Habitat use strategies of African elephants under different seasonal and ecological constraints

Abstract

CONTEXT : Habitat selection is a fundamental process that shapes animal spatial ecology. Species with wide geographic distribution that occupy diverse habitats have to adapt their resource acquisition strategies to maximise their effectiveness under local ecological constraints, leading to intraspecific behavioural variability. Identifying environmental determinants of habitat use pattern and regional intraspecific differences advances our understanding of the ecological underpinnings of animal behaviour and is important in strategising effective conservation and management of free-ranging populations.

AIMS : The aim of this study was to assess individual heterogeneity of habitat selection and use by African elephants under different seasonal and ecological constraints, in order to better understand the processes underlying their spatial behaviour.

METHODS : We investigated the habitat selection pattern of 19 African elephants equipped with satellite-linked GPS-collars in two different ecosystems, resource-rich bushveld bordering Kruger National Park, South Africa (six individuals) and arid savannah of Etosha National Park, Namibia (13 individuals). By constructing individual-specific and population-level resource selection functions (RSFs), we examined seasonal differences of elephant habitat use pattern to identify the underlying ecological mechanisms.

KEY RESULTS : Elephants were attracted to surface water in both study areas; but when water availability decreased in arid environment, they showed individual-specific preference in using natural vs artificial water sources. Road networks enabled efficient travel among resource patches, but its use differed between individuals. Areas with higher and more predictable vegetation productivity were generally preferred by elephants in dry season, but in more competitive arid savannah system there were individual/group-specific seasonal differences in resource selection patterns, likely reflecting the social dynamics among individuals. At population-level, the habitat selection pattern was less apparent due to considerable intra-population variability.

CONCLUSIONS : The substantial differences in model coefficients within and between our study populations demonstrate the spatio-behavioural plasticity of elephants under various environmental conditions and suggest that population-level RSFs may over-simplify elephants’ socio-ecological complexity.

IMPLICATIONS : Within the resource competition paradigm, individual-specific habitat selection may be as essential in maintaining population resilience as is the population-level pattern of resource use. Consequently, spatio-behavioural heterogeneity within and between populations should be accounted for in resource selection studies and all subsequent conservation management policies.