American Journal of Primatology最新文献

Foraging is a fundamental aspect of the behavioural ecology of any species. Chimpanzees (Pan troglodytes) are generalist omnivores that inhabit a continuous range of forest environments. Accordingly, substantial differences in feeding ecology exist across chimpanzee sub-species and populations. Despite a persistent importance for the role of ripe fruit, chimpanzee diets typically include a large variety of food types. While considerable data exist on the foraging behaviour and diets of chimpanzees, these are typically limited to studies of single communities in distinct populations. Previous studies in the Budongo forest, Uganda, have focused on the Sonso community; less is known of the foraging behaviour of the neighbouring Waibira community. Here, we present detailed descriptive data on diet, activity, and food availability from this community. These were collected between October 2016 and June 2017 from focal observations of ten adult males and nine adult females, phenological monitoring of 168 chimpanzee food trees, and 4 ha of botanical plots. These chimpanzees generally conformed to the view of this species as a ripe fruit specialist, but were notably less frugivorous than other study communities and showed a considerable reliance on young leaves, in particular the leaves of Celtis mildbraedii, and on the seeds of Cynometra alexandrii during the dry season. Dietary diversity was similar to that of the neighbouring Sonso community, and our results support the idea that significant folivory is a general foraging strategy for Budongo Forest chimpanzees.

The evolution of human language remains a puzzle, with comparative approaches focusing on vocalizations, gestures, bimodal combinations, and, most recently, social interaction and turn-taking. The latter is characterized by cooperative, reciprocal exchanges of alternating short bursts of information among interactants. Some hallmarks of human conversational turn-taking have been found in other primate species, suggesting a possible specialization of great apes in gestural rather than vocal turn-taking. However, relatively little is known about the vocal turn-taking abilities of great apes. Here, we conducted a systematic, quantitative study on vocal exchanges of adult male chimpanzees (Pan troglodytes) living in a habituated community in the Loango National Park, Gabon. We focused on pant-hoots, the typical long-distance calls of chimpanzees, which have been argued to function in some contexts as question-and-answer-like exchanges, referred to as “inquiring pant-hoots” (IPHs), a term coined by Goodall (1986). We collected a comprehensive data set over a period of 16 months (January–May 2019; November 2019–November 2020) resulting in a total of 1747 pant-hoots of ten adult males. We analyzed the data with a special focus on general pant-hoot patterns, criteria for IPHs, social factors, and temporal organization. Overall, general calling frequency was highest in males with high social ranks, in larger parties, and during periods of increased fission and fusion. Twenty percent of calls qualified as IPHs and were positively correlated with smaller party size, higher fission–fusion rates, and the absence of close social partners. Temporal patterns were influenced by social bond strength, the presence of drumming, and an avoidance of overlap. Our findings add to the growing evidence of complex vocal turn-taking abilities in nonhuman primates, contradicting the notion of a specialization in gestural rather than vocal turn-taking for chimpanzees and possibly other great apes. They also emphasize the role of long-distance vocalizations for species in fission–fusion societies and visually dense environments.

Captive primates maintained at accredited institutions can live extraordinarily long lives and, as a result, are useful models for understanding the physiology of aging. Many institutions monitor primate health using serum chemistry panels and complete blood counts (CBCs), assays that capture organ and immune function and provide rich data for retrospective research. In this study, we compiled results from 169 serum chemistry panels and 168 CBCs collected between 2011 and 2022 at the Duke Lemur Center from 60 ring-tailed lemurs (Lemur catta), aged between 9 months and 32.8 years. Our dataset included 20 individuals who were 15 years or older, 10 of whom were 20 years or older. We found patterns consistent with gradual, age-related change in biomarkers associated with pancreas, kidney, and hepatobiliary function. Whereas concentrations of some markers increased with increasing age (e.g., amylase, lipase, gamma-glutamyl transferase, globulin, and total CO₂), concentrations of others decreased with increasing age (e.g., total bilirubin, calcium, and anion gap). We found significant age-by-sex interaction effects on blood urea nitrogen and cholesterol values, with females exhibiting sharper age-related increases in these analytes, particularly in late age, that could indicate steeper declines in kidney function than those experienced by males. Ultimately, our results capture a portrait of senescence in captive ring-tailed lemurs with extended longevity, with implications for the management of geriatric lemurs under human care. More broadly, including lemurs with diverse social systems and ecologies in retrospective studies of aging could illuminate physiological trends deeply rooted in the primate family tree and those uniquely shaped by evolution in Madagascar.

Traditional orangutan distribution and density monitoring requires costly line transect methods on the ground to detect their nests. Recently researchers have started to use unoccupied aerial vehicles, hereafter referred to as drones, to collect such data faster. However, manually inspecting the images acquired by the drone is time-consuming and hence costly. This study explored a deep learning method for the automated detection of orangutan nests in drone-captured aerial images, which can significantly improve the efficiency of orangutan monitoring efforts. The YOLO v10 model was trained using 868 images containing 1568 annotated orangutan nests collected from sites in Sabah, Malaysia, and Sumatra, Indonesia. Images were captured using multirotor and fixed-wing drones at varying altitudes. The model was trained using a transfer learning approach and achieved a mean Average Precision (mAP) of 0.831. The model was subsequently tested on two independent data sets with results showing a precision of 0.98 and recall of 0.88 for a multirotor drone and precision of 0.98 and a recall of 0.71 for a fixed-wing drone which has the benefit of being able to have longer duration flights. The high precision values indicate the model's accuracy in identifying true nest locations, while the recall values demonstrate its ability to detect a significant portion of the nests present in the images. The study highlights how using drones for data collection can reduce survey times compared to ground surveys, and the automation of nest detection further enhances the efficiency of drone surveys. However, the model's recall, especially for fixed-wing drone data, could be improved to ensure accurate population trend analyses. Further research should focus on expanding training data sets and refining models to account for different camera systems and environmental conditions.

We here present high-quality, population-level sequencing data from the X chromosome of the highly-endangered aye-aye, Daubentonia madagascariensis. Using both polymorphism- and divergence-based inference approaches, we quantify fine-scale mutation and recombination rate maps, study the demographic and selective processes additionally shaping variation on the X chromosome, and compare these estimates to those recently inferred from the autosomes in this species. Results suggest that an equal sex ratio is most consistent with observed patterns of variation, and that no sex-specific demographic patterns are needed to fit the empirical site frequency spectrum. Further, reduced rates of recombination were observed relative to the autosomes as would be expected, whereas mutation rates were inferred to be similar. Utilizing the estimated population history together with the mutation and recombination rate maps, we evaluated evidence for both recent and recurrent selective sweeps as well as balancing selection across the X chromosome, finding no significant evidence supporting the action of these episodic processes. Overall, these analyses provide new insights into the evolution of the X chromosome in this species, which represents one of the earliest splits in the primate clade.