Conservationists often advocate for landscape approaches to wildlife management while others argue for physical separation between protected species and human communities, but direct empirical comparisons of these alternatives are scarce. We relate African lion population densities and population trends to contrasting management practices across 42 sites in 11 countries. Lion populations in fenced reserves are significantly closer to their estimated carrying capacities than unfenced populations. Whereas fenced reserves can maintain lions at 80% of their potential densities on annual management budgets of $500 km(-2) , unfenced populations require budgets in excess of $2000 km(-2) to attain half their potential densities. Lions in fenced reserves are primarily limited by density dependence, but lions in unfenced reserves are highly sensitive to human population densities in surrounding communities, and unfenced populations are frequently subjected to density-independent factors. Nearly half the unfenced lion populations may decline to near extinction over the next 20-40 years.

Abstract:Elephant are believed to be one of the main ecological drivers in the conversion of savanna woodlands to grassland. We assessed the impacts of elephant on large trees (≥5 m in height) in the southern section of the Kruger National Park. Tree dimensions and utilization by elephant were recorded for 3082 individual trees across 22 transects (average length of 3 km and 10 m wide). Sixty per cent of the trees exhibited elephant utilization and 4% were dead as a direct result of elephant foraging behaviour. Each height class of tree was utilized in proportion to abundance. However, the size of the tree and the species influenced the intensity of utilization and foraging approach. Sclerocarya birrea was actively selected for and experienced the highest proportional utilization (75% of all trees). Interestingly, the proportion of large trees that were utilized and pushed over increased with distance from permanent water, a result which has implications for the provision of water in the KNP. We conclude that mortality is likely to be driven by a combination of factors including fire, drought and disease, rather than the actions of elephant alone. Further investigation is also required regarding the role of senescence and episodic mortality.

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Fencing conservation areas is ubiquitous in South Africa, however, the impact of these on predator ecology has not been tested. We used relationships between prey abundance and predator space use to create equations to predict the home range size of lions Panthera leo and leopards Panthera pardus. We then successfully tested these predictions using published data (Phinda, Makalali) and home range estimates from radio collared individuals reintroduced to Addo Elephant National Park. Spotted hyaena Crocuta crocuta ranges also seem food dependent. Lion home ranges in Addo (114 ± 5 km 2 ) required 180 fixes to be accurately estimated, spotted hyaena ranges (91 ± 10 km 2 ) required 200 fixes, and the solitary leopard had 295 fixes for a range of 38 km 2 . There were no sexual differences in home range sizes of lions or hyaenas. The daily food intake rate of lions, measured during continuous follows, was 9.8 kg per female equivalent unit. Dominant male lions (14.3 km for 8.3 kg) traveled furthest but obtained the least amount of food per day compared to subordinate males (8.9 km for 16.0 kg) and females (5.8 km for 17.9 kg). Subordinate males traveled the fastest and during the day, to avoid competition and harassment from the dominant males. From an evolutionary viewpoint, the use of fences for conservation has not affected the natural behaviour of the predators as they still conform to predictions derived from unfenced reserves; that is, prey abundance is the key factor in determining space use of large predators.

Abstract. The reintroduction of large predators provides a framework to investigate responses by prey species to predators. Considerable research has been directed at the impact that reintroduced wolves (Canis lupus) have on cervids, and to a lesser degree, bovids, in northern temperate regions. Generally, these impacts alter feeding, activity, and ranging behavior, or combinations of these. However, there are few studies on the response of African bovids to reintroduced predators, and thus, there is limited data to compare responses by tropical and temperate ungulates to predator reintroductions. Using the reintroduction of lion (Panthera leo) into the Addo Elephant National Park (AENP) Main Camp Section, South Africa, we show that Cape buffalo (Syncerus caffer) responses differ from northern temperate ungulates. Following lion reintroduction, buffalo herds amalgamated into larger, more defendable units; this corresponded with an increase in the survival of juvenile buffalo. Current habitat preference of buffalo breeding herds is for open habitats, especially during the night and morning, when lion are active. The increase in group size and habitat preference countered initial high levels of predation on juvenile buffalo, resulting in a return in the proportion of juveniles in breeding herds to pre-lion levels. Our results show that buffalo responses to reintroduced large predators in southern Africa differ to those of northern temperate bovids or cervids in the face of wolf predation. We predict that the nature of the prey response to predator reintroduction is likely to reflect the trade-off between the predator selection and hunting strategy of predators against the life history and foraging strategies of each prey species.

Life sciences study designAll studies must disclose on these points even when the disclosure is negative. Sample sizeNo sample-size calculation was performed. We used camera trap data from 32 different protected areas in which about half lions were present. This is far beyond the sample sizes used in any study so far on herbivore behavior in response to predation risk. To calculate activitity patterns for each herbivore species, we set the sample size threshold at 100 captures per species per survey to increase the robustness of our estimates. Decreasing this threshold did not qualitatively change our results.Data exclusions We set the sample size threshold at 100 captures per species per survey to increase the robustness of our estimates. Decreasing this threshold did not qualitatively change our results. Thus, species with less than 100 captures were excluded. ReplicationThe design included replication of predator presence and absence, with 16 areas (replications) of lion presence and 16 areas (replications) of lion absence.Randomization Allocation of predator or herbivore presence was not done randomly, but based on natural occurence of herbivores and reintroduction of lions in protected area across South Africa. Nevertheless, this comes very close to a "natural experiment" as lions used to be present in all 32 protected areas and there is no bias in environmental characteristics (temperature, rainfall) between areas with and without lions present. BlindingData collection was done via camera traps so this could be seen as "blind" data collection for the purpose of this study. Reporting for specific materials, systems and methodsWe require information from authors about some types of materials, experimental systems and methods used in many studies. Here, indicate whether each material, system or method listed is relevant to your study. If you are not sure if a list item applies to your research, read the appropriate section before selecting a response.

Competitively dominant carnivore species can limit the population sizes and alter the behavior of inferior competitors. Established mechanisms that enable carnivore coexistence include spatial and temporal avoidance of dominant predator species by subordinates, and dietary niche separation. However, spatial heterogeneity across landscapes could provide inferior competitors with refuges in the form of areas with lower competitor density and/or locations that provide concealment from competitors. Here, we combine temporally overlapping telemetry data from dominant lions (Panthera leo) and subordinate African wild dogs (Lycaon pictus) with high-resolution remote sensing in an integrated step selection analysis to investigate how fine-scaled landscape heterogeneity might facilitate carnivore coexistence in South Africa's Hluhluwe-iMfolozi Park, where both predators occur at exceptionally high densities. We ask whether the primary lion-avoidance strategy of wild dogs is spatial avoidance of lions or areas frequented by lions, or if wild dogs selectively use landscape features to avoid detection by lions. Within this framework, we also test whether wild dogs rely on proactive or reactive responses to lion risk. In contrast to previous studies finding strong spatial avoidance of lions by wild dogs, we found that the primary wild dog lion-avoidance strategy was to select landscape features that aid in avoidance of lion detection. This habitat selection was routinely used by wild dogs, and especially when in areas and during times of high lion-encounter risk, suggesting a proactive response to lion risk. Our findings suggest that spatial landscape heterogeneity could represent an alternative mechanism for carnivore coexistence, especially as evershrinking carnivore ranges force inferior competitors into increased contact with dominant species.

BackgroundAcquiring greater understanding of the factors causing changes in vegetation structure - particularly with the potential to cause regime shifts - is important in adaptively managed conservation areas. Large trees (≥5 m in height) play an important ecosystem function, and are associated with a stable ecological state in the African savanna. There is concern that large tree densities are declining in a number of protected areas, including the Kruger National Park, South Africa. In this paper the results of a field study designed to monitor change in a savanna system are presented and discussed.Methodology/Principal FindingsDeveloping the first phase of a monitoring protocol to measure the change in tree species composition, density and size distribution, whilst also identifying factors driving change. A central issue is the discrete spatial distribution of large trees in the landscape, making point sampling approaches relatively ineffective. Accordingly, fourteen 10 m wide transects were aligned perpendicular to large rivers (3.0–6.6 km in length) and eight transects were located at fixed-point photographic locations (1.0–1.6 km in length). Using accumulation curves, we established that the majority of tree species were sampled within 3 km. Furthermore, the key ecological drivers (e.g. fire, herbivory, drought and disease) which influence large tree use and impact were also recorded within 3 km.Conclusions/SignificanceThe technique presented provides an effective method for monitoring changes in large tree abundance, size distribution and use by the main ecological drivers across the savanna landscape. However, the monitoring of rare tree species would require individual marking approaches due to their low densities and specific habitat requirements. Repeat sampling intervals would vary depending on the factor of concern and proposed management mitigation. Once a monitoring protocol has been identified and evaluated, the next stage is to integrate that protocol into a decision-making system, which highlights potential leading indicators of change. Frequent monitoring would be required to establish the rate and direction of change. This approach may be useful in generating monitoring protocols for other dynamic systems.