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

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 disease outbreaks may vary with host range size. This study examined the range sizes of herbivorous anthrax host species in two ecosystems with different observed patterns for disease outbreaks of a multi-host environmentally transmitted pathogen. Methods We examined the spatial extent of anthrax outbreaks and range sizes for seven host species in Etosha National Park, Namibia and Kruger National Park, South Africa, where the main host species and outbreak sizes differ. We estimated the spatial extent of annual anthrax mortalities using the local convex hull (LoCoH) method and evaluated whether outbreak distribution was correlated with case numbers of a given host species. We evaluated host range sizes at different temporal scales, within-individual temporal range overlap, and relationships between range size and resource availability by species. Results 1. The spatial extent of anthrax mortalities was similar between parks but less variable in Etosha than Kruger, where outbreaks varied from locally clustered to large areas with the spatial extent correlated with numbers of cases and species affected. 2. Case numbers of secondary host species with larger range sizes were positively correlated with the spatial extent of anthrax outbreaks in both parks. 3. Host space use differed among species and study areas, with individuals in Etosha having larger ranges than in Kruger possibly due to an inverse relationship between range size and resource productivity. 4. In Kruger, the main host species had small range sizes and high range overlap, which may heighten exposure when outbreaks occur in their ranges. However, different patterns were observed in Etosha, where the main host species had large range sizes and relatively little range overlap. Conclusions Our results provide new information on the spatiotemporal structuring of ranging movements of anthrax host species. The results linking anthrax dynamics to host range sizes are correlative, yet suggest that, though partial and proximate, host range size and overlap may be contributing factors in disease outbreak dynamics for environmentally transmitted pathogens.These files include: 1. Thinned movement datasets 2. Shapefiles for Etosha and Kruger boundaries and pains in Etosha 3. R code for analysesFunding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: DEB-1816161/DEB-2106221We compiled movement data from GPS (Global Positioning System) collars including newly collected and previously published datasets on springbok (Antidorcas marsupialis) from Etosha National Park, Namibia, impala (Aepyceros melampus) and African buffalo (Syncerus caffer) from Kruger National Park, South Africa, and greater kudu (Tragelaphus strepsiceros), blue wildebeest (Connochaetes taurinus), and plains zebra (Equus quagga) from both parks between 2006 – 2020. Newly collected data included movement datasets on kudu, wildebeest and zebra (2018–2020) in Etosha and impala and kudu in Kruger. Details of the numbers, time periods and data sources of these movement data can be found in the corresponding research paper. Because of different sampling intensities and irregular intervals of the telemetry data, we thinned the data to three readings a day for more comparable relocation data across different species and tracking periods among species. We then prepared three different datasets at bimonthly, monthly and seasonal scales for each species by park and further prepared a fourth dataset at seasonal scales with only individuals tracked across at least three seasons. Details of dataset preparation can be found in the corresponding paper. The data here are thinned movement datasets