An ecological reassessment of the southern African carnivore guild: a case study from Member 4, Sterkfontein, South Africa

The southern African late Pliocene to early Pleistocene carnivore guild was much larger than that of the present day. Understanding how this guild may have functioned is important for the reconstruction of carnivore-hominin interactions and to assess the potential for hominin scavenging in southern Africa. In modern ecosystems, the coexistence of larger carnivore species is constrained by several factors, which include high levels of interspecific competition. Here, the composition of the fossil carnivore guild is examined using Sterkfontein Member 4 (Cradle of Humankind, South Africa) as a case study. Sterkfontein Member 4 contains 10 larger carnivore taxa (body mass > 21.5 kg) and may also contain two Australopithecus species. Two possible causes of higher numbers of carnivore species in the South African fossil record are initially considered. First, that there is a bias introduced through comparing assemblages of differing sizes; second, carnivore biodiversity may have been artificially inflated due to previous taxonomic splitting of carnivore species, such as Crocuta. These possibilities are rejected and modern ecological data are used to construct a simple spatial model to determine how many carnivores could have co-existed. Although the resulting model indicates that the carnivore taxa present in Member 4 could have co-occurred, modern ecological studies indicate that it is highly unlikely that they would have co-existed simultaneously. Considering the complex depositional processes that operate in the southern African cave sites, it is proposed that the larger carnivore guild observed in the Sterkfontein Member 4 fossil assemblage is a palimpsest created by time-averaging. In light of this, we suggest that sites which have a large number of carnivore taxa should be examined for time-averaging, while those sites which have relatively few species may be a better reflection of carnivore communities.     

Heterogeneity in the density of spotted hyaenas in Hluhluwe-iMfolozi Park,South Africa

Animal population sizes and trends, as well as their distributions, are essential information to the understanding and conservation of ecosystems. During this study in Hluhluwe-iMfolozi Park, South Africa, a spotted hyaena Crocuta crocuta Erxleben, 1777 (Hyaenidae) population was surveyed by attracting individuals with pre-recorded sounds. The hyaena population (excluding cubs) is substantially larger (321 individuals) than the previous estimate of 200 and this population is the second largest protected population in South Africa. Average hyaena density, at 0.357 individuals/km², was relatively high compared to other southern African conservation areas, and range from 0 to 1.25 individuals/km² across sampling stations. For short periods, spatial heterogeneity in density was marked at small and large spatial scales, but decreased when averaged over a longer period. This heterogeneity may be important in promoting the coexistence of other large and mobile carnivores in Hluhluwe-iMfolozi Park by creating potential dynamic competition refugia in space and time. Furthermore, heterogeneity of hyaena density at smaller scales should influence studies investigating the avoidance of hyaenas by competitively inferior carnivores.     

Key factors and related principles in the conservation of large African carnivores

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Impact of Livestock Husbandry on Small- and Medium-Sized Carnivores in Kalahari Savannah Rangelands

ABSTRACT We analyzed relative sensitivities of small- and medium-sized carnivores to livestock husbandry (stocking rates and predator control) in Kalahari, South Africa, rangelands at a regional scale. We monitored small carnivores using track counts on 22 Kalahari farms across a land-use gradient ranging from low to high stocking rates and also interviewed each farm manager to identify farmers' perception of small carnivores as potential predators for livestock. We recorded 12 species of small- and medium-sized carnivores across 22 Kalahari farms. Stocking rate was the most important driving variable for local carnivore abundance. Abundance of all species was lowest on farms where stocking rate was high. Most farm managers perceived medium-sized carnivores, in particular, African wildcat (Felis silvestris lybica), black-backed jackal (Canis mesomelas), and caracal (Caracal caracal), as potential predators of livestock. Multiple regression analysis shows that black-backed jackal, African wildcat, and caracal were negatively affected by predator control measures, whereas bat-eared fox (Otocyon megalotis), cape fox (Vulpes chama), and small-spotted genet (Genetta genetta) were positively affected. Our results show a need for expanding research and conservation activities toward small- and medium-sized carnivores in southern African savannah rangelands. We, therefore, suggest developing a monitoring program combining passive tracking with indigenous knowledge of local Khoisan Bushmen to monitor carnivore populations, and we recommend additional predator removal experiments that manipulate predator densities.     

Prey availability and intraguild competition regulate the spatiotemporal dynamics of a modified large carnivore guild

Effective conservation management requires an understanding of the spatiotemporal dynamics driving large carnivore density and resource partitioning. In African ecosystems, reduced prey populations and the loss of competing guild members, most notably lion (Panthera leo), are expected to increase the levels of competition between remaining carnivores. Consequently, intraguild relationships can be altered, potentially increasing the risk of further population decline. Kasungu National Park (KNP), Malawi, is an example of a conservation area that has experienced large‐scale reductions in both carnivore and prey populations, leaving a resident large carnivore guild consisting of only leopard (Panthera pardus) and spotted hyena (Crocuta crocuta). Here, we quantify the spatiotemporal dynamics of these two species and their degree of association, using a combination of co‐detection modeling, time‐to‐event analyses, and temporal activity patterns from camera trap data. The detection of leopard and spotted hyena was significantly associated with the detection of preferred prey and competing carnivores, increasing the likelihood of species interaction. Temporal analyses revealed sex‐specific differences in temporal activity, with female leopard activity patterns significantly different to those of spotted hyena and male conspecifics. Heightened risk of interaction with interspecific competitors and male conspecifics may have resulted in female leopards adopting temporal avoidance strategies to facilitate coexistence. Female leopard behavioral adaptations increased overall activity levels and diurnal activity rates, with potential consequences for overall fitness and exposure to sources of mortality. As both species are currently found at low densities in KNP, increased risk of competitive interactions, which infer a reduction in fitness, could have significant implications for large carnivore demographics. The protection of remaining prey populations is necessary to mitigate interspecific competition and avoid further alterations to the large carnivore guild.     

Anthropogenic influences on spotted hyaena diet in the Kruger National Park,South Africa

Rapid urban expansion has led to an increase in carnivores that live close to human dominated environments. Some carnivore species have successfully adapted to these novel conditions and taken advantage of opportunities associated with human habitation. Whilst many studies have compared carnivores living in protected areas to those in an urban setting, few have looked at the relationships between carnivores and human habitation within protected areas. In this study, we examined the effects of human habitation on the diet of spotted hyaenas (Crocuta crocuta) in the Kruger National Park (KNP), South Africa. Our results suggested a limited effect of anthropogenic resources on spotted hyaena diet in the KNP. We found neither temporal nor spatial variation in the amount of, nor types of, anthropogenic material in spotted hyaena scats, despite observations of more road side litter close to large anthropogenic sites. We therefore suggest that anthropogenic resources may not have been utilised completely according to abundance. We encourage further research evaluating potential secondary effects of human activity and infrastructure on spotted hyaena diet and also stable isotope approaches that may provide further insights into the importance of anthropogenic food for spotted hyaenas inside the KNP.     

Seasonal variation in prey preference,diet partitioning and niche breadth in a rich large carnivore guild

Large carnivore community structure is affected by direct and indirect interactions between intra-guild members. Co-existence between different species within a carnivore guild may occur through diet, habitat or temporal partitioning. Since carnivore species are highly dependent on availability and accessibility of prey, diet partitioning is potentially one of the most important mechanisms in allowing carnivores to co-exist. Intra-guild interactions may vary over time as carnivore prey preference and diet overlap can change due to seasonal changes in resource availability. We conducted scat analysis to compare the seasonal changes in prey preference, diet partitioning and niche breadth of four large carnivore species, namely leopard Panthera pardus, spotted hyena Crocuta crocuta, brown hyena Parahyaena brunnea and wild dog Lycaon pictus in central Tuli, Botswana. Large carnivores in central Tuli display a high dietary overlap, with spotted hyena and brown hyena displaying almost complete dietary overlap and the other carnivore species displaying slightly lower but still significant dietary overlap. Dietary niche breadth for both hyena species was high possibly due to their flexible foraging strategies, including scavenging, while leopard and wild dog showed a relatively low niche breadth, suggesting a more specialised diet. High dietary overlap in central Tuli is possibly explained by the high abundance of prey species in the area thereby reducing competition pressure between carnivore species. Our research highlights the need to assess the influence of diet partitioning in structuring large carnivore communities across multiple study sites, by demonstrating that in prey rich environments, the need for diet partitioning by carnivores to avoid competition may be limited.     

Conservation of biodiversity in Scandinavian boreal forests: large carnivores as flagships, umbrellas, indicators, or keystones?

Large carnivores are often used as focal species (indicators, umbrellas, flagships or keystones) in conservation strategies either aimed at conserving carnivores, the rest of the biodiversity that occupies their habitats, or both. We evaluate their suitability for these roles in the context of boreal forest biodiversity conservation in the muti-use landscapes of Scandinavia. The enormous conflicts, especially with livestock, that carnivores cause in these areas makes them very controversial flagships to the extent that it may affect rural people's attitudes to conservation in general. Because of the broad habitat tolerance of large carnivores and their prey, and the difficulties in surveying carnivore numbers, they are very insensitive and impractical indicators of forest biodiversity. This ability of large carnivores to thrive in industrial forests means that the many species that are sensitive to modern forestry will not fall under the umbrella of areas managed for large carnivores. If large carnivores have a keystone function with respect to affecting the density of their ungulate prey it is likely to lead to even further conflicts with hunters who gain economic benefit from harvesting wild ungulates. In other words, none of the classic `ecological' arguments are likely to help justify large carnivore conservation, and large carnivore conservation is unlikely to help conserve the rest of the boreal forest's biodiversity. Based on these arguments we recommend that (1) justification for large carnivore conservation focus on the real philosophical and value orientated reasons rather than ecological justifications, (2) that this conservation should be brought about in practice by dedicated management programs that specifically address the conflicts caused by large carnivores, and (3) that boreal forest biodiversity is best conserved by specific actions designed to establish reserves or change forestry practices.     

Temporal Change in Functional Richness and Evenness in the Eastern African Plio-Pleistocene Carnivoran Guild

We analyze functional richness and functional evenness of the carnivoran guild in eastern Africa from 3.5 Ma to 1.5 Ma, and compare them to the present day. The data consist of characters of the craniodental apparatus of 76 species of fossil and extant carnivorans, divided into four 0.5 Ma time slices from 3.5 to 1.5 Ma, together with the modern fauna. Focus is on large (>21.5 kg) carnivores. Results show that the large carnivore guild has lost nearly 99% of its functional richness since 3.5 Ma, in a process starting prior to 2 Ma. Measurement of functional evenness shows the modern large carnivore guild to be unique in being randomly distributed in morphospace while in all past time slices there is significant clustering of species. The results are analyzed in the light of known changes to climate and environment in eastern Africa. We conclude that climate change is unlikely to explain all of the changes found and suggest that the evolution of early hominins into carnivore niche space, especially the evolution of derived dietary strategies after 2 Ma, played a significant part in the reduction of carnivore functional richness.     

Brain expansion in early hominins predicts carnivore extinctions in East Africa

While the anthropogenic impact on ecosystems today is evident, it remains unclear if the detrimental effect of hominins on co‐occurring biodiversity is a recent phenomenon or has also been the pattern for earlier hominin species. We test this using the East African carnivore fossil record. We analyse the diversity of carnivores over the last four million years and investigate whether any decline is related to an increase in hominin cognitive capacity, vegetation changes or climatic changes. We find that extinction rates in large carnivores correlate with increased hominin brain size and with vegetation changes, but not with precipitation or temperature changes. While temporal analyses cannot distinguish between the effects of vegetation changes and hominins, we show through spatial analyses of contemporary carnivores in Africa that only hominin causation is plausible. Our results suggest that substantial anthropogenic influence on biodiversity started millions of years earlier than currently assumed.     

Anthropogenic disturbance induces opposing population trends in spotted hyenas and African lions

Large carnivore populations are declining worldwide due to direct and indirect conflicts with humans. Protected areas are critical for conserving large carnivores, but increasing human-wildlife conflict, tourism, and human population growth near these sanctuaries may have negative effects on the carnivores within sanctuary borders. Our goals were to investigate how anthropogenic disturbance along the edge of the Masai Mara National Reserve, Kenya, influences the demography and space-use of two large carnivore species that engage in intense interspecific competition. Here we document, in one disturbed region of the Reserve, a rapid increase in the population size of one large predator, the spotted hyena (Crocuta crocuta), but a striking concurrent decline in numbers of another, the African lion (Panthera leo). Anthropogenic disturbances negatively affected lion populations, and decreasing lion numbers appear to have a positive effect on hyena populations, indicated here by an increase in juvenile survivorship. We also saw an increase in the number of livestock consumed by hyenas. Our results suggest human population growth and indirect effects of human activity along Reserve boundaries may be effecting a trophic cascade inside the Reserve itself. These results indicate both top-down and bottom-up processes are causing a shift in the carnivore community, and a major disruption of guild structure, inside the boundaries of one of the most spectacular protected areas in Africa.     

Census and distribution of large carnivores in the Tsavo national parks,a critical east African wildlife corridor

Kenya's Tsavo National Parks are a critical conservation area and the only wilderness corridor through densely populated human-dominated landscapes stretching from the East African coast to Lake Victoria, separating extensive undeveloped grasslands south of the equator from the undeveloped semiarid bushlands to the north. At nearly 21,000 km², Tsavo is one of four lion strongholds in East Africa and part of Africa's most important populations of all other large African carnivores. To provide baseline data on the status of large carnivores, a track survey was undertaken in 2013. Lions and both hyaena species were widely distributed across both parks, while cheetahs and wild dogs were more patchily distributed. Spotted hyaenas were the most abundant, with an estimated population of 3,903 ± 514 (95% CI), followed by lion (706 ± 201), striped hyaena (679 ± 144), leopard (452 ± 98), cheetah (154 ± 74) and wild dog (111 ± 92). Tsavo's carnivores suffer from bushmeat poaching, illegal grazing and retaliatory killing, and increasing human numbers on its periphery. Given Tsavo's importance as a stronghold for lions and an ecological corridor, increased investment in effective protection is strongly recommended. Evaluating trends will require complementary techniques in light of intensive monitoring requirements.     

Evidence that vulture restaurants increase the local abundance of mammalian carnivores in South Africa

Vulture restaurants are used worldwide as a conservation tool to provide threatened vultures with a source of supplementary carrion free from anthropogenic contaminants such as poisons and veterinary drugs. While the impacts of supplementary feeding sites on ecosystem and scavenging community dynamics have been investigated in Europe, no information is currently available for southern Africa. This study presents evidence that providing supplementary carrion for vultures stimulated an increase in local abundance of two species of mammalian carnivores, the brown hyaena (Hyaena brunnea) and the black‐backed jackal (Canis mesomelas). These findings require that the wider impacts of providing supplementary carrion for conserving threatened species are fully investigated.     

Direct use values and passive use values: implications for conservation of large carnivores

We made a quantitative analysis of the responses of urban and rural residents in Sweden to arguments supporting and opposing conservation of large carnivores. The most important arguments in favour of conservation were: “I want them [the large carnivores] to exist in Sweden, even if I will never see any of them”, “Sweden should share the responsibility of conserving the large carnivores” and “We owe it [conservation of large carnivores] to future generations”. We found only small differences between rural and urban residents. For arguments opposing conservation, the difference between rural and urban areas was slightly greater. The most important arguments opposing conservation of large carnivores were: “They may have serious negative impact on livestock farming”, “They may have serious negative impact on reindeer husbandry” and “May inflict suffering on injured livestock”. We conclude that there seems to be less support for direct use values such as hunting, ecotourism or just experiencing large carnivores, this may imply that the minimum viable population size can be used as a long-term management goal for large carnivore populations, possibly with an exception for bears. We also conclude that a separate conservation or management plan is needed for each species, since the conflicts with human interests vary greatly between the different carnivore species.     

Spatial and temporal avoidance of risk within a large carnivore guild

Within a large carnivore guild, subordinate competitors (African wild dog, Lycaon pictus, and cheetah, Acinonyx jubatus) might reduce the limiting effects of dominant competitors (lion, Panthera leo, and spotted hyena, Crocuta crocuta) by avoiding them in space, in time, or through patterns of prey selection. Understanding how these competitors cope with one other can inform strategies for their conservation. We tested how mechanisms of niche partitioning promote coexistence by quantifying patterns of prey selection and the use of space and time by all members of the large carnivore guild within Liuwa Plain National Park in western Zambia. Lions and hyenas specialized on wildebeest, whereas wild dogs and cheetahs selected broader diets including smaller and less abundant prey. Spatially, cheetahs showed no detectable avoidance of areas heavily used by dominant competitors, but wild dogs avoided areas heavily used by lions. Temporally, the proportion of kills by lions and hyenas did not detectably differ across four time periods (day, crepuscular, early night, and late night), but wild dogs and especially cheetahs concentrated on time windows that avoided nighttime hunting by lions and hyenas. Our results provide new insight into the conditions under which partitioning may not allow for coexistence for one subordinate species, the African wild dog, while it does for cheetah. Because of differences in responses to dominant competitors, African wild dogs may be more prone to competitive exclusion (local extirpation), particularly in open, uniform ecosystems with simple (often wildebeest dominated) prey communities, where spatial avoidance is difficult.     

Relationship Between Small-game Hunting and Carnivore Diversity in Central Spain

Small-game hunting plays an important economic role in central Spain and some game species are key food resources for threatened predators. Small carnivores may reduce numbers of important game species. To alleviate predation pressure on game populations, management is often focused on predator control. Control methods can be non-selective, and so could potentially have a negative impact on non-target carnivore species, affecting carnivore guild composition and diversity. Using data on carnivore diversity in 70 quadrants (5 × 5 km) in a large area of central Spain with two main land uses (small-game hunting and a mixture of big-game hunting and forestry), we assessed how game management was related to carnivore diversity. Carnivore species richness was significantly lower in those areas managed for small-game hunting than in areas where other land uses predominated. The apparently least affected species by predator control was the red fox (Vulpes vulpes), the main target species of predator control. Results suggested that low carnivore species richness was linked to small-game hunting activities, which was probably associated with non-selective predator control practices. Therefore, in order to reconcile carnivore conservation and economic goals it is imperative to develop and to evaluate selective predator control techniques.     

Drivers of flea (Siphonaptera) community structure in sympatric wild carnivores in northwestern Mexico

Host identity, habitat type, season, and interspecific interactions were investigated as determinants of the community structure of fleas on wild carnivores in northwestern Mexico. A total of 540 fleas belonging to seven species was collected from 64 wild carnivores belonging to eight species. We found that the abundances of some flea species are explained by season and host identity. Pulex irritans and Echidnophaga gallinacea abundances were significantly higher in spring than in fall season. Flea communities on carnivore hosts revealed three clusters with a high degree of similarity within each group that was explained by the flea dominance of E. gallinacea, P. simulans, and P. irritans across host identity. Flea abundances did not differ statistically among habitat types. Finally, we found a negative correlation between the abundances of three flea species within wild carnivore hosts. Individual hosts with high loads of P. simulans males usually had significantly lower loads of P. irritans males or tend to have lower loads of E. gallinacea fleas and vice‐versa. Additionally, the logistic regression model showed that the presence of P. simulans males is more likely to occur in wild carnivore hosts in which P. irritans males are absent and vice‐versa. These results suggest that there is an apparent competitive exclusion among fleas on wild carnivores. The study of flea community structure on wild carnivores is important to identify the potential flea vectors for infectious diseases and provide information needed to design programs for human health and wildlife conservation.     

Inferring palaeoecology in extinct tremarctine bears (Carnivora,Ursidae) using geometric morphometrics

Figueirido, B. & Soibelzon, L.H. 2009: Inferring palaeoecology in extinct tremarctine bears (Carnivora, Ursidae) using geometric morphometrics. Lethaia, Vol. 43, pp. 209–222. In this study we explore the ecomorphological patterns of extinct tremarctine bears in South America during the Great American Biotic Interchange (GABI). These patterns are used to derive palaeoautoecological inferences in extinct tremarctines and their palaeosinecological relationships within Plio‐Pleistocene ecosystems. We used geometric morphometrics of landmark data to recover the shape of the craniomandibular skeleton of bears. The results reveal different ecomorphological specializations in extinct tremarctines during the Plio‐Pleistocene of South America. Indeed, these bears could have increased the percentage of plant matter in their diets according with the increased diversity of large carnivores in South America after the GABI. Omnivorous bears retain the ability to behave as carnivores or herbivores depending on resource availability. This fact strongly supports that bears are one of the most ecologically and morphologically adaptable members of the large carnivore guild. Moreover, their skull morphology could reflect ecological adaptations under different selection pressures with the required evolutionary time. □Evolution, GABI, geometric morphometrics, palaeoecology, Tremarctinae.     

Densities of spotted hyaena (Crocuta crocuta) and African golden wolf (Canis anthus) increase with increasing anthropogenic influence

We report densities of spotted hyaena (Crocuta crocuta) and African golden wolf (Canis anthus) in Enderta district in northern Ethiopia with high human and low natural prey densities. We estimated spotted hyaena and African golden wolf abundance and characterized their spatial distribution with three methods we surveyed four road-transects for 66 nights during dry (n = 41) and wet (n = 25) seasons, we used 34 calling stations and we mapped all active spotted hyaena dens at the time of the survey. The density of spotted hyaena and African golden wolf increased with proximity to towns where human density was higher. A total of 562 spotted hyaena and 63 African golden wolf responded to calling stations, leading to estimates of 1145 spotted hyaena and 166 African golden wolf in Enderta district. This method also found a significantly higher spotted hyaena and African golden wolf abundance in high human density areas. Maximum response radius was 2.8 km for spotted hyaena and 2.5 km for African golden wolf, and response probability was 0.83 for spotted hyaena and 0.8 for African golden wolf, respectively. We found 40 active spotted hyaena dens with 1507 remnants of prey, and the majority of the dens were located close to rivers and villages. Our findings show a positive relationship between spotted hyaena, African golden wolf and human concentrations that might demonstrate a case of exceptional coexistence of humans and carnivores, both at high densities. We suggest further investigations into co-adaptations between humans and predators in the study area.