Functional connectivity within conservation networks: Delineating corridors for African elephants

Abstract

Managing multiple parks, reserves, and conservation areas collectively as conservation networks is a recent, yet growing trend. But in order for these networks to be ecologically viable, the functional connectivity of the landscape must be ensured. We assessed the connectivity between six African savanna elephant populations in southern Africa to test whether existing conservation networks were functioning and to identify other areas that could benefit from being managed as conservation networks. We used resource selection function models to create an index of habitat selection by males and female elephants. We employed this habitat use index as a resistance surface, and applied circuit theory to assess connectivity between adjacent elephant populations within six clusters of protected areas across southern Africa. Circuit theory current flow maps predicted a high likelihood of connectivity in the central portion of our study area (i.e. between the Chobe, Kafue, Luangwa, and Zambezi cluster). Main factors limiting connectivity across the study area were high human density in the east and a lack of surface water in the west. These factors effectively isolate elephants in the Etosha cluster in Namibia and Niassa clusters in Mozambique from the central region. Our models further identified two clusters where elephants might benefit from being managed as part of a conservation network, 1) northern Zambia and Malawi and 2) northern Mozambique.We conclude that using habitat selection and circuit theory models to identify conservation networks is a data-based method that can be applied to other focal species to identify and conserve functional connectivity.

Advances in restoration ecology: rising to the challenges of the coming decades

“…The management of the matrix could determine restoration outcomes for biodiversity, with three core matrix effects (movement and dispersal, resource availability and abiotic environment) being modified by five dimensions: spatial and temporal variation in matrix quality, its spatial scale, the longevity and demographic rates of species relative to the temporal scale of matrix variation, and adaptation (Driscoll et al 2013). Landscape connectivity is increasingly seen as a key conservation and restoration goal, particularly as a strategy to allow biotic movement in response to changing environments (Roever et al 2013, Tambosi et al 2014, Okin et al 2015. Deciding what and where to restore is a key challenge for future landscapescale restoration efforts (McRae et al 2012, Torrubia et al 2014.…”

Mapping resource selection functions in wildlife studies: Concerns and recommendations

“…For example, predicting a species’ distribution has been used to inform endangered species management and habitat conservation efforts (Dzialak et al, 2013; Dzialak, Olson, Harju, Webb, & Winstead, 2012; Fortin, Courtois, Etcheverry, Dussault, & Gingras, 2008; Richardson, Stirling, & Hik, 2005; Roever, Van Aarde, & Leggett, 2013). As one example, such modeling has been employed to address concerns including the evaluation of conservation networks for African elephants ( Loxodonta africana oxyotis ;(Roever et al, 2013).…”

Genetic evidence for spatial structuring in a continuous African elephant (Loxodonta africana) population

“…Our results provide evidence for such a functional landscape linkage. The high nDNA gene flow in conjunction with movement routes with suitable habitat (based on resource selection modelling) identified by Roever et al (2013b) suggest a functional linkage between Chobe (Botswana) and Kafue (Zambia) National Parks. This linkage may be direct or indirect through an intermediate population/populations.…”

“…Furthermore, by integrating a similar genetic approach with other studies that investigate elephant spatial ecology (e.g. Roever et al 2013b), future research may identify ecologically sensible linkages between elephant populations in other southern African countries. Identifying such landscape linkages may be crucial to the success of conservation initiatives considering the current anthropocene era in which space for conservation is becoming an increasingly limited resource.…”

“…The KAZA-TFCA includes 36 protected areas (van Aarde and Jackson 2007) that form part of a larger conservation network spanning across *278,000 km 2 (Metcalfe and Kepe 2008). The elephant population in this region is one of the few that has not been spatially fragmented, where anthropogenic disturbances may have altered some local elephant movements (Chase and Griffin 2009;Roever et al 2013a) but apparently do not limit their movements across international borders (Chase and Griffin 2006;Roever et al 2013b). Additionally, these elephants have not been exposed to management interferences such as culling.…”