Primates最新文献

In this paper, I chronicle the Strasbourg population of Tonkean macaques (Macaca tonkeana) over a period of half a century. In 1972, Tonkean macaques were imported from Sulawesi, Indonesia, to eastern France, leading to the establishment of two social groups in the Strasbourg region several years later. Our research team studied the social behavior and cognitive abilities of these Tonkean macaques for four decades. The species is characterized by a high degree of social tolerance. This has proven to be very informative in comparative studies of macaque social behavior, opening a new perspective on the evolution of primate societies. Over the years, the population has grown, and more social groups have been formed. However, the fact that some of the Tonkean macaques were healthy carriers of the herpes B virus led to disagreements over their management and eventually to the elimination of the positive individuals. Many individuals from the Strasbourg population are now kept in sanctuaries, and the number of captive breeding groups is limited. We still have much to learn about Tonkean macaques and there is a need for studies carried out in their native habitat in Sulawesi.

We observed a zoo-housed group of cotton-top tamarins (Saguinus oedipus) before and after a bout of severe targeted aggression directed towards two of its members. The aggression was so severe and repeated that the zoo personnel was forced to remove the two victims and the main aggressor. In the tense period that preceded removal, the tamarins showed increased aggression, a steeper and linear dominance hierarchy, and reduced post-conflict reconciliation compared to the period following removal. In contrast, affiliative interactions such as grooming and peaceful food transfers did not differ in the two periods of observations. Patterns of reciprocity also remained stable. These results highlight the flexibility of tamarin social relationships and provide useful information for managing captive colonies and improving animal welfare.

Sakis (genus Pithecia) are frugivorous primates with a preference for seeds that complete their diet with leaves and insects. Fruit pulp and seeds are known to have different nutritional characteristics that change during the process of ripening. The consumption of seeds can be an adaptation to changes in resource availability, as unripe seeds are a more steadily available resource than ripe pulp or young leaves. Here, we present the first study of the feeding ecology of monk sakis (Pithecia monachus). We investigated dietary composition and identified important feeding plants in a seasonally flooded forest within the Área de Conservación Regional Comunal Tamshiyacu-Tahuayo in Peruvian Amazonia. Throughout 20 months, we followed groups of monk sakis by foot and canoe and recorded 459 feeding events. Seeds were the most frequently consumed food item (49%), followed by pulp (mesocarp, pericarp or aril; 25%) and arthropods (22%). Leaves, bark, and flowers were ingested only sporadically. The importance of ripe seeds and arthropods in the diet of the monk sakis differed from other studies: we recorded the consumption of mostly ripe seeds and the share of arthropods was relatively high.

Cooperative behaviors among individuals of numerous species play a crucial role in social interactions. There is a special interest in investigating the occurrence of cooperation among apes because this knowledge could also shed light on evolutionary processes and help us understand the origin and development of cooperation in humans and primates in general. Gibbons are phylogenetically intermediate between the great apes and monkeys, and therefore represent a unique opportunity for comparisons. The aim of the present study was to discover whether or not white-handed gibbons (Hylobates lar) show cooperative behaviors. In order to test for the respective behaviors, the gibbons were presented with a commonly used experimental cooperative rope-pulling task. The gibbons in this study did not exhibit cooperative behaviors during the problem-solving task. However, prior training procedures could not be fully completed, hence this project constitutes only the onset of exploring cooperative behaviors in gibbons. Additional behavioral observations revealed that the gibbons spent significantly more time "out of arm's reach to everyone", suggesting that they are less often involved in social interactions, than other, more cooperative primates.

Studying the diet and feeding behavior of primates is essential to understanding their ecology and designing effective conservation plans. Despite decades of study on the hamadryas baboon (Papio hamadryas) in lowland habitats, little is known about the feeding ecology of this species in highland ecosystems. To address this empirical gap, we tracked temporal changes in vegetation abundance and their relation to the dietary choices of hamadryas baboons in highland habitat at Borena-Sayint National Park (BSNP) in northern Ethiopia. We performed behavioral scan sampling on a focal study band of 21-37 hamadryas baboons over a 12-month period. We found that mature and young leaves were the most abundant plant parts throughout the year, while fruits and flowers were the least abundant, with significant seasonal variation that followed the bimodal pattern of rainfall characteristic of the Ethiopian highlands ecosystem. The annual diet of hamadryas baboons at BSNP consisted mostly of fruits (32.0%) and graminoid blades (21.2%), and included 52 food species across 22 families of plants and three families of animals. Food raided from nearby farms accounted for 8.8% of their diet. The availability of fruits and flowers was positively correlated with their consumption, suggesting that these are preferred foods, whereas graminoid blades, and other leaves, appeared to be less preferred foods. The feeding ecology of hamadryas baboons at BSNP differs considerably from that of lowland populations. The well-studied lowland hamadryas baboons in Awash National Park obtain much of their diet from Acacia species and palm fruit, whereas those at BSNP, where Acacia trees are rare and palms are absent, relied on Olinia rochetiana and Rosa abyssinica for a combined 27% of their annual diet. The reliance of hamadryas baboons at BSNP on cultivated crops for nearly one-tenth of their diet leads to conflict with humans and warrants more detailed study so that this issue can be addressed in conservation plans for the area.

Comparative thanatology includes the scientific study of death in non-human animals, which involves emotional, social, and exploratory responses of individuals and groups towards corpses. Stillborn babies and dead infants often elicit maternal and alloparental care that can persist for days, weeks, or even months, especially in primates. After this period, cannibalistic acts can occur not only by groupmates but also by the mother. Such cannibalism has been reported both in captive and wild primate groups, suggesting that the phenomenon is evolutionary adaptive. Here, we report a case in drills (Mandrillus leucophaeus), a largely unstudied monkey species. We collected data from the birth to the death of the infant on maternal and alloparental care towards the newborn across three phases: pre-mortem, post-mortem, and post-mortem cannibalism. The mother maintained high levels of grooming after the infant's death. Both the mother and other group members interacted with the dead baby by trying to engage its gaze. Two days after the death, the mother started to eat the corpse until it was almost completely consumed; there was no sharing with other group members. Although we cannot draw firm conclusions about potential benefits of the mother's behavior, this observation on drills adds a piece to the puzzle of thanatological behaviors and cannibalism in primates.

Adoption is an important form of allomaternal care in nonhuman primates, with implications for reproductive output and infant survival. Here, we report a kidnapping that became an adoption of a 3-week-old infant by a mother with her own infant in Tibetan macaques (Macaca thibetana). The adoptive mother nursed her "new" infant (allonursing), the first observation of this behavior in the species. The case provided a natural experiment for comparing how a female copes with a heavier burden of care for both her biological infant and another female's infant, compared to mothers caring for only one infant. Our results showed that the adoptive female spent more time foraging and resting, and less time in group social activity compared to females with a single infant. The adoptive female showed more instances of social bridging. Although the duration of post-bridging grooming received from group members decreased, the frequency of such grooming increased. We discuss this adoption with reference to possible factors involved in the evolution of adoption and allonursing behavior in Tibetan macaques.