Predation can have cascading, regulatory effects across ecological communities. Knowledge of the diet of predators can therefore provide important information regarding their ecology and conservation, as well as their impacts on prey populations. Using scats collected during 2019–2023 and estimates of prey abundance from aerial surveys, we characterized prey consumption and preferences of the Vulnerable African lion Panthera leo population in Tsavo, Kenya. Biomass models applied to prey frequencies in scats revealed that > 85% of lion diet comprised large ungulates weighing > 150 kg. The Critically Endangered hirola Beatragus hunteri and Endangered Grevy's zebra Equus grevyi (species that were introduced in Tsavo as part of ex situ conservation programmes in the 1960s) were amongst the seven prey species, of 16 detected, that were preferred by lions. Our results potentially indicate a disproportionate impact of lion predation on the small hirola and Grevy's zebra populations. Preferential predation, coupled with high availability of alternative prey, may trap the small populations of hirola and Grevy's zebra within a predator pit. Our findings provide a better understanding of lion diet, optimal foraging and the potential effects predators can have on threatened and rare prey species in an important conservation landscape. Based on our findings, we recommend an observational study of the predation ecology of lions and other predators in this system, to provide information on age- and sex-specific predation rates on hirola and Grevy's zebra for a population viability analysis, to support the management of these two threatened and rare herbivores in Tsavo.

The Critically Endangered hirola Beatragus hunteri exists in two populations, a natural population on the Kenyan–Somali border and a translocated population in Tsavo East National Park, Kenya. The Tsavo population is becoming increasingly important for the survival of the hirola yet its status is unknown and little is understood about the factors that limit its growth. Here we report the size, distribution and demographic parameters of the Tsavo population of hirola and consider whether insufficient suitable habitat could be limiting its growth. The Tsavo population has not increased since 2000, when the last census was carried out, but neither has it significantly decreased. The importance of habitat as a limiting factor is dependent on the hirola's ability to utilize marginal habitat.