Seed Removal by Rodents and Harvester Ants in the Laikipia District of Central Kenya: a Study of the Evolution of Competition Within Plots of Varying Ungulate Exclusion

Abstract

This thesis explores seed foraging competition between small mammals (Gerbilliscus robustus, Saccostomus meanrsi) and harvester ants (Messor angularis) in the Laikipia district of central Kenya. Due to harvester ants’ natural aversion to high vegetation cover and rain, and small mammals’ preference of such a habitat, I hypothesize that small mammals will be more active in areas of dense vegetation, far from M. angularis nests, which are located in cleared, bareground areas. Furthermore, because I am testing out my hypothesis in Large Mammalian Herbivore exclusion plots of the UHURU experiment, I also hypothesize that rodents will dominate seed foraging in total exclusion (LMH) plots, due to increased understory density. I test out these hypotheses using a seed removal experiment, in which I exclude rodents and/or ants (depending on the experiment) from accessing the seeds in petri dishes, and perform multiple experiments with varying distances from the nearest harvester ant nest. My results provide evidence that there is indeed competition between M. angularis and small rodents, and that harvester ants will dominate foraging in areas within 5-10 m of their nest while rodents will dominate in areas of dense vegetation. My hypothesis that rodents dominate seed foraging in LMH plots over harvester ants is also revealed to be significantly sound.