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Many studies on the coexistence of wildlife with livestock have focused primarily on similarsized species. Furthermore, many of these studies have used dietary overlap as a measure of potential competition between interacting species and thus lack the important link between dietary overlap and any negative effects on a particular species–a prerequisite for competition. Consequently, the mechanisms that drive interspecific interactions between wildlife and cattle are frequently overlooked. To address this, we used an experimental setup where we leveraged different cattle stocking rates across two seasons to identify the drivers of interspecific interactions (i.e. competition and facilitation) between smaller-bodied oribi antelope and cattle. Using direct foraging observations, we assessed dietary overlap and grass regrowth, and also calculated oribi nutritional intake rates. Ultimately, we found that cattle compete with, and facilitate, smaller-bodied oribi antelope through bottom-up control. Specifically, cattle facilitated oribi during the wet season, irrespective of cattle stocking density, because cattle foraging produced high-quality grass regrowth. In contrast, during the dry season, cattle and oribi did not co-exist in the same areas (i.e. no direct dietary overlap). Despite this, we found that cattle foraging at high densities during the previous wet season reduced the dry season availability of oribi’s preferred grass species. To compensate, oribi expanded their dry season diet breadth and included less palatable grass species, ultimately reducing their nutritional intake rates. Thus, cattle competed with oribi through a delayed, across-season habitat modification. We show that differences in body size alone may not be able to offset competitive interactions between cattle and wildlife. Finally, understanding the mechanisms that drive facilitation and competition are key to promoting coexistence between cattle and wildlife.

The neighbourhood of plants in a patch can shape vulnerability of focal plants to herbivores, known as an associational effect. Associational effects of plant neighbourhoods are widely recognised. But whether a single neighbouring plant can exert an associational effect is unknown. Here, we tested if single neighbours indeed do influence the likelihood that a focal plant is visited and eaten by a mammalian herbivore. We then tested whether any refuge effect is strengthened by having more neighbours in direct proximity to a focal plant. We used native plant species and a browser/mixed feeder mammalian herbivore (swamp wallabies (Wallabia bicolor)) free-ranging in natural vegetation. We found that a single neighbouring plant did elicit associational effects. Specifically, plant pairs consisting of one high-quality seedling next to a single low-quality plant were visited and browsed by wallabies later and less than pairs of two high-quality seedlings. Having more neighbours did not strengthen these associational effects. Compared with no neighbours, one or five low-quality neighbours had the same effect in delaying time taken for wallabies to first visit a plot and browse on a high-quality focal seedling. While traditionally a ‘patch’ refers to a broad sphere-of-influence neighbouring plants have on a focal plant, our findings suggest the influence of plant neighbours can range from the nearest individual neighbour to the entire plant neighbourhood. Such fine-scale associational effects are fundamentally important for understanding intricate plant-herbivore interactions, and ecologically important by potentially having knock-on effects on plant survival, in turn influencing plant community structure.

Water is vital for mammals. Yet, as ephemeral sources can be difficult to find, it raises the question, how do mammals locate water? Elephants ( Loxodonta africana ) are water-dependent herbivores that possess exceptional olfactory capabilities, and it has been suggested that they may locate water via smell. However, there is no evidence to support this claim. To explore this, we performed two olfactory choice experiments with semi-tame elephants. In the first, we tested whether elephants could locate water using olfactory cues alone. For this, we used water from two natural dams and a drinking trough utilised by the elephants. Distilled water acted as a control. In the second, we explored whether elephants could detect three key volatile organic compounds (VOCs) commonly associated with water (geosmin, 2-methylisoborneol, and dimethyl sulphide). We found that the elephants could locate water olfactorily, but not the distilled water. Moreover, they were also able to detect the three VOCs associated with water. However, these VOCs were not in the odour profiles of the water sources in our experiments. This suggests that the elephants were either able to detect the unique odour profiles of the different water sources or used other VOCs that they associate with water. Ultimately, our findings indicate that elephants can locate water olfactorily at small spatial scales, but the extent to which they, and other mammals, can detect water over larger scales (e.g. km) remains unclear.

Finding food is one of the most important aspects of an animal’s life. Yet, locating it can be challenging as the availability and quality of food varies both spatially and temporarily. To overcome these challenges, mammalian herbivores may use spatial memory or senses such as smell and vision. Recent studies have found that African elephants ( Loxodonta africana ) use olfactory cues to locate food patches and to select plants to eat within these patches. However, the extent to which they may also use visual cues, such as those associated with leaf colour, a proxy for food quality, when making foraging decisions is unknown. To address this knowledge gap, we tested whether African elephants were able to discriminate differences in leaf colour (i.e., light green: high-quality new growth, dark green: lower quality old growth, brown: poor-quality senesced vegetation) over a range of distances (i.e., 3, 5, 10, 20, 40, 80 m). Testing four semi-tame elephants using visual-based choice experiments between different coloured canvases, we found that the elephants were able to discriminate colour differences at close range (i.e., ≤ 10 m), but not beyond. This suggests that when feeding within a patch, African elephants may utilise the visual cues associated with leaf colour to help locate high-quality food (e.g., individual trees, branches, and leaves) and thus increase their foraging efficiency. However, as they were unable to discriminate between the different colours over distances > 10 m, it is unlikely that they use colour when making long-range foraging decisions such as selecting feeding patches.

As herbivores forage, they move across a wide range of topographical features. Yet, they tend to avoid terrain such as steep slopes where energetic costs of movement are high and there is a greater risk of falls and tumbles. Recent studies suggest that African elephants (Loxodonta africana) avoid steep slopes (e.g., > 15°). However, in reserves with undulating topography, elephants may have to use steep slopes to obtain food, especially when availability is limited in more gradual areas. To explore this, we investigated slope use by elephants in the Ithala Game Reserve, South Africa, where the topography varies greatly and ranges between 400 to 1400 masl. Using 8.5 years of positional data, we examined how slope use varied between herd types (14 breeding herds and 13 males), habitat type and season (wet vs. dry). Elephants were found primarily on slopes < 30° (i.e., 95% of the locations), while 67% of the locations were on slopes < 15°, and 52% on slopes < 10°. Breeding herds used steeper slopes (mean = 12.6° ± 0.08 SE) than bulls (mean = 12.0° ± 0.8 SE). In addition, habitat influenced slope use, with the steepest slopes used in woodlands and the most gradual used in built-up areas and grasslands. However, these slope use differences were very small (i.e., 0.6° to 9.7°) and thus unlikely to be biologically meaningful. Rather, the ability to detect these slight differences was likely an artefact of our large sample size (N = 23,837 locations). Moreover, slope use did not vary between the wet and dry seasons. Nevertheless, 5% of all the elephant locations occurred on very steep slopes (i.e., > 30°) and 33% were on slopes > 15°, indicating that although they may prefer flat terrain, when required, elephants will mountaineer.

While feeding, mammalian browsers (primarily eat woody plants) encounter secondary metabolites such as tannins. Browsers may bind these tannins using salivary proteins, whereas mammalian grazers (primarily eat grasses that generally lack tannins) likely would not. Ruminant browsers rechew their food (ruminate) to increase the effectiveness of digestion, which may make them more effective at binding tannins than nonruminants. Few studies have included a sufficient number of species to consider possible scaling with body mass or phylogenetic effects on salivary proteins. Controlling for phylogeny, we ran inhibition radial diffusion assays of the saliva of 28 species of African herbivores that varied in size, feeding strategy, and digestive system. We could not detect the presence of salivary proline-rich proteins that bind tannins in any of these species. However, using the inhibition radial diffusion assay, we found considerable abilities to cope with tannins in all species, albeit to varying degrees. We found no differences between browsers and grazers in the effectiveness of their salivary proteins to bind to and precipitate tannins, nor between ruminants and nonruminants, or scaling with body mass. Three species bound all tannins, but their feeding niches included one browser (gray duiker), one mixed feeder (bush pig), and one grazer (red hartebeest). Five closely related species of small ruminant browsers were very effective in binding tannins. Megaherbivores, considered generalists on account of their large body size, were capable of binding tannins. However the grazing white rhinoceros was almost as effective at binding tannins as the megaherbivore browsers. We conclude, contrary to earlier predictions, that there were no differences in the relative salivary tannin-binding capability that was related to common ancestry (phylogeny) or to differences in body size.

Two key factors that influence the foraging behaviour of group-living herbivores are food availability and individual dominance status. Yet, how the combination of these factors influences the patch-joining decisions of individuals foraging within groups has scarcely been explored. To address this, we focused on the patch-joining decisions of group-living domestic goats (Capra hircus). When individuals were tested against the top four ranked goats of the herd, we found that at patches with low food availability they avoided these dominant patch-holders and only joined subordinates (i.e. costs outweighed benefits). However, as the amount of food increased, the avoidance of the top ranked individuals declined. Specifically, goats shifted and joined the patch of an individual one dominance rank higher than the previous dominant patch holder when the initial quantity of food in the new patch was twice that of the lower ranking individual's patch (i.e. benefits outweighed costs). In contrast, when individuals chose between patches held by dominant goats, other than the top four ranked goats, and subordinate individuals, we found that they equally joined the dominant and subordinate patch-holders. This joining was irrespective of the dominance gap, absolute rank of the dominant patch-holder, sex or food availability (i.e. benefits outweighed costs). Ultimately, our results highlight that herbivores weigh up the costs and benefits of both food availability and patch-holder dominance status when making patch-joining decisions. Furthermore, as the initial quantity of food increases, food availability becomes more important than dominance with regard to influencing patch-joining decisions.

Altered disturbance regimes, increasing atmospheric CO2, and other processes have increased woody cover and homogenized vegetation in savannas across the planet. African savannas with extensive versus minimal woody cover often have vastly different animal communities. However, we lack a clear mechanistic understanding of why animal communities are changing with vegetation structure. Our goal for this study was to understand how vegetation structure in an African savanna shaped the perceived predation risk of small mammals, hence affecting their activity. Using a reciprocal measure of standard giving-up-densities, amount of food eaten, we found sharp declines in rodents’ perceived predation risk and increased rodent activity underneath shrub cover. This response was consistent across species; however, species showed subtle differences in their responses to grassy vegetation. Our findings suggest that areas of minimal or extensive shrub cover (shrub encroachment) may be homogenizing rodents’ perceptions of predation risk and thus shaping their use of space.

Male vocalizations associated with courtship can play a key role in mate selection. They may help females obtain information about males’ quality and identity and/or may contain species-specific properties that help prevent interspecies breeding. Despite vocalizations being a prominent part of the courtship of white rhinos, the role that they play in white rhino breeding behaviour has not been extensively studied. Both southern (SWR) and critically endangered northern white rhino (NWR) males intensively vocalize during courtship with hic calls. We examined these calls and found that call properties differed between NWR and SWR males. In addition, we found that individual SWR males could be identified with a high degree of accuracy using their hic calls and that the signature information capacity in hic calls would allow females to individually recognize about 11 adult males living in or moving through their home-ranges, which may help with mate selection. Then, we conducted playback experiments with wild anoestrus SWR females. The females discriminated between the NWR and SWR hic calls and between the SWR hic and SWR pant calls. However, we only found differences in the latency of observed behaviours, not in their duration or in the intensity of females’ reaction. This might suggest that females which are not in oestrus are not highly responsive to a male’s motivation (i.e., seeking contact or mating), but are more interested in assessing his dominance status or familiarity. Ultimately, our results indicate that courtship hic calls encode information which might help females choose mating partners.

Mammals commonly communicate olfactorily via urine. However, the extent to which they communicate via dung, another waste product, is unknown. Behavioural studies suggest that mammals can obtain information from dung odours but are unclear about the information transmitted. Moreover, an understanding of the volatile organic compounds (VOCs) released from dung is limited. To address this, we analysed the odours emitted from the dung of free-ranging white rhinos, and found that 2,3-dimethylundecane signalled an individual's sex, heptanal discriminated age class, nonane defined male territorial status and 2,6-dimethylundecane indicated female oestrous state. To validate these findings, we artificially reproduced key elements of the territorial and oestrous odour profiles (i.e. profiles likely to elicit behavioural responses from receivers). We then exposed free-ranging territorial males to these odours. In response, males elicited behaviours associated with the specific odours (e.g. territorial male (potential threat): reduced latency in assuming vigilance; oestrous female (potential mate): increased investigation). These results indicate that the VOCs identified from the dung of free-ranging individuals do transmit key information. Moreover, as white rhinos of all ages and sexes defecate communally, middens probably act as information centres. Furthermore, as many other mammals defecate communally, olfactory communication via dung odours is likely a widespread phenomenon.