Neopterin Levels in Bonobos Vary Seasonally and Reflect Symptomatic Respiratory Infections.

As environmental changes exacerbate the threat coming from infectious diseases in wild mammal species, monitoring their health and gaining a better understanding of the immune functioning at the species level have become critically important. Neopterin is a biomarker of cell-mediated immune responses to intracellular infections. We investigated the variation of urinary neopterin (uNeo) levels of wild, habituated bonobos (Pan paniscus) in relation to individual and environmental factors. We used 309 urine samples collected between 2010 and 2018 at the LuiKotale field site, DRC. Based on current knowledge on zoo-housed conspecifics and closely related species, we predicted uNeo levels to increase (1) during infections, (2) with increasing age, (3) over the gestation period and in estrous females; and (4) to vary seasonally. Our results showed uNeo levels varied over a one-year period and increased in individuals showing respiratory symptoms. Contrary to chimpanzees, uNeo levels did not vary with age or female reproductive status, possibly due to our small sample size. Our study provides a baseline for a better understanding of bonobo's immunocompetence in the context of socio-ecological pressures and for monitoring the health of wild populations.

What fecal analyses reveal about Manniophyton fulvum consumption in LuiKotale bonobos (Pan paniscus): A medicinal plant revisited.

Observations of animals in the wild can result in the discovery of plants for human medicinal purposes. In this context, our closest relatives, the great apes, are of particular interest. The Euphorbiaceae Manniophyton fulvum possesses both phytochemical and biomechanical properties. Its use in the genus Pan (P. troglodytes; P. paniscus) is thought to be based on its mechanical properties promoting the egestion of intestinal parasites, but additional observations from different habitats where the behavior is performed may shed more light on its true purpose. To improve our understanding of what triggers this behavior, we investigated M. fulvum consumption in wild bonobos at LuiKotale, Democratic Republic of the Congo between December 2018 and July 2020. Specifically, we tested the hypothesis that M. fulvum ingestion is related to gastro-intestinal parasite expulsion. Of 649 focal follows of 37 individuals from two habituated communities, consumption of M. fulvum was observed on 111 days (N = 507), independent of seasons, environmental factors and the plant's availability. A total of 588 fecal samples were assessed for the presence/absence of gastro-intestinal parasites. We found strongyle eggs in 2.89% of samples and their presence was not associated with the ingestion of M. fulvum or environmental conditions. We discuss the importance of seasonality in the life cycle of strongyle species that may influence the pattern of M. fulvum consumption observed at LuiKotale. Our data open additional perspectives concerning behavioral parameters such as the existence of a cultural component when comparing ingestion behavior between communities.

First report of a leopard (Panthera pardus)-bonobo (Pan paniscus) encounter at the LuiKotale study site, Democratic Republic of the Congo.

Predation is a major cause of mortality in non-human primates, and considered a selective force in the evolution of primate societies. Although larger body size is considered as protection against predation, evidence for predation on great apes by carnivores comes from chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), and orangutans (Pongo spp.). Here, we describe the first encounter between wild bonobos (Pan paniscus) and a leopard (Panthera pardus). A single leopard was confronted by a group of habituated bonobos for three hours. Two adult males and one adolescent female bonobo actively harassed the leopard, which remained still for most of the encounter and reacted only to close approaches by bonobos. While no predation was observed, their behaviours confirm that bonobos perceive leopards as potential predators. Our report adds novel information to descriptions from other African ape species, and sheds light on the behavioural repertoire of bonobos' anti-predation strategies. For future investigations, we suggest tagging leopards to remotely monitor their movements and allow assessment of encounter rates as one of several factors influencing predation pressure.