Leopard predation on gelada monkeys at Guassa, Ethiopia

Lethal combats in the forest among wild western gorillas

Lethal intergroup encounters occur in many species because of sexual selection. While documented in mountain gorillas, they are absent in western gorillas as, instead, it is predicted by their higher feeding (frugivory) and mate competition (single-vs. multi-male groups). We investigate whether the injuries on three dead silverbacks and one adult female from four groups of western gorillas in the Central African Republic, resulted from interactions with gorillas or leopards. We identified two distinct injury patterns caused by gorillas (isolated lacerations, round wounds) and leopards (punctures clustered on head/neck) by analyzing injuries caused by mountain gorillas and leopards to gorillas and non-gorilla species, respectively. The western gorilla injury pattern is similar to that of mountain gorillas suggesting that lethal encounters occur, albeit infrequently, as predicted by sexual selection in a one-male society. While sexual dimorphism and polygynous sociality favored the evolution of violent encounters, multiple males in groups may influence their frequency.

Potential changes in the extent of suitable habitats for geladas (Theropithecus gelada) in the Anthropocene

BACKGROUND

Climate change coupled with other anthropogenic pressures may affect the extent of suitable habitat for species and thus their distributions. This is particularly true for species occupying high-altitude habitats such as the gelada (Theropithecus gelada) of the Ethiopian highlands. To explore the impact of climate change on species distributions, Species Distribution Modelling (SDM) has been extensively used. Here we model the current and future extent of sutibale habitat for geladas. Our modelling was based on 285 presence locations of geladas, covering their complete current distribution. We used different techniques to generate pseudoabsence datasets, MaxEnt model complexities, and cut-off thresholds to map the potential distribution of gelada under current and future climates (2050 and 2070). We assembled maps from these techniques to produce a final composite map. We also evaluated the change in the topographic features of gelada over the past 200 years by comparing the topography in current and historical settings.

RESULTS

All model runs had high performances, AUC = 0.87-0.96. Under the current climate, the suitable habitat predicted with high certainty was 90,891 km2, but it decreased remarkably under future climates, -36% by 2050 and - 52% by 2070. However, since the habitats of geladas already extend to mountaintop grasslands, no remarkable range shifts across elevation gradients were predicted under future climates.

CONCLUSIONS

Our findings indicated that climate change most likely results in a loss of suitable habitat for geladas, particularly south of the Rift Valley. Currently geladas are confined to higher altitudes and steep slopes compared to historical sightings, probably qualifying geladas as refugee species. The difference in topography is potentially associated with anthropogenic pressures that drove niche truncation to higher altitudes, undermining the climatic and topographic niche our models predicted. We recommend protecting the current habitats of geladas even when they are forecasted to become climatically unsuitable in the future, in particular for the population south of the Rift Valley.

Leopard predation on wild Sichuan snub-nosed monkeys

Predation is widely recognized as a powerful selective pressure on primate behavior and ecology, although knowledge of predator-prey relationships remains limited partly due to the rarity of directly observed attacks on primates. Here, we describe four confirmed or suspected instances of leopard (Panthera pardus) predation on free-ranging Sichuan (golden) snub-nosed monkeys (Rhinopithecus roxellana), a highly endangered colobine species endemic to China. We recorded predation events and the reactions of monkey group members. We suggest that the evolution of a multilevel society may be an adaptive response by Sichuan snub-nosed monkeys to the risk from leopards as well as other potential predators, one that balances the pressures of predation and intra-species competition and conflict.

Population structure and distribution of geladas (Theropithicus gelada, Ruppell 1835) in Kotu forest, Northern Ethiopia

Endemic gelada populations outside protected areas are less investigated, and population census data are not available. As a result, a study was conducted to investigate the population size, structure, and distribution of geladas in Kotu forest and associated grasslands, in northern Ethiopia. The study area was stratified into five dominant habitat types namely, grassland, wooded grassland, plantation forest, natural forest, and bushland based on dominant vegetation type. Each habitat type was further divided into blocks, and a total counting technique was used to count the individuals of gelada. The total mean population size of gelada in Kotu forest was 229 ± 6.11. The mean ratio of male to female was 1:1.178. The gelada age composition comprised is as follows: 113 (49.34%) adults, 77 (33.62%) sub-adults, and 39 (17.03%) juveniles. The mean number of group one-male unit ranged from 1.5 ± 0.2 in the plantation forest to 4.5 ± 0.7 in the grassland habitat. On the other hand, all-male unit social system group was recorded only from grassland (1.5) and plantation forest (1) habitats. The average band size (number of individuals per band) was 45.0 ± 2.53. The largest number of geladas was recorded from grassland habitat 68 (29.87%), and the lowest was recorded from plantation forest habitat 34 (14.74%). Even though, the sex ratio was female biased, the proportion of juveniles to other age classes was very low compared with geladas in relatively well-protected areas, indicating negative consequences for the future viability of the gelada populations in the area. Geladas were widely distributed over open grassland habitat. Therefore, for sustainable conservation of the geladas in the area, there is a need for integrated management of the area with special attention on the conservation of the grassland habitat.

Quantifying the movement, behaviour and environmental context of group-living animals using drones and computer vision

Methods for collecting animal behaviour data in natural environments, such as direct observation and biologging, are typically limited in spatiotemporal resolution, the number of animals that can be observed and information about animals' social and physical environments. Video imagery can capture rich information about animals and their environments, but image-based approaches are often impractical due to the challenges of processing large and complex multi-image datasets and transforming resulting data, such as animals' locations, into geographical coordinates. We demonstrate a new system for studying behaviour in the wild that uses drone-recorded videos and computer vision approaches to automatically track the location and body posture of free-roaming animals in georeferenced coordinates with high spatiotemporal resolution embedded in contemporaneous 3D landscape models of the surrounding area. We provide two worked examples in which we apply this approach to videos of gelada monkeys and multiple species of group-living African ungulates. We demonstrate how to track multiple animals simultaneously, classify individuals by species and age-sex class, estimate individuals' body postures (poses) and extract environmental features, including topography of the landscape and animal trails. By quantifying animal movement and posture while reconstructing a detailed 3D model of the landscape, our approach opens the door to studying the sensory ecology and decision-making of animals within their natural physical and social environments.

Ecological and social pressures interfere with homeostatic sleep regulation in the wild

Sleep is fundamental to the health and fitness of all animals. The physiological importance of sleep is underscored by the central role of homeostasis in determining sleep investment – following periods of sleep deprivation, individuals experience longer and more intense sleep bouts. Yet, most sleep research has been conducted in highly controlled settings, removed from evolutionarily relevant contexts that may hinder the maintenance of sleep homeostasis. Using triaxial accelerometry and GPS to track the sleep patterns of a group of wild baboons (Papio anubis), we found that ecological and social pressures indeed interfere with homeostatic sleep regulation. Baboons sacrificed time spent sleeping when in less familiar locations and when sleeping in proximity to more group-mates, regardless of how long they had slept the prior night or how much they had physically exerted themselves the preceding day. Further, they did not appear to compensate for lost sleep via more intense sleep bouts. We found that the collective dynamics characteristic of social animal groups persist into the sleep period, as baboons exhibited synchronized patterns of waking throughout the night, particularly with nearby group-mates. Thus, for animals whose fitness depends critically on avoiding predation and developing social relationships, maintaining sleep homeostasis may be only secondary to remaining vigilant when sleeping in risky habitats and interacting with group-mates during the night. Our results highlight the importance of studying sleep in ecologically relevant contexts, where the adaptive function of sleep patterns directly reflects the complex trade-offs that have guided its evolution.

Anthropogenic land-use and environmental factors affecting the species richness and occurrence of carnivores in the Faragosa-Fura Landscape of Southern Rift Valley, Ethiopia

Anthropogenic land-use changes pose significant threats to the diversity and occurrence of wildlife species around the world. We investigated how land-use and environmental factors affect the richness and occurrence of carnivore species in the Faragosa-Fura Landscape of the Southern Rift Valley of Ethiopia. We used the line transect method to collect data, combining three complementary field survey techniques: sign survey, camera trapping, and opportunistic sighting surveys. We confirmed the presence of 12 carnivore species belonging to six families, including the vulnerable Felidae species Panthera pardus. More species were found in the family’s Felidae and Herpestidae, while Hyaenidae and Mustelidae were composed of a single species each. The two large-sized species identified were Panthera pardus and Crocuta crocuta. The species richness was the highest in wetlands, while it was the lowest in the settlement. The occurrence of most carnivores was negatively associated with agricultural land and settlements, while they were positively associated with wetlands and altitude. Genetta genetta had the highest occurrence, while Panthera pardus had the lowest in the area. We concluded that of the studied habitats, wetlands are the most important, and anthropogenic land-uses have a negative impact on species richness. Our findings provide valuable baseline data for stakeholders making critical conservation decisions as well as researchers conducting related ecological studies in a human-dominated landscape. Based on our findings, we propose a basic approach for integrating land management and wildlife conservation.

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