Between forest and croplands: Nocturnal behavior in wild chimpanzees of Sebitoli, Kibale National Park, Uganda

Geographical Variation of Diet Composition of Cervus nippon kopschi in Jiangxi, China Based on DNA Metabarcoding

Food resources are the fundamental basis for the survival and reproduction of animals. Diet research is the foundation for understanding their ecological habits and is of great significance for evaluating their survival status and carrying out effective protection and management. South China sika deer (Cervus nippon kopschi) is the most endangered subspecies of wild sika deer in China, with a small population and a shrinking distribution area. Here, we used DNA metabarcoding technology to study the diet composition of C. n. kopschi in Taohongling Sika Deer National Nature Reserve in Jiangxi, China. Comparative analysis of diet composition among different areas (A-E) of C. n. kopschi was conducted, as well as C. n. hortulorum raised in the same areas. We found that the dominant families in the diet composition of C. n. kopschi were Rosaceae (46.73% of relative abundance), Anacardiaceae (6.02%), Poaceae (5.54%), and Fabaceae (3.92%), with Rubus (45.43%) being the absolute dominant genus. Thirty-two preferred plant species were identified in the diet of C. n. kopschi. The highest relative abundance (45%) was Rubus reflexus. The dominant family and genus in the diet composition of C. n. hortulorum were Fabaceae (33.89%) and Pueraria (32.87%), respectively. Of the 15 preferred plant species, the highest relative abundance was Pueraria montana (33%). The richness, diversity, and evenness of diet composition in Area B of C. n. kopschi were the highest among all areas, with significant differences compared to Areas C, D, and E. Diet composition of deer in Area A did not differ significantly from those in other areas. Principal coordinate analysis (PCoA) and nonmetric multidimensional scaling (NMDS) both indicated a significant separation in the diet composition of C. n. kopschi and C. n. hortulorum, while Area B showed significant separation from the other areas. This study elaborates on the diet composition information of C. n. kopschi and can provide a reference for the protection and improvement of the habitat of sika deer.

A review of great ape behavioural responses and their outcomes to anthropogenic landscapes

Industrial expansion has brought humans and wildlife into closer contact, and added novel, complex dimensions to human-wildlife relationships. The seven great apes (chimpanzee, Bornean orangutan, Sumatran orangutan, Tapanuli orangutan, Eastern gorilla, Western gorilla, bonobo), the closest extant relatives to humans, have experienced substantial population declines resulting from anthropogenic activities. The effect of human activity on great ape behavioural ecology is therefore an emerging field of inquiry in primatology which has historically been minimally considered. This review explores how wild great apes respond behaviourally to human activities and environmental changes, synthesizing current knowledge and addressing potential outcomes and risks. Using precise search criteria, we found 96 studies documenting changes in great ape behaviour in response to human activity, and despite their broad geographic distribution, we found common patterns and responses across species to increasing human influence. Literature documented shifts in existing behaviour (57), the generation of novel behaviours (53) or reported both (15). Forty-three studies (45%) included direct (23) or indirect (20) assessment of the consequences of these behaviours. Only one study modelled a widespread loss of existing behaviours. The majority of studies included chimpanzees (67), followed by orangutans (19) and gorillas (19), and only 2 included bonobos. We found that the most frequently documented drivers of behavioural responses to anthropogenic activity were wide-scale land-use conversions in ape habitats. In response, apes have adopted crop foraging, and altered nesting behaviour, range use, and social strategies. While these responses appear to allow survival in the immediate sense, they may expose individuals to more risks in the long term. Analysis revealed that under many contexts changing great ape behaviour is putting strain on the human-ape relationship, resulting in injury, harassment, and even the killing of apes. We found examples of tolerant relationships between humans and apes shifting towards conflict, potentially worsening the conservation crisis and inviting inquiry into tolerance thresholds among human communities. We emphasize the importance of community-engaged strategies for reducing competition over resources and conclude that great ape behavioural responses to human activity must be interpreted through a locally specific lens.

Ecological and Social Pressures Influence Diel Activity Patterns in Wild Tibetan Macaques

The nighttime behavior of diurnal species is a "black box." Although diurnal animals spend approximately half their lives in the dark, research has, for too long, relied on the simplifying assumption that what we can't observe isn't important. Advances in our ability to monitor nighttime behavior reveal that this is incorrect; essential biological and behavioral processes play out in the dark which are critical for understanding a species' ecology and evolution. We conducted our study from November 2021 to January 2022, using noninvasive 4G solar-powered night-vision cameras to quantitatively assess the impact of environmental and social factors on the diel activity patterns of wild Tibetan macaques at Mt. Huangshan, China. We find that Tibetan macaques maintain high levels of sleep throughout the night, as is typical for diurnal animals. However, non-sleep activity still accounted for 18.28% ± 0.45% of the total nighttime period, with activity occurring throughout the night. Notably, there was a peak in activity at midnight, including resting, movement, and social. Low temperatures significantly reduced daytime activity levels, while increasing nighttime activity, indicating that extreme temperatures have divergent impacts on activity levels during the day versus the night. Additionally, social activities were more frequent among females during the day, whereas males were more socially active at night. The distinct patterns of social activities during the day and night highlight the crucial role of social factors in nocturnal activities. The night-vision cameras have proven to be an effective research tool, allowing for a deeper understanding of primate behavior patterns and social structures. This provides new avenues for future research into the drivers of nighttime behavioral patterns across species.

Running the Risk: Road-Crossing Behavior in Wild Chimpanzees (Pan troglodytes) in an Anthropogenic Habitat in Uganda

Recent research highlights the behavioral flexibility of wild chimpanzees in response to human-induced changes in their environment, including agricultural and infrastructural development. The expansion of road networks threatens chimpanzee populations across Africa. Studying their road-crossing behavior, especially outside protected areas where road impacts are greatest, helps identify factors influencing their choices and flexibility. This study seeks to gain a deeper understanding of how chimpanzees navigate busy roads and assess the danger posed by roads. Such insights are needed to develop effective conservation strategies in regions facing escalating human impact, including recommendations for the design and management of traffic on existing and future roads. Using a dataset of 129 video-recorded road crossings spanning 38 months, we analyzed the behavioral adjustments of chimpanzees in Bulindi, Uganda, when crossing a recently paved, busy main road within their home range. Using generalized linear mixed models, we investigated chimpanzee risk perception, protective and cooperative behaviors, vigilance, and progression order during road crossings. We identified variations in their behavior according to age-sex of individuals, group composition, and level of risk. We found that Bulindi chimpanzees exhibit behavioral strategies to reduce risks of collision or close encounters with humans on the road, as previously described. However, they were less vigilant than expected. We suggest that the chimpanzees have developed tolerance of the risks presented by the road, owing to their long history of crossing it before it was tarmacked and widened, and their familiarity with local people and motor traffic. Our results provide further evidence of the flexibility of wild chimpanzees. However, road crossings remain highly risky for large mammals like great apes, necessitating measures to mitigate the impact of road development on this and other endangered species (e.g. speed bumps, police enforcement, public awareness raising).

Chimpanzee Activity and Behavioral Diversity Extends Across 24 Hours in Both Captive and Wild Settings

Studying nocturnal behavior is crucial for understanding the full scope of a species' behavioral flexibility so as to inform the conservation of wild populations and the care of captive individuals. However, this aspect of primate behavior is understudied, especially in great apes, which exhibit some of the widest documented behavioral diversity and flexibility. Our investigation is among the first to systematically compare the 24 h activity patterns and behavioral activities of captive chimpanzees (Saint Louis Zoo, USA) with those of wild chimpanzees (three sites across the Nouabalé-Ndoki National Park in the Republic of Congo) and a published data set of the nocturnal behavior of all chimpanzee subspecies. Furthermore, we examined the influence of human activity and changes to the group's composition on the activity patterns and nocturnal behaviors of the zoo-living chimpanzees. Our results reveal that the zoo-living chimpanzees exhibit significantly different activity patterns compared to their wild counterparts, with increased nocturnal activity (particularly in the early morning) and more observations of feeding and social behaviors at night. Additionally, the absence of human visitors and a change in the group's composition were found to influence these activity patterns. These findings underscore the importance of integrating more holistic approaches to captive primate care and wild primate conservation. This study also highlights the immense potential of implementing remote monitoring technology, such as video camera traps, across contexts. Such data that extend across contexts benefit not only the captive and wild great apes but also provide opportunities for caregivers, conservation managers, and students who are involved in these collaborative initiatives.

Changes in movement patterns in relation to sun conditions and spatial scales in wild western gorillas

For most primates living in tropical forests, food resources occur in patchworks of different habitats that vary seasonally in quality and quantity. Efficient navigation (i.e., spatial memory-based orientation) towards profitable food patches should enhance their foraging success. The mechanisms underpinning primate navigating ability remain nonetheless mostly unknown. Using GPS long-term tracking (596 days) of one group of wild western lowland gorillas (Gorilla gorilla gorilla), we investigated their ability to navigate at long distances, and tested for how the sun was used to navigate at any scale by improving landmark visibility and/or by acting as a compass. Long episodic movements ending at a distant swamp, a unique place in the home range where gorillas could find mineral-rich aquatic plants, were straighter and faster than their everyday foraging movements relying on spatial memory. This suggests intentional targeting of the swamp based on long-distance navigation skills, which can thus be efficient over a couple of kilometres. Interestingly, for both long-distance movements towards the swamp and everyday foraging movements, gorillas moved straighter under sunlight conditions even under a dense vegetation cover. By contrast, movement straightness was not markedly different when the sun elevation was low (the sun azimuth then being potentially usable as a compass) or high (so providing no directional information) and the sky was clear or overcast. This suggests that gorillas navigate their home range by relying on visual place recognition but do not use the sun azimuth as a compass. Like humans, who rely heavily on vision to navigate, gorillas should benefit from better lighting to help them identify landmarks as they move through shady forests. This study uncovers a neglected aspect of primate navigation. Spatial memory and vision might have played an important role in the evolutionary success of diurnal primate lineages.

Nocturnal selective pressures on the evolution of human musicality as a missing piece of the adaptationist puzzle

Human musicality exhibits the necessary hallmarks for biological adaptations. Evolutionary explanations focus on recurrent adaptive problems that human musicality possibly solved in ancestral environments, such as mate selection and competition, social bonding/cohesion and social grooming, perceptual and motor skill development, conflict reduction, safe time-passing, transgenerational communication, mood regulation and synchronization, and credible signaling of coalition and territorial/predator defense. Although not mutually exclusive, these different hypotheses are still not conceptually integrated nor clearly derived from independent principles. I propose The Nocturnal Evolution of Human Musicality and Performativity Theory in which the night-time is the missing piece of the adaptationist puzzle of human musicality and performing arts. The expansion of nocturnal activities throughout human evolution, which is tied to tree-to-ground sleep transition and habitual use of fire, might help (i) explain the evolution of musicality from independent principles, (ii) explain various seemingly unrelated music features and functions, and (iii) integrate many ancestral adaptive values proposed. The expansion into the nocturnal niche posed recurrent ancestral adaptive challenges/opportunities: lack of luminosity, regrouping to cook before sleep, imminent dangerousness, low temperatures, peak tiredness, and concealment of identity. These crucial night-time features might have selected evening-oriented individuals who were prone to acoustic communication, more alert and imaginative, gregarious, risk-taking and novelty-seeking, prone to anxiety modulation, hedonistic, promiscuous, and disinhibited. Those night-time selected dispositions may have converged and enhanced protomusicality into human musicality by facilitating it to assume many survival- and reproduction-enhancing roles (social cohesion and coordination, signaling of coalitions, territorial defense, antipredatorial defense, knowledge transference, safe passage of time, children lullabies, and sexual selection) that are correspondent to the co-occurring night-time adaptive challenges/opportunities. The nocturnal dynamic may help explain musical features (sound, loudness, repetitiveness, call and response, song, elaboration/virtuosity, and duetting/chorusing). Across vertebrates, acoustic communication mostly occurs in nocturnal species. The eveningness chronotype is common among musicians and composers. Adolescents, who are the most evening-oriented humans, enjoy more music. Contemporary tribal nocturnal activities around the campfire involve eating, singing/dancing, storytelling, and rituals. I discuss the nocturnal integration of musicality's many roles and conclude that musicality is probably a multifunctional mental adaptation that evolved along with the night-time adaptive landscape.

Interindividual differences in crop foraging behavior of chimpanzees (Pan troglodytes schweinfurthii) at a forest–agriculture interface

The expansion of agriculture in equatorial areas is fragmenting and reducing wildlife habitats. For primates, it also increases opportunities to consume crops as high-energy resources, exacerbates conflicts with farmers, and increases exposure to diseases and agrochemicals at the edge of protected areas. In species with sex differences in ranging behavior, individual exposure to such opportunities and threats may vary by sex. Chimpanzees show a great feeding flexibility and are territorial species with varied ranging patterns according to site, sex, or individuals. Within a community whose territory is crossed by a high-traffic road and partially bordered by maize gardens, we tested hypotheses of interindividual differences in access to crops based on age, sex, ranging behavior, and kinship. By analyzing the presence of Sebitoli chimpanzees (Pan troglodytes schweinfurthii, Kibale National Park, Uganda) on video clips from 16 camera traps, we estimated the individual dispersion range across the community’s territory and the crop foraging frequency along maize gardens over 16 months. While all age and sex classes were represented at the forest–garden interface, large intrasex differences were observed: some mature males and females were not observed to participate. The crop foraging frequency of adult females in maize gardens was significantly correlated with the location of their ranging areas. Related individuals revealed similar range patterns within the forest territory without sharing crop foraging habits. However, social learning and energy and risks–benefits trade-offs as potential drivers of crop consumption are not excluded.