Foraging by elephant, giraffe and impala during wet and dry season in rich and poor savanna, Tanzania

Abstract

Plant have evolved traits in response to herbivory and these traits depends on soil nutrient status, plants in nutrient rich soils have evolved tolerance to herbivory by being palatable and those in nutrient poor have evolved to avoid and prevent future herbivory by being unpalatable. This condition influence interactions between elephant a mega-herbivore with browsers (giraffe) and mixed-feeders (impala) as their interaction depends on food availability. Serengeti National Park is nutrient rich habitat while Mikumi National Park is nutrient poor habitat. My study aimed to observe impacts of elephant foraging to giraffe a browser and impala a mixed-feeder in these two habitats with different soil nutrient status during wet and dry season. Data collected from April to May for the wet season and august to September, 2014 for dry season, overlap in food resource use was calculated using Schoener`s overlap index. Elephant did not overlap with giraffe and impala in food resource use in either Serengeti nutrient rich soils or Mikumi nutrient poor soils in both wet and dry season. Overlap observed was between giraffe and impala in Serengeti on dry season. Absence of overlap between elephants and these ungulates was contributed by reliance of elephants on grazing rather than browsing particularly in the wet season signifying influence of season in selectivity of food by elephant and impala.