Soil ingestion, nutrition and the seasonality of anthrax in herbivores of Etosha National Park

Abstract. Anthrax, caused by the bacterium Bacillus anthracis, is a seasonally occurring infectious disease affecting primarily herbivorous wildlife and livestock. The seasonality of anthrax outbreaks varies among locations, making it difficult to develop a single consistent ecological description of this disease. Over 44 years of mortality surveillance, most anthrax cases in Etosha National Park, Namibia are observed in the wet season, although elephants have an anthrax mortality peak in the dry season. Focusing on three host species (plains zebra, Equus quagga; African elephant, Loxodonta africana; and springbok, Antidorcas marsupialis) occupying the endemic anthrax area of Etosha National Park, Namibia, we tested two commonly posited causes of anthrax seasonality in herbivores: increased pathogen exposure due to greater soil contact, and increased host susceptibility due to seasonal nutritional stress. These hypotheses were assessed using fecal sampling and measurement of the percentage of fecal silicates as an index of soil ingestion and fecal nitrogen, phosphorus and crude fiber as nutritional indices. Nutritional quality for all three species was higher in wet than dry seasons. Comparing among wet seasons, nutritional indices showed either a decline in nutrition with increasing rainfall or no significant pattern. All three species had greater soil ingestion in the wet season than the dry season. Higher soil contact during the anthrax peak suggests that anthrax seasonality may in part be due to heightened exposure to B. anthracis in wet seasons, for zebra and springbok. Elephant anthrax deaths do not correspond with the season of increased soil ingestion or grazing, suggesting that other behavioral mechanisms may overshadow foraging-based risk factors for this species. Nutritional stress is unlikely the primary causative factor in wet season anthrax systems, although nutritional stress sufficient to reduce resistance is difficult to assess non-invasively in wild herbivores. In contrast, increased soil ingestion may be an important predisposing factor for wet season anthrax outbreaks. Ultimately, the amount of soil ingested and its importance in the transmission of soil-borne pathogens will vary based on foraging behaviors, intake rates, grassland structure and on the likelihood that foraging areas intersect with pathogen aggregations in the environment

Variation in herbivore space use: comparing two savanna ecosystems with different anthrax outbreak patterns in southern Africa

Abstract Background The distribution of resources can affect animal range sizes, which in turn may alter infectious disease dynamics in heterogenous environments. The risk of pathogen exposure or the spatial extent of outbreaks may vary with host range size. This study examined the range sizes of herbivorous anthrax host species in two ecosystems and relationships between spatial movement behavior and patterns of disease outbreaks for a multi-host environmentally transmitted pathogen. Methods We examined range sizes for seven host species and the spatial extent of anthrax outbreaks in Etosha National Park, Namibia and Kruger National Park, South Africa, where the main host species and outbreak sizes differ. We evaluated host range sizes using the local convex hull method at different temporal scales, within-individual temporal range overlap, and relationships between ranging behavior and species contributions to anthrax cases in each park. We estimated the spatial extent of annual anthrax mortalities and evaluated whether the extent was correlated with case numbers of a given host species. Results Range size differences among species were not linearly related to anthrax case numbers. In Kruger the main host species had small range sizes and high range overlap, which may heighten exposure when outbreaks occur within their ranges. However, different patterns were observed in Etosha, where the main host species had large range sizes and relatively little overlap. The spatial extent of anthrax mortalities was similar between parks but less variable in Etosha than Kruger. In Kruger outbreaks varied from small local clusters to large areas and the spatial extent correlated with case numbers and species affected. Secondary host species contributed relatively few cases to outbreaks; however, for these species with large range sizes, case numbers positively correlated with outbreak extent. Conclusions Our results provide new information on the spatiotemporal structuring of ranging movements of anthrax host species in two ecosystems. The results linking anthrax dynamics to host space use are correlative, yet suggest that, though partial and proximate, host range size and overlap may be contributing factors in outbreak characteristics for environmentally transmitted pathogens

The use of focus group discussion methodology: Insights from two decades of application in conservation

This is the final version of the article. Available from Wiley via the DOI in this recordFocus group discussion is frequently used as a qualitative approach to gain an in-depth understanding of social issues. The method aims to obtain data from a purposely selected group of individuals rather than from a statistically representative sample of a broader population. Even though the application of this method in conservation research has been extensive, there are no critical assessment of the application of the technique. In addition, there are no readily available guidelines for conservation researchers. Here, we reviewed the applications of focus group discussion within biodiversity and conservation research between 1996 and April 2017. We begin with a brief explanation of the technique for first-time users. We then discuss in detail the empirical applications of this technique in conservation based on a structured literature review (using Scopus). The screening process resulted in 170 articles, the majority of which (67%, n = 114,) were published between 2011 and 2017. Rarely was the method used as a stand-alone technique. The number of participants per focus group (where reported) ranged from 3 to 21 participants with a median of 10 participants. There were seven (median) focus group meetings per study. Focus group discussion sessions lasted for 90 (median) minutes. Four main themes emerged from the review: understanding of people's perspectives regarding conservation (32%), followed by the assessment of conservation and livelihoods practices (21%), examination of challenges and impacts of resource management interventions (19%) and documenting the value of indigenous knowledge systems (16%). Most of the studies were in Africa (n = 76), followed by Asia (n = 44), and Europe (n = 30). We noted serious gaps in the reporting of the methodological details in the reviewed papers. More than half of the studies (n = 101) did not report the sample size and group size (n = 93), whereas 54 studies did not mention the number of focus group discussion sessions while reporting results. Rarely have the studies provided any information on the rationale for choosing the technique. We have provided guidelines to improve the standard of reporting and future application of the technique for conservation.N.T.O. was funded by Cambridge Overseas Trusts, The Wildlife Conservation Society, Wildlife Conservation Network and WildiZe Foundation. NM was funded by the NERC grant (NE/R006946/1), Fondation Wiener Anspach and the Scriven post doctoral fellowships. K.W. was sup-ported by the Australian Research Council Centre of Excellence for Environmental Decisions (CE11001000104) and Future Fellowship (FT100100413) programs and funded by the Australian Government

Africa’s drylands in a changing world : challenges for wildlife conservation under climate and land-use changes in the greater Etosha landscape

Proclaimed in 1907, Etosha National Park in northern Namibia is an iconic dryland system with a rich history of wildlife conservation and research. A recent research symposium on wildlife conservation in the Greater Etosha Landscape (GEL) highlighted increased concern of how intensification of global change will affect wildlife conservation based on participant responses to a questionnaire. The GEL includes Etosha and surrounding areas, the latter divided by a veterinary fence into large, private farms to the south and communal areas of residential and farming land to the north. Here, we leverage our knowledge of this ecosystem to provide insight into the broader challenges facing wildlife conservation in this vulnerable dryland environment. We first look backward, summarizing the history of wildlife conservation and research trends in the GEL based on a literature review, providing a broad-scale understanding of the socioecological processes that drive dryland system dynamics. We then look forward, focusing on eight key areas of challenge and opportunity for this ecosystem: climate change, water availability and quality, vegetation and fire management, adaptability of wildlife populations, disease risk, human-wildlife conflict, wildlife crime, and human dimensions of wildlife conservation. Using this model system, we summarize key lessons and identify critical threats highlighting future research needs to support wildlife management. Research in the GEL has followed a trajectory seen elsewhere reflecting an increase in complexity and integration across biological scales over time. Yet, despite these trends, a gap exists between the scope of recent research efforts and the needs of wildlife conservation to adapt to climate and land-use changes. Given the complex nature of climate change, in addition to locally existing system stressors, a framework of forward-thinking adaptive management to address these challenges, supported by integrative and multidisciplinary research could be beneficial. One critical area for growth is to better integrate research and wildlife management across land-use types. Such efforts have the potential to support wildlife conservation efforts and human development goals, while building resilience against the impacts of climate change. While our conclusions reflect the specifics of the GEL ecosystem, they have direct relevance for other African dryland systems impacted by global change.DATA ACCESSIBILITY STATEMENT: Additional information about datasets and reports from the Etosha Ecological Institute can be obtained from Claudine Cloete ([email protected]). Additional information about the literature review can be obtained from Stéphanie Périquet ([email protected]).https://www.elsevier.com/locate/geccoMammal Research InstituteZoology and Entomolog

Africa’s drylands in a changing world : challenges for wildlife conservation under climate and land-use changes in the Greater Etosha Landscape

Proclaimed in 1907, Etosha National Park in northern Namibia is an iconic dryland system with a rich history of wildlife conservation and research. A recent research symposium on wildlife conservation in the Greater Etosha Landscape (GEL) highlighted increased concern of how intensification of global change will affect wildlife conservation based on participant responses to a questionnaire. The GEL includes Etosha and surrounding areas, the latter divided by a veterinary fence into large, private farms to the south and communal areas of residential and farming land to the north. Here, we leverage our knowledge of this ecosystem to provide insight into the broader challenges facing wildlife conservation in this vulnerable dryland environment. We first look backward, summarizing the history of wildlife conservation and research trends in the GEL based on a literature review, providing a broad-scale understanding of the socioecological processes that drive dryland system dynamics. We then look forward, focusing on eight key areas of challenge and opportunity for this ecosystem: climate change, water availability and quality, vegetation and fire management, adaptability of wildlife populations, disease risk, human-wildlife conflict, wildlife crime, and human dimensions of wildlife conservation. Using this model system, we summarize key lessons and identify critical threats highlighting future research needs to support wildlife management. Research in the GEL has followed a trajectory seen elsewhere reflecting an increase in complexity and integration across biological scales over time. Yet, despite these trends, a gap exists between the scope of recent research efforts and the needs of wildlife conservation to adapt to climate and land-use changes. Given the complex nature of climate change, in addition to locally existing system stressors, a framework of forward-thinking adaptive management to address these challenges, supported by integrative and multidisciplinary research could be beneficial. One critical area for growth is to better integrate research and wildlife management across land-use types. Such efforts have the potential to support wildlife conservation efforts and human development goals, while building resilience against the impacts of climate change. While our conclusions reflect the specifics of the GEL ecosystem, they have direct relevance for other African dryland systems impacted by global change.Publisher PDFPeer reviewe