Grazing Pressure Drives Declines in Threatened Antelopes (Tragelaphus imberbis and Nanger (…)

ABSTRACT

Livestock encroachment into protected areas is a major conservation challenge, but its impacts on specific species are often unclear. We investigated the spatial and temporal association between livestock grazing and the abundance of two threatened antelopes, Tragelaphus imberbis and Nanger soemmerringii, in Mago National Park, Ethiopia. Using stratified seasonal surveys and generalized linear mixed models (GLMMs) with a Negative Binomial distribution, we found a strong negative association between grazing pressure and the abundance of both species. This relationship was nuanced: Tragelaphus imberbis exhibited a significant grazing-by-season interaction, with a more pronounced negative impact during the dry season, while Nanger soemmerringii showed a consistent decline with increasing grazing intensity across both seasons. However, due to the correlative nature of our data and a short two-season temporal scale, we cannot infer direct causation or long-term population dynamics. These findings indicate a strong spatial and seasonal association between livestock grazing and the relative abundance of these threatened antelopes. We frame these results as a foundational hypothesis for targeted, species-specific management strategies, while emphasizing the need for long-term, mechanistic research to isolate grazing effects from other environmental gradients.