Landscape-scale feeding patterns of African elephant inferred from carbon isotope analysis of feces

Abstract

The African elephant (Loxodonta africana) is a large-bodied, generalist herbivore that eats both browse and grass. The proportions of browse and grass consumed are largely expected to reflect the relative availability of these resources. We investigated variations in browse (C(3) biomass) and grass (C(4)) intake of the African elephant across seasons and habitats by stable carbon isotope analysis of elephant feces collected from Kruger National Park, South Africa. The results reflect a shift in diet from higher C(4) grass intake during wet season months to more C(3) browse-dominated diets in the dry season. Seasonal trends were correlated with changes in rainfall and with nitrogen (%N) content of available grasses, supporting predictions that grass is favored when its availability and nutritional value increase. However, switches to dry season browsing were significantly smaller in woodland and grassland habitats where tree communities are dominated by mopane (Colophospermum mopane), suggesting that grasses were favored here even in the dry season. Regional differences in diet did not reflect differences in grass biomass, tree density, or canopy cover. There was a consistent relationship between %C(4) intake and tree species diversity, implying that extensive browsing is avoided in habitats characterized by low tree species diversity and strong dominance patterns, i.e., mopane-dominated habitats. Although mopane is known to be a preferred species, maintaining dietary diversity appears to be a constraint to elephants, which they can overcome by supplementing their diets with less abundant resources (dry season grass). Such variations in feeding behavior likely influence the degree of impact on plant communities and can therefore provide key information for managing elephants over large, spatially diverse, areas.

Seasonal diet changes in elephant and impala in mopane woodland

“…For example, Prins et al (2006) show that small differences in diet can have large consequences for diet breadth, diet overlap and segregation between species and hence influence interspecific competition. Our finding that elephant changed their diet to more dicots in the dry season is supported by other studies (Hansen et al 1985;Cerling et al 2006;Codron et al 2006;2011). Impalas are mainly grazers in the wet season and only change their diet to a higher percentage of dicots (while maintaining their monocot-dominated diet) when the monocots are of such low quality that it is more profitable to eat more dicots.…”

“…Also, in other studies, mopane has been suggested to be an important food source for elephants due to its high quality and abundance (Styles and Skinner 2000;Ben-Shahar and Macdonald 2002;Holdo 2003). The importance of mopane in the diet of elephant in this study is in contrast with the findings of Codron et al (2006) and Codron et al (2011). In the first study, the authors suggested that mopane may deter feeding as a result of high percentages of secondary compounds and force elephant to forage on grasses (Codron et al 2006).…”

“…In the first study, the authors suggested that mopane may deter feeding as a result of high percentages of secondary compounds and force elephant to forage on grasses (Codron et al 2006). In the second study, the authors suggested that in a mopane-dominated area, where diversity of browse species is low, elephants need to maintain dietary diversity and therefore feed less on mopane (Codron et al 2011). However, our data indicate that mopane is indeed the most important browse species in the diet of elephants and that this species constitutes 65% of the diet after the diet switch.…”

Incorporating mortality into habitat selection to identify secure and risky habitats for savannah elephants

“…The dry season is the limiting season for this mega-herbivore (Illius, 2006;Trimble et al, 2009), so we consider the dry season best reflects limitations in habitat suitability and ultimately best relates to fitness. Habitat selection patterns are likely to vary in the core wet season (Young et al, 2009), when elephants shift their diet to consume more grasses (Cerling et al, 2006;Codron et al, 2011) and are less dependent on permanent water sources (Harris et al, 2008;Young et al, 2009). Based on our knowledge of elephant use patterns in the area from GPS collar data, we suspect that areas designated as "non-habitat" will be most influenced, particularly in NG-north.…”

Isotopic paleoecology of Clovis mammoths from Arizona

“…However, little else is known about seasonality in the Late Pleistocene SPV or how it affected mammoth ecology. Climate exerts a strong influence on modern elephant diet and migration patterns (21)(22)(23)(24), and the same was likely true for mammoths.…”