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.

Spatial co-occurrence patterns of sympatric large carnivores in a multi-use African system.

Interspecific interactions can be a key driver of habitat use, and must be accounted for in conservation planning. However, spatial partitioning between African carnivores, and how this varies with scale, remains poorly understood. Furthermore, most studies have taken place within small or highly protected areas, rather than in the heterogeneous, mixed-use landscapes characteristic of much of modern Africa. Here, we provide one of the first empirical investigations into population-level competitive interactions among an African large carnivore guild. We collected detection/non-detection data for an eastern African large carnivore guild in Tanzania's Ruaha-Rungwa conservation landscape, over an area of ~45,000 km2. We then applied conditional co-occupancy models to investigate co-occurrence between lion, leopard, and African wild dog, at two biologically meaningful scales. Co-occurrence patterns of cheetah and spotted hyaena could not be modelled. After accounting for habitat and detection effects, we found some evidence of wild dog avoidance of lion at the home range scale, and strong evidence of fine-scale avoidance. We found no evidence of interspecific exclusion of leopard by lion; rather, positive associations were observed at both scales, suggesting shared habitat preferences. We found little evidence of leopard habitat use being affected by wild dog. Our findings also reveal some interspecific effects on species detection, at both scales. In most cases, habitat use was driven more strongly by other habitat effects, such as biotic resources or anthropogenic pressures, than by interspecific pressures, even where evidence of the latter was present. Overall, our results help shed light on interspecific effects within an assemblage that has rarely been examined at this scale. We also demonstrate the effectiveness of sign-based co-occurrence modelling to describe interspecific spatial patterns of sympatric large carnivores across large scales. We conclude by discussing the implications of our findings for large carnivore conservation in modern African systems.

Trends and biases in African large carnivore population assessments: identifying priorities and opportunities from a systematic review of two decades of research.

African large carnivores have undergone significant range and population declines over recent decades. Although conservation planning and the management of threatened species requires accurate assessments of population status and monitoring of trends, there is evidence that biodiversity monitoring may not be evenly distributed or occurring where most needed. Here, we provide the first systematic review of African large carnivore population assessments published over the last two decades (2000-2020), to investigate trends in research effort and identify knowledge gaps. We used generalised linear models (GLMs) and generalised linear mixed models (GLMMs) to identify taxonomic and geographical biases, and investigated biases associated with land use type and author nationality. Research effort was significantly biased towards lion (Panthera leo) and against striped hyaena (Hyaena hyaena), despite the latter being the species with the widest continental range. African wild dog (Lycaon pictus) also exhibited a negative bias in research attention, although this was partly explained by its relatively restricted distribution. The number of country assessments for a species was significantly positively associated with its geographic range in that country. Population assessments were biased towards southern and eastern Africa, particularly South Africa and Kenya. Northern, western, and central Africa were generally under-represented. Most studies were carried out in photographic tourism protected areas under government management, while non-protected and trophy hunting areas received less attention. Outside South Africa, almost half of studies (41%) did not include authors from the study country, suggesting that significant opportunities exist for capacity building in range states. Overall, large parts of Africa remain under-represented in the literature, and opportunities exist for further research on most species and in most countries. We develop recommendations for actions aimed at overcoming the identified biases and provide researchers, practitioners, and policymakers with priorities to help inform future research and monitoring agendas.

Habitat use of and threats to African large carnivores in a mixed-use landscape.

Large carnivores increasingly inhabit human-affected landscapes, which exhibit heterogeneity in biotic resources, anthropogenic pressures, and management strategies. Understanding large carnivore habitat use in these systems is critical for their conservation, as is the evaluation of competing management approaches and the impacts of significant land-use changes. We used occupancy modeling to investigate habitat use of an intact eastern African large carnivore guild across the 45,000 km2 Ruaha-Rungwa landscape in south-central Tanzania. We determined the relative impact on five large carnivore species of biotic, anthropogenic, and management factors at the scales of home range selection and short-term use within home ranges. We also specifically tested the effect of abandonment of trophy hunting areas on large carnivore occurrence. Patterns of habitat use differed among species. Lions (Panthera leo) appeared affected by top-down limitation, as their occurrence was significantly negatively associated with illegal human activity (ß = -0.63 [SE 0.28]). African wild dogs (Lycaon pictus), instead, were limited by biotic features; the species was negatively associated with riverine areas of high sympatric predator density (ß = -1.00 [SE 0.43]) and used less-productive habitats. Spotted hyaena (Crocuta crocuta) and leopard (Panthera pardus) persisted in more disturbed areas and across habitat types. Large carnivore occurrence was not affected by whether an area was used for photographic or trophy hunting tourism; regular law enforcement was instead a better predictor of occurrence. All species fared better in actively managed hunting areas than those that had been abandoned by operators. Overall, our findings highlight the divergent habitat requirements within large carnivore guilds and the importance of adopting an integrated approach to large carnivore conservation planning in modern systems. We also identified a novel threat to African conservation areas in the form of decreased management investments associated with the abandonment of trophy hunting areas.

Uso de Hábitat y Amenazas para los Grandes Carnívoros de África en un Paisaje de Uso Mixto Resumen Cada vez más, los grandes carnívoros habitan paisajes afectados por los humanos, los cuales presentan heterogeneidad en los recursos bióticos, las presiones antropogénicas y las estrategias de manejo. El conocimiento sobre cómo usan el hábitat los grandes carnívoros en estos sistemas es crucial para su conservación, como lo es la evaluación de las estrategias competitivas de manejo y los impactos de los cambios significativos en el uso de suelo. Usamos modelos de ocupación para investigar el uso de hábitat por parte de un gremio intacto de grandes carnívoros en el este de África a lo largo de los 45,000 km2 del paisaje Ruaha-Rungwa en el centro-sur de Tanzania. Determinamos el impacto relativo que tienen los factores bióticos, antropogénicos y de manejo sobre cinco especies de grandes carnívoros a escala de selección de extensión doméstica y uso a corto plazo dentro de la extensión doméstica. También analizamos específicamente el efecto que tiene el abandono de las áreas de caza de trofeos sobre la presencia de los grandes carnívoros. Los patrones de uso de hábitat difirieron entre las especies. Los leones (Panthera leo) parecieron estar afectados por la limitación de arriba-abajo ya que su presencia estuvo asociada negativamente de manera importante con la actividad humana ilegal (ß = - 0.63 [SE 0.28]). El perro salvaje africano (Lycaon pictus) estuvo limitado por los elementos bióticos; la especie estuvo asociada negativamente con las áreas de alta densidad simpátrica de depredadores (ß = - 1.00 [SE 0.43]) y utilizó los hábitats menos productivos. La hiena moteada (Crocuta crocuta) y el leopardo (Panthera pardus) persistieron en áreas más perturbadas y en todos los tipos de hábitat. La presencia de los grandes carnívoros no se vio afectada si el área se usaba para caza de trofeos o turismo fotográfico; la aplicación regular de la ley fue un mejor pronóstico de la presencia. A todas las especies les fue mejor en las áreas de caza con gestión activa que en aquellas abandonadas por los operadores. En general, nuestros descubrimientos resaltan los distintos requerimientos de hábitat dentro de los gremios de grandes carnívoros y la importancia de adoptar un enfoque integrado para la planeación de la conservación de estas especies en los sistemas modernos. También identificamos una amenaza nueva para las áreas de conservación africana a manera de inversiones de manejo disminuidas asociadas con el abandono de las áreas de caza de trofeos.

Temporal partitioning and spatiotemporal avoidance among large carnivores in a human-impacted African landscape.

Africa is home to some of the world's most functionally diverse guilds of large carnivores. However, they are increasingly under threat from anthropogenic pressures that may exacerbate already intense intra-guild competition. Understanding the coexistence mechanisms employed by these species in human-impacted landscapes could help shed light on some of the more subtle ways in which humans may impact wildlife populations, and inform multi-species conservation planning. We used camera trap data from Tanzania's Ruaha-Rungwa landscape to explore temporal and spatiotemporal associations between members of an intact East African large carnivore guild, and determine how these varied across gradients of anthropogenic impact and protection. All large carnivores except African wild dog (Lycaon pictus) exhibited predominantly nocturnal road-travel behaviour. Leopard (Panthera pardus) appeared to employ minor temporal avoidance of lion (Panthera leo) in all sites except those where human impacts were highest, suggesting that leopard may have been freed up from avoidance of lion in areas where the dominant competitor was less abundant, or that the need for leopard to avoid humans outweighed the need to avoid sympatric competitors. Lion appeared to modify their activity patterns to avoid humans in the most impacted areas. We also found evidence of avoidance and attraction among large carnivores: lion and spotted hyaena (Crocuta crocuta) followed leopard; leopard avoided lion; spotted hyaena followed lion; and lion avoided spotted hyaena. Our findings suggest that large carnivores in Ruaha-Rungwa employ fine-scale partitioning mechanisms to facilitate coexistence with both sympatric species and humans, and that growing human pressures may interfere with these behaviours.

Density responses of lesser-studied carnivores to habitat and management strategies in southern Tanzania's Ruaha-Rungwa landscape.

Compared to emblematic large carnivores, most species of the order Carnivora receive little conservation attention despite increasing anthropogenic pressure and poor understanding of their status across much of their range. We employed systematic camera trapping and spatially explicit capture-recapture modelling to estimate variation in population density of serval, striped hyaena and aardwolf across the mixed-use Ruaha-Rungwa landscape in southern Tanzania. We selected three sites representative of different habitat types, management strategies, and levels of anthropogenic pressure: Ruaha National Park's core tourist area, dominated by Acacia-Commiphora bushlands and thickets; the Park's miombo woodland; and the neighbouring community-run MBOMIPA Wildlife Management Area, also covered in Acacia-Commiphora. The Park's miombo woodlands supported a higher serval density (5.56 [Standard Error = ±2.45] individuals per 100 km2) than either the core tourist area (3.45 [±1.04] individuals per 100 km2) or the Wildlife Management Area (2.08 [±0.74] individuals per 100 km2). Taken together, precipitation, the abundance of apex predators, and the level of anthropogenic pressure likely drive such variation. Striped hyaena were detected only in the Wildlife Management Area and at low density (1.36 [±0.50] individuals per 100 km2), potentially due to the location of the surveyed sites at the edge of the species' global range, high densities of sympatric competitors, and anthropogenic edge effects. Finally, aardwolf were captured in both the Park's core tourist area and the Wildlife Management Area, with a higher density in the Wildlife Management Area (13.25 [±2.48] versus 9.19 [±1.66] individuals per 100 km2), possibly as a result of lower intraguild predation and late fire outbreaks in the area surveyed. By shedding light on three understudied African carnivore species, this study highlights the importance of miombo woodland conservation and community-managed conservation, as well as the value of by-catch camera trap data to improve ecological knowledge of lesser-studied carnivores.

Spatial variation in leopard (Panthera pardus) site use across a gradient of anthropogenic pressure in Tanzania's Ruaha landscape.

Understanding large carnivore occurrence patterns in anthropogenic landscapes adjacent to protected areas is central to developing actions for species conservation in an increasingly human-dominated world. Among large carnivores, leopards (Panthera pardus) are the most widely distributed felid. Leopards occupying anthropogenic landscapes frequently come into conflict with humans, which often results in leopard mortality. Leopards' use of anthropogenic landscapes, and their frequent involvement with conflict, make them an insightful species for understanding the determinants of carnivore occurrence across human-dominated habitats. We evaluated the spatial variation in leopard site use across a multiple-use landscape in Tanzania's Ruaha landscape. Our study region encompassed i) Ruaha National Park, where human activities were restricted and sport hunting was prohibited; ii) the Pawaga-Idodi Wildlife Management Area, where wildlife sport hunting, wildlife poaching, and illegal pastoralism all occurred at relatively low levels; and iii) surrounding village lands where carnivores and other wildlife were frequently exposed to human-carnivore conflict related-killings and agricultural habitat conversion and development. We investigated leopard occurrence across the study region via an extensive camera trapping network. We estimated site use as a function of environmental (i.e. habitat and anthropogenic) variables using occupancy models within a Bayesian framework. We observed a steady decline in leopard site use with downgrading protected area status from the national park to the Wildlife Management Area and village lands. Our findings suggest that human-related activities such as increased livestock presence and proximity to human households exerted stronger influence than prey availability on leopard site use, and were the major limiting factors of leopard distribution across the gradient of human pressure, especially in the village lands outside Ruaha National Park. Overall, our study provides valuable information about the determinants of spatial distribution of leopards in human-dominated landscapes that can help inform conservation strategies in the borderlands adjacent to protected areas.

The diet of open-habitat chimpanzees (Pan troglodytes schweinfurthii) in the Issa valley, western Tanzania.

Comparative data on the diets of extant primates inform hypotheses about hominin resource use. Historically, data describing chimpanzee diets stem primarily from forest-dwelling communities, and we lack comparative data from chimpanzees that live in mosaic habitats that more closely resemble those reconstructed for Plio-Pleistocene hominins. We present data on the diet of a partially-habituated community of open habitat chimpanzees (Pan troglodytes schweinfurthii) from the Issa valley, western Tanzania, collected over a four-year period. Based mostly on macroscopic faecal analysis, Issa chimpanzees consumed a minimum of 69 plant species. There was no relationship between plant consumption and either fruit availability or feeding tree density; the most frequently consumed plant species were found in riverine forests, with woodland species consumed more frequently during the late dry season. We conclude by contextualising these findings with those of other open-habitat chimpanzee sites, and also by discussing how our results contribute towards reconstructions of early hominin exploitation of mosaic landscapes.