Marietjie Landman

Profiles, views and observations of visitors to the Addo Elephant National Park, Eastern Cape, South Africa

The views of visitors to national parks provide an important source of information to guide park planners and managers. A visitor questionnaire study was conducted in 2004 and 2005 in the Addo Elephant National Park, South Africa. A profile of the respondents, as well as records of their views on a number of park-related conservation and management issues, and of their observations of large and charismatic species (the ‘Big Five’) was compiled. The study clearly showed that national parks are important destinations for an African wildlife experience, along with other natural attractions that they have to offer. It also highlighted the scope for further visitor education, specifically aimed at improving the quality of their visits to the park. The relationship between elephant (Loxodonta africana) density and level of viewing success by visitors requires further investigation. Since the reintroduction of large predators, especially lion (Panthera leo), in the early 2000s, the daytime sighting rate of buffalo (Syncerus caffer) by visitors has increased markedly. Ongoing surveys, to monitor and expand on some of the aspects addressed in this study, are considered necessary in order to assist park staff to achieve conservation and management goals.

Understanding Long-Term Variations in an Elephant Piosphere Effect to Manage Impacts

Surface water availability is a key driver of elephant impacts on biological diversity. Thus, understanding the spatio-temporal variations of these impacts in relation to water is critical to their management. However, elephant piosphere effects (i.e. the radial pattern of attenuating impact) are poorly described, with few long-term quantitative studies. Our understanding is further confounded by the complexity of systems with elephant (i.e. fenced, multiple water points, seasonal water availability, varying population densities) that likely limit the use of conceptual models to predict these impacts. Using 31 years of data on shrub structure in the succulent thickets of the Addo Elephant National Park, South Africa, we tested elephant effects at a single water point. Shrub structure showed a clear sigmoid response with distance from water, declining at both the upper and lower limits of sampling. Adjacent to water, this decline caused a roughly 300-m radial expansion of the grass-dominated habitats that replace shrub communities. Despite the clear relationship between shrub structure and ecological functioning in thicket, the extent of elephant effects varied between these features with distance from water. Moreover, these patterns co-varied with other confounding variables (e.g. the location of neighboring water points), which limits our ability to predict such effects in the absence of long-term data. We predict that elephant have the ability to cause severe transformation in succulent thicket habitats with abundant water supply and elevated elephant numbers. However, these piosphere effects are complex, suggesting that a more integrated understanding of elephant impacts on ecological heterogeneity may be required before water availability is used as a tool to manage impacts. We caution against the establishment of water points in novel succulent thicket habitats, and advocate a significant reduction in water provisioning at our study site, albeit with greater impacts at each water point.

Shift in Black Rhinoceros Diet in the Presence of Elephant: Evidence for Competition?

In African large herbivore assemblages, megaherbivores dominate the biomass and utilise the greatest share of available resources. Consequently, they are considered a separate trophic guild that structures the food niches of coexisting large herbivores. However, there exists little empirical evidence on how food resources are shared within this guild, and none for direct competition for food between megaherbivores. Using the histological analysis of faeces, we explore this phenomenon for African elephant Loxodonta africana and black rhinoceros Diceros bicornis in the Addo Elephant National Park, South Africa, where the accumulated impacts of elephant have reduced browse availability. Despite being unable to generalise beyond our study sites, our observations support the predictions of competition theory (as opposed to optimality theory) by showing (1) a clear seasonal separation in resource use between these megaherbivores that increased as resource availability declined, and (2) rhinoceros changed their selectivity in the absence of elephant (using an adjacent site) by expanding and shifting their diet along the grass-browse continuum, and in relation to availability. Although black rhinoceros are generally considered strict browsers, the most significant shift in diet occurred as rhinoceros increased their preferences for grasses in the presence of elephant. We speculate that the lack of specialised grazing adaptations may increase foraging costs in rhinoceros, through reduced harvest- and handling-efficiencies of grasses. In the short-term, this may be off-set by an enhanced tolerance for low quality food and by seasonally mobilising fat reserves; however, the long-term fitness consequences require further study. Our data suggest that managing elephant at high densities may compromise the foraging opportunities of coexisting browsers. This may be particularly important in small, fenced areas and overlapping preferred habitats where impacts intensify.

Filling the gaps on the maps: historical distribution patterns of some larger mammals in part of southern Africa

Distribution data form the basis of the study of zoo-geography, which has applications in, inter alia, ecology and conservation. Written records were used to estimate the distribution patterns of some of the medium- to large-sized terrestrial mammals in central, southern and western South Africa, and neighbouring Lesotho, during the early historical period (late 1400 s to the 1920s). The sources of these records comprise mainly published or unpublished letters, journals, diaries or books written by literate pioneers – notably various missionaries, explorers, travellers, naturalists, military personnel, big game hunters and agro-pastoralists. The classification (according to record type) of the written records in key publications was standardised, and records overlooked by them are taken into account. Interpretation of the spatial patterns provided by the written records was aided by reference to supporting information, in the form of qualifying palaeontological, zoo-archaeological and museum records. Written records of acceptable quality are shown, together with supporting records (where applicable), on a series of species occurrence maps, which also depict the biomes that are represented in the study area. The information on these maps is interpreted, together with relevant information in the source texts and a map of the bioregions that constitute the biomes in question, to estimate distribution patterns that prevailed during the period under study. Data are presented for 27 genera, 36 species and 2 subspecies, comprising 7 carnivores and 30 herbivores. Despite the limitations associated with the use of written records, the information provided is considered to offer a realistic distribution pattern for most of the taxa covered. The use of supporting records is justified, since the majority of these corroborate the ranges derived from the written records. The present study enhances our knowledge of distribution patterns for these larger mammal species in a large part of the southern African sub-region during the early historical period. It also provides a first attempt to describe the sub-regional scale, historical, distribution patterns within the context of the broad biogeographical characteristics of the area in question. There is a need to extend the coverage achieved by this study to include the remaining approx. 30% of “South Africa”, i.e. the region incorporating South Africa, Lesotho and Swaziland, and also the area incorporated by the countries of Namibia, Botswana, Zimbabwe and Mozambique. This level of coverage will permit enhanced definition of historical distribution patterns for some larger mammals in the southern African sub-region. There is also a need to better understand the drivers, as well as the implications, of the observed changes in the distribution of the larger mammals since the start of the historical period.

Long-term monitoring reveals differing impacts of elephants on elements of a canopy shrub community

The conservation management of southern Africas elephants focuses on identifying and mitigating the extent and intensity of impacts on biological diversity. However, variation in the intensity of elephant effects between elements of biodiversity is seldom explored, which limits our ability to interpret the scale of the impacts. Our study quantifies >50 years of impacts in the succulent thickets of the Addo Elephant National Park, South Africa, contrasting hypotheses for the resilience of the canopy shrubs (a key functional guild) to elephants with those that argue the opposite. We also assess the impacts between elements of the community, ranging from community composition and structure to the structure of individual canopy species. We show the vulnerability of the canopy shrubs to transformation as the accumulated influences of elephants alter community composition and structure. The pattern of transformation is similar to that caused by domestic herbivores, which leads us to predict that elephants will eventually bring about landscape-level degradation and a significant loss of biodiversity. While we expected the canopy species to show similar declining trends in structure, providing insight into the response of the community as a whole, we demonstrate an uneven distribution of impacts between constituent elements; most of the canopy dominants exhibited little change, resisting removal. This implies that these canopy dominants might not be useful indicators of community change in thickets, a pattern that is likely repeated among the canopy trees of savanna systems. Our findings suggest that predicting elephant impacts, and finding solutions to the so-called “elephant problem,” require a broader and more integrated understanding of the mechanisms driving the changes between elements of biodiversity at various spatial and temporal scales.

Trophic rewilding as a climate change mitigation strategy

The loss of megafauna at the terminal Pleistocene has been linked to a wide range of Earth-system-level changes, such as altered greenhouse gas budgets, fire regimes and biome-level vegetation changes. Given these influences and feedbacks, might part of the solution for mitigating anthropogenic climate change lie in the restoration of extant megafauna to ecosystems? Here, we explore the potential role of trophic rewilding on Earths climate system. We first provide a novel synthesis of the various ways that megafauna interact with the major drivers of anthropogenic climate change, including greenhouse gas storage and emission, aerosols and albedo. We then explore the role of rewilding as a mitigation tool at two scales: (i) current and near-future opportunities for national or regional climate change mitigation portfolios, and (ii) more radical opportunities at the global scale. Finally, we identify major knowledge gaps that complicate the complete characterization of rewilding as a climate change mitigation strategy. Our perspective is urgent since we are losing the Earths last remaining megafauna, and with it a potential option to address climate change. This article is part of the theme issue ‘Trophic rewilding: consequences for ecosystems under global change’.

Diet shifts by adult flightless dung beetles Circellium bacchus, revealed using DNA metabarcoding, reflect complex life histories

Life history changes may change resource use. Such shifts are not well understood in the dung beetles, despite recognised differences in larval and adult feeding ability. We use the flightless dung beetle Circellium bacchus to explore such shifts, identifying dung sources of adults using DNA metabarcoding, and comparing these with published accounts of larval dung sources. C. bacchus is traditionally considered to specialise on the dung of large herbivores for both larval and adult feeding. We successfully extracted mammal DNA from 151 adult C. bacchus fecal samples, representing 16 mammal species (ranging from elephants to small rodents), many of which are hitherto undescribed in the diet. Adult C. bacchus showed clear dung source preferences, especially for large herbivores inhabiting dense-cover vegetation. Our approach also confirmed the presence of cryptic taxa in the study area, and we propose that this may be used for biodiversity survey and monitoring purposes. Murid rodent feces were the most commonly fed-upon dung source (77.5%) for adult C. bacchus, differing markedly from the large and megaherbivore dung sources used for larval rearing. These findings support the hypothesis of life history-specific shifts in resource use in dung beetles, and reveal a hitherto unsuspected, but ecologically important, role of these dung beetles in consuming rodent feces. The differences in feeding abilities of the larval and adult life history stages have profound consequences for their resource use and foraging strategies, and hence the ecological role of dung beetles. This principle and its ecological consequences should be explored in other scarabaeids.

The Contribution of the Chacma Baboon to Seed Dispersal in the Eastern Karoo, South Africa

Maintaining key ecological processes is a strong argument for conserving biodiversity, and this should extend to preventing the local extinction of keystone species that are otherwise common. Seed dispersal is such a process and chacma baboons (Papio ursinus ursinus) may facilitate seed dispersal, but currently suffer range contractions in South Africa. Between April 2016 and February 2017, we collected a total of 122 chacma baboon scat samples in a semi-arid subtropical thicket, South Africa, and identified food items and seeds from the scats. We show that chacma baboons are omnivores, able to disperse at least 24 different seed species. This is a wider range of seed species than those dispersed by a broad range of birds, reptiles or other mammals in subtropical thicket, and nearly five times that dispersed by domestic goats (Capra hircus). This suggests that baboons are key seed dispersers, whose role might not be substituted by goats. We believe that baboons may become more important seed dispersers in arid subtropical thicket as climate change alters the distributional ranges of plant communities. This important role as endo-zoochores highlights the need to conserve, rather than persecute, chacma baboons.