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Hybridisation caused by anthropogenic movements of animals is a conservation concern. Black-faced impala (Aepyceros melampus petersi) are endemic to north-western Namibia and south-western Angola and are geographically isolated from common impala (A. m. melampus). Common impala have been translocated into the black-faced impala range creating a hybridisation risk. We validated 13 microsatellite markers for the detection of recent hybridisation events. We used these markers to assess the genetic variation and differentiation among impala within Etosha National Park (NP), Southern Cross Private Game Reserve (SCPGR), Namibia, and private game ranches across South Africa. We confirmed that “black-nosed” impala in South Africa were A. m. melampus, thus providing more evidence that the black blaze on the face cannot be used to distinguish between the two subspecies. We detected four hybrids and one common impala on SCPGR. These five individuals were removed from SCPGR at time of sampling. We found two potential hybrids in southern Etosha NP. Further sampling of animals within Etosha NP is recommended to determine the extent of hybridisation within the park. The Namibian Ministry of the Environment & Tourism is developing a management plan for black-faced impala across Namibia that includes genetic testing for hybrids.

Guided by the Optimum Foraging Theory,the Avoidance Concept, and assuming that the impala Aepyceros melampus melampus defecate purposevely at dung middens, we hypothesized that the impala's dung midden locations do not: (1) follow complete spatial randomness; (2) cluster along park tracks; and (3) cluster along the waterways. Using geolocation data for all impala dung middens in the Mukuvisi Woodland, Zmbabwe, the G(r) function revealed a clustered pattern at 0-100 m. Additionally, the 2 nd Order Gcross function showed evidence of spatial aggregation of dung middens to within 25 m of park tracks, but no evidence of spatial aggregation between impala dung middens and waterways. Our findings give insight into possible evolutionary decorum for optimum olfaction, energy-saving, disease,pest avoidance, and contamination avoidance.

Although the rumen microbiome of domesticated ruminants has been evaluated, few studies have explored the rumen microbiome of wild ruminants, and no studies have identified the rumen microbiome in the impala (Aepyceros melampus melampus). In the present study, next-generation sequencing and real-time polymerase chain reaction were used to investigate the diversity and density of the bacteria and methanogenic archaea residing in the rumen of five adult male impalas, culled during the winter dry season in Pongola, South Africa. A total of 15,323 bacterial 16S rRNA gene sequences (from five impala), representing 3,892 different phylotypes, were assigned to 1,902 operational taxonomic units (OTUs). A total of 20,124 methanogen 16S rRNA gene sequence reads (from four impala), of which 5,028 were unique, were assigned to 344 OTUs. From the total sequence reads, Bacteroidetes, Proteobacteria, and Firmicutes were the most abundant bacterial phyla. While the majority of the bacterial genera found were unclassified, Prevotella and Cupriavidus were the most abundant classified genera. For methanogens, the genera Methanobrevibacter and Methanosphaera represented 94.3 % and 4.0 % of the classified sequences, respectively. Most notable was the identification of Methanobrevibacter thaueri-like 16S rRNA gene sequence reads in all four impala samples, representing greater than 30 % of each individual’s total sequences. Both data sets are accessible through NCBI’s Sequence Read Archive (SRA), under study accession number SRP [048619]. The densities of bacteria (1.26×1010–3.82×1010 cells/ml whole rumen contents) and methanogens (4.48×108–7.2×109 cells/ml of whole rumen contents) from five individual impala were similar to those typically observed in domesticated ruminants.

Elephant and impala as intermediate feeders, having a mixed diet of grass and browse, respond to seasonal fluctuations of forage quality by changing their diet composition. We tested the hypotheses that (1) the decrease in forage quality is accompanied by a change in diet from more monocots in the wet season to more dicots in the dry season and that that change is more pronounced and faster in impala than in elephant; (2) mopane (Colophospermum mopane), the most abundant dicot species, is the most important species in the elephant diet in mopane woodland, whereas impala feed relatively less on mopane due to the high condensed tannin concentration; and (3) impala on nutrient-rich soils have a diet consisting of more grass and change later to diet of more browse than impala on nutrient-poor soils. The phosphorus content and in vitro digestibility of monocots decreased and the NDF content increased significantly towards the end of the wet season, whereas in dicots no significant trend could be detected. We argue that this decreasing monocot quality caused elephant and impala to consume more dicots in the dry season. Elephant changed their diet gradually over a 16-week period from 70% to 25% monocots, whereas impala changed diets rapidly (2–4 weeks) from 95% to 70% monocots. For both elephants and impala, there was a positive correlation between percentage of monocots and dicots in the diet and the in vitro digestibility of these forage items. Mopane was the most important dicot species in the elephant diet and its contribution to the diet increased significantly in the dry season, whereas impala selected other dicot species. On nutrient-rich gabbroic soils, impala ate significantly more monocots than impala from nutrient-poor granitic soils, which was related to the higher in vitro digestibility of the monocots on gabbroic soil. Digestibility of food items appears to be an important determinant of diet change from the wet to the dry season in impala and elephants.

The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator–prey pairs, lion–zebra and cheetah–impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator–prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate. Analysis and modelling of locomotor characteristics of two pursuit predator–prey pairs show that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival. Strength versus agility in the animal arms race Nature might be red in tooth and claw, but the race is not always won by the strong. A detailed study of how lions chase down zebras and cheetahs pursue impalas shows that, although the predators in each pair had substantially more muscle power than their prey, as well as much greater capacity to accelerate and decelerate, the prey species could slip away at lower speeds, at which they are more manoeuvrable. Nevertheless, predators need to be more athletic than their prey to sustain a viable kill rate.

Understanding how predation risk and plant defenses interactively shape plant distributions is a core challenge in ecology. By combining global positioning system telemetry of an abundant antelope (impala) and its main predators (leopards and wild dogs) with a series of manipulative field experiments, we showed that herbivores’ risk-avoidance behavior and plants’ antiherbivore defenses interact to determine tree distributions in an African savanna.Well-defended thorny Acacia trees (A. etbaica) were abundant in low-risk areas where impala aggregated but rare in high-risk areas that impala avoided. In contrast, poorly defended trees (A. brevispica) were more abundant in high- than in low-risk areas. Our results suggest that plants can persist in landscapes characterized by intense herbivory, either by defending themselves or by thriving in risky areas where carnivores hunt.

Unmanned Aerial Systems (UAS) are increasingly being used recreationally, commercially and for wildlife research, but very few studies have quantified terrestrial mammalian reactions to UAS approaches. We used two Vertical Take-off and Landing (VTOL) UAS to approach seven herbivore species in the Moremi Game Reserve, Botswana, after securing the relevant permissions. We recorded responses to 103 vertical and 120 horizontal approaches, the latter from three altitudes above ground level (AGL). We ran mixed logistic regressions to identify factors triggering (i) any response and (ii) an evasive response. We included effects of activity, altitude, direction of approach, distance, habitat, herd type, herd size, other species, target species, time, VTOL type and wind strength. Response triggers were linked to altitude, distance, habitat and target species. Elephant ( Loxodonta africana ), giraffe ( Giraffa camelopardalis ), wildebeest ( Connochaetes taurinus ) and zebra ( Equus quagga ) were most affected by VTOL approach, impala ( Aepyceros melampus ) and lechwe ( Kobus leche ) were least responsive, and tsessebe ( Damaliscus lunatus ) displayed intermediate sensitivity. VTOLs flown lower than 60 m AGL and closer than 100 m horizontal distance from target animals triggered behavioural responses in most species. Enforced regulations on recreational UAS use in wildlife areas are necessary to minimise disturbance to terrestrial mammals.

Impalas (Aepyceros melampus) are common African antelope. A retrospective study was conducted of 251 impala cases from game farms, national parks and zoos submitted by veterinarians and pathologists in South Africa (2003–2016). Histopathology slides as well as records of macroscopic lesions and additional diagnostic tests performed were examined. Non-infectious conditions, such as acute pulmonary congestion and oedema, cachexia, traumatic injury and anaesthetic-related mortality were the most common causes of morbidity and mortality. Bacterial sepsis was the most common infectious disease, whilst skeletal muscle and myocardial sarcocystosis and verminous cholangitis and pneumonia were the most common parasitic diseases. Although the retrospective nature of this study limits the significance of the relative prevalence of lesions in the three locations, management decisions and diagnostic plans may be informed by the results. Impala from game farms had significantly more cachexia cases than those from other locations. Impala from zoos had significantly more lymphoid depletion than those from other locations. These findings suggest that nutrition and pasture management, enclosure design, management of intra- and interspecies aggression and improved anaesthetic protocols could improve animal welfare and survival of impala on game farms and in zoos. This report presents a detailed survey of diseases and conditions found in impala that provides baseline data for veterinary pathologists.

Camera trap data are increasingly being used to characterise relationships between the spatiotemporal activity patterns of sympatric mammal species, often with a view to inferring inter-specific interactions. In this context, we attempted to characterise the kleptoparasitic and predatory tendencies of spotted hyaenas Crocuta crocuta and lions Panthera leo from photographic data collected across 54 camera trap stations and two dry seasons in Tanzania’s Ruaha National Park. We applied four different methods of quantifying spatiotemporal associations, including one strictly temporal approach (activity pattern overlap), one strictly spatial approach (co-occupancy modelling), and two spatiotemporal approaches (co-detection modelling and temporal spacing at shared camera trap sites). We expected a kleptoparasitic relationship between spotted hyaenas and lions to result in a positive spatiotemporal association, and further hypothesised that the association between lions and their favourite prey in Ruaha, the giraffe Giraffa camelopardalis and the zebra Equus quagga, would be stronger than those observed with non-preferred prey species (the impala Aepyceros melampus and the dikdik Madoqua kirkii). Only approaches incorporating both the temporal and spatial components of camera trap data resulted in significant associative patterns. The latter were particularly sensitive to the temporal resolution chosen to define species detections (i.e. occasion length), and only revealed a significant positive association between lion and spotted hyaena detections, as well as a tendency for both species to follow each other at camera trap sites, during the dry season of 2013, but not that of 2014. In both seasons, observed spatiotemporal associations between lions and each of the four herbivore species considered provided no convincing or consistent indications of any predatory preferences. Our study suggests that, when making inferences on inter-specific interactions from camera trap data, due regards should be given to the potential behavioural and methodological processes underlying observed spatiotemporal patterns.

Despite widespread acknowledgement that large mammal herbivory can strongly affect vegetation structure in savanna, we still lack a theoretical and practical understanding of savanna dynamics in response to herbivory. Like fire, browsing may impose height‐structured recruitment limitations on trees (i.e. a ‘browse trap’), but the demographics of herbivore effects have rarely been considered explicitly. Evidence that cohorts of trees in savannas may establish during herbivore population crashes and persist long term in savanna landscapes is anecdotal. Here, we use an experimental approach in Hluhluwe iMfolozi Park in South Africa, examining the response of grass biomass and tree populations to 10 years of graduated herbivore exclusion, and their subsequent response when exclosures were removed. We found that grazer exclusion increased grass biomass and that, despite presumable increases in fire intensity and grass competition, herbivore – especially mesoherbivore, including impala and nyala – exclusion resulted in increases in tree size. After herbivore reintroduction, grazers reduced grass biomass over short time‐scales, but tree release from browsing persisted, regardless of tree size. Synthesis. This work provides the first experimental evidence that release from browsing trumps grazer–grass–fire interactions to result in increases in tree size that persist even after browser reintroduction. Escape from the ‘browse trap’ may be incremental and not strictly episodic, but, over longer time‐scales, reductions in browsing pressure may lead to tree establishment events in savanna that persist even during periods of intense browsing. Explicitly considering the temporal demographic effects of browsing will be the key for a much‐needed evaluation of the potential global extent of herbivore impacts in savanna.