The Lion's Share: Implications of carnivore diet on endangered herbivores in Tsavo

Abstract

Predation by mammalian carnivores can have cascading, regulatory effects across ecological communities. An understanding of predator diet can therefore provide crucial information regarding their ecology and conservation, as well as their impacts on prey populations. Using scats collected between 2019 and 2023, coupled with estimates of prey abundance from aerial surveys, we characterized lion prey-consumption and preference in Tsavo, Kenya. A lion-specific biomass model applied to prey frequencies in scats revealed that more than 85% of lion diet consisted of large ungulates weighing over 150 kg. While large ungulates were also preferred prey items in terms of their availability, we found a disproportionately high consumption and preference of lions for the endangered hirola and Grevys zebra-- species that were introduced in Tsavo as part of ex-situ conservation programs. Hirola and Grevys zebra populations have historically remained small in Tsavo despite strong recovery efforts, and our results likely indicate a disproportionate impact of lion predation on these small but crucial populations. Preferential predation, coupled with high availability of alternative prey, may trap hirola and Grevys zebra within a predator-pit. Our findings have strong implications for understanding lion diet, optimal foraging, and the potential effects predators have on endangered prey species in a landscape of critical conservation importance.