Mapping potential connections between Southern Africa’s elephant populations

Abstract

Southern Africa spans nearly 7 million km2 and contains approximately 80% of the world’s savannah elephants (Loxodonta africana) mostly living in isolated protected areas. Here we ask what are the prospects for improving the connections between these populations? We combine 1.2 million telemetry observations from 254 elephants with spatial data on environmental factors and human land use across eight southern African countries. Telemetry data show what natural features limit elephant movement and what human factors, including fencing, further prevent or restrict dispersal. The resulting intersection of geospatial data and elephant presences provides a map of suitable landscapes that are environmentally appropriate for elephants and where humans allow elephants to occupy. We explore the environmental and anthropogenic constraints in detail using five case studies. Lastly, we review all the major potential connections that may remain to connect a fragmented elephant metapopulation and document connections that are no longer feasible.

Pasteurella sp. associated with fatal septicaemia in six African elephants

“…The resulting high demand for food in combination with the existing rainfall deficit would have compounded on the expected natural resource scarcities in the dry season. A similar multifactorial explanation could underlie the mortality event in Botswana, where elephants experienced stress from poaching in preceding years 11 and high density (2.31 elephants/km 2 ) due to veterinary fencing that restricts dispersal 10 , 11 , 33 , as well as a dry 2019 10 .…”

Integrating habitat suitability modeling with gene flow improves delineation of landscape connections among African savanna elephants

“…Omniscape uses a moving window to estimate connectivity of surrounding cells in relation to one central cell using a CT approach, reducing the spatial bias introduced by genetic sampling locations (McRae et al, 2016;Landau et al, 2021) in the program Julia (Bezanson et al, 2017). The radius was set to 334 pixels (~300km) to allow for connectivity mapping using a geographic scale relevant to both elephant space use (Loarie et al, 2009b;Roever et al, 2013;Huang et al, 2022) and gene flow (de Flamingh et al, 2018). We evaluated the Omniscape map by comparing Normalized Cumulative Current values at 10,000 locations where elephants were present (occurrence points) to 10,000 random locations (SI Figure 4A).…”

“…The genetic diversity of southern African populations has likely been maintained due to the large size of the surviving elephant populations, long elephant generation times, and dispersal and gene flow across the region (de Flamingh et al, 2018). However, there may have been historical connections that are no longer good candidates for connectivity restoration especially with dynamic landscapes or anthropogenic land conversion (Huang et al, 2022). Given the large home range of elephants, connectivity analyses can help identify effective conservation strategies within both protected and unprotected areas to support population persistence by increasing dispersal, gene flow, genetic diversity, and environmental adaptability (Garant et al, 2007).…”

Protecting and connecting landscapes stabilizes populations of the Endangered savannah elephant

“…Notwithstanding the pros and cons of the core and buffer model, such an arrangement allows connections between populations. In contrast, fences prevent release from overcrowding ( 36 , 37 ), disrupt movement ( 38 , 39 ), and reduce genetic variability ( 40 ). Reestablishing connections and developing corridors mitigate these consequences ( 41 , 42 ) and allow for a functioning metapopulation ( 43 – 45 ).…”

“…Southern Africa has set aside large portions of land for wildlife protection ( 48 ) and thus provides a natural experiment to test variations in protected area design. Home to 70% of Africa’s savannah elephants ( 1 , 2 ), these protected areas are a patchwork of fragments, varying in size, level of protection, and connectivity ( 38 , 49 ). This region can potentially restore a continuous savannah elephant metapopulation and has been studied extensively.…”