Abstract
Animals and humans regularly make trade-offs between competing objectives. In Addo Elephant National Park (AENP), elephants (Loxodonta africana) trade off selection of resources, while managers balance tourist desires with conservation of elephants and rare plants. Elephant resource selection has been examined in seasonal savannas, but is understudied in aseasonal systems like AENP. Understanding elephant selection may suggest ways to minimise management trade-offs. We evaluated how elephants select vegetation productivity, distance to water, slope and terrain ruggedness across time in AENP and used this information to suggest management strategies that balance the needs of tourists and biodiversity. Resource selection functions with time-interacted covariates were developed for female elephants, using three data sets of daily movement to capture circadian and annual patterns of resource use. Results were predicted in areas of AENP currently unavailable to elephants to explore potential effects of future elephant access. Elephants displayed dynamic resource selection at daily and annual scales to meet competing requirements for resources. In summer, selection patterns generally conformed to those seen in savannas, but these relationships became weaker or reversed in winter. At daily scales, resource selection in the morning differed from that of midday and afternoon, likely reflecting trade-offs between acquiring sufficient forage and water. Dynamic selection strategies exist even in an aseasonal system, with both daily and annual patterns. This reinforces the importance of considering changing resource availability and trade-offs in studies of animal selection.Conservation implications: Guiding tourism based on knowledge of elephant habitat selection may improve viewing success without requiring increased elephant numbers. If AENP managers expand elephant habitat to reduce density, our model predicts where elephant use may concentrate and where botanical reserves may be needed to protect rare plants from elephant impacts.
Highlights
Conservation often involves trade-offs between competing goals and objectives
In Addo Elephant National Park (AENP), South Africa, managers seek to balance the local conservation of African elephants (Loxodonta africana) and the ecological processes they provide with protecting rare plants and providing for tourism
Our results indicate that female elephants in AENP exhibit dynamic patterns of resource selection at both daily and annual scales
Summary
Conservation often involves trade-offs between competing goals and objectives. While trade-offs between biodiversity conservation and human needs have been emphasised (e.g. Hirsch et al 2011; McShane et al 2011), it is important to take into account trade-offs between conserving different aspects of biodiversity. Predictive performance of the top model for each daily data set was assessed both for interpolative ability within the Main Camp – Colchester section of AENP and extrapolative ability using independent data from the collared female elephant in the Nyathi section. Differences in covariate values in the Nyathi section of AENP compared with the Main Camp – Colchester section (Figures 2-A1 and 3-A1) led to exclusion of the Nyathi elephant from the population-level resource selection model, but provided an opportunity to test model predictive performance in an area with differing availability. To visually represent habitat use over time by elephants in AENP, relative habitat suitability was predicted for the Main Camp – Colchester section at a 250 m resolution following Equation 2 in Wilson et al (2014): w(s,t) = exp β × F (t)' X (s,t). The midday model was used in this extrapolation because it was the only model to show robust predictions when extrapolated to the Nyathi area (see the Results section)
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