most aggression occurring between the sons of the two highest-ranking females. Additionally, in bonobos, females actively engaged in polyadic aggressive behavior as aggressors, while all instances of coalitionary aggression in chimpanzees originated from male aggressors. These findings underscore the substantial impact of female behaviors on the observed distinctions in male aggressive interactions between the two species.

Wild chimpanzees (Pan troglodytes) are caught in snares set for other animals and sometimes injure or lose body parts. Snaring can compromise the health, growth, survival, and behavior of chimpanzees and, thus, represents a threat for the conservation of this endangered species. During a long-term study of chimpanzees at Ngogo in Kibale National Park, Uganda, we started a project to remove snares in and around their territory. We compared the number of times chimpanzees were snared during the 12.75 years after the start of this project with the number of times individuals were snared during the previous 14 years. Only one chimpanzee was snared after we began removing snares compared with 12 individuals caught during the period before. This represents a clear reduction in the risk created by snaring at this site and suggests that removing snares can be employed to protect chimpanzees.