Huang, Y.-H., N. Owen-Smith, M.D. Henley, P.L. Kamath, J.W. Kilian, S.O. Ochai, H. van Heerden, J.K.E. Mfune, W.M. Getz, W.C. Turner. 2023. Variation in herbivore space use comparing two savanna ecosystems with different anthrax outbreak patterns in southern Africa. Movement Ecology, 11:46. https://doi.org/10.1186/s40462-023-00385-2
Abstract
Background
The distribution of resources can affect animal range sizes and, hence, may alter infectious disease dynamics in heterogenous environments. The risk of pathogen exposure or the spatial distribution of disease outbreaks may vary as a result of changing host range size. This study examined the host range sizes of mammalian herbivore 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 distribution 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 estimated host range sizes at different temporal scales, individual temporal range overlap, and evaluated relationships between range size and resource availability by species.
Results
The spatial distribution of anthrax mortalities was similar between parks but less variable in Etosha than Kruger, where outbreaks varied from locally clustered to large areas, with more cases and species affected. Herbivore space use differed among species and study areas, with individuals in Etosha having larger ranges than in Kruger due to an inverse relationship between range size and resource productivity. In Kruger the main host species had small range sizes and high range overlap, which may heighten exposure when outbreaks occur in their ranges. In contrast, the main host in Etosha had large range sizes. Case numbers of secondary host species with larger range sizes were positively correlated with the extent of anthrax outbreaks.
Conclusions
Our results provide new information on the spatiotemporal structuring of ranging movements of prominent mammalian herbivores in two savanna ecosystems, with comparative values for four species in both systems. While our anthrax results are correlative, they suggest that differences in host space use may have implications for disease dynamics; and, though partial and proximate, space use factors likely contribute to other factors known to affect disease transmission.
The distribution of resources can affect animal range sizes and, hence, may alter infectious disease dynamics in heterogenous environments. The risk of pathogen exposure or the spatial distribution of disease outbreaks may vary as a result of changing host range size. This study examined the host range sizes of mammalian herbivore 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 distribution 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 estimated host range sizes at different temporal scales, individual temporal range overlap, and evaluated relationships between range size and resource availability by species.
Results
The spatial distribution of anthrax mortalities was similar between parks but less variable in Etosha than Kruger, where outbreaks varied from locally clustered to large areas, with more cases and species affected. Herbivore space use differed among species and study areas, with individuals in Etosha having larger ranges than in Kruger due to an inverse relationship between range size and resource productivity. In Kruger the main host species had small range sizes and high range overlap, which may heighten exposure when outbreaks occur in their ranges. In contrast, the main host in Etosha had large range sizes. Case numbers of secondary host species with larger range sizes were positively correlated with the extent of anthrax outbreaks.
Conclusions
Our results provide new information on the spatiotemporal structuring of ranging movements of prominent mammalian herbivores in two savanna ecosystems, with comparative values for four species in both systems. While our anthrax results are correlative, they suggest that differences in host space use may have implications for disease dynamics; and, though partial and proximate, space use factors likely contribute to other factors known to affect disease transmission.