Monitoring spatiotemporal dynamics of large herbivores across an African rangeland using hierarchical multi-species distance sampling

Abstract

A relative lack of standardised long-term monitoring data often limits the ability of African conservancies to quantify their efficacy to protect wildlife. In this study, we combined eight 2-km long transects surveyed monthly between October 2017 and March 2020 (total 240 transects sampled) with a hierarchical multi-species and multi-season distance sampling modelling framework to: (1) estimate monthly density of an ensemble of 10 different large herbivores and (2) understand how species respond to changes in vegetation productivity and time across the Naboisho Conservancy in the Greater Mara Ecosystem, Kenya. We documented a total of 55,298 individuals from 6830 animal groups. The median coefficient of variation for all density estimates was 27.67%. On average, number of groups was higher at intermediate levels of vegetation productivity. We found that in general, populations of large herbivores remained stable in the conservancy during the study period, except for wildebeest which decreased in density. We showed that multi-species monitoring frameworks can be used to understand how species abundance changes across space and time, providing indications as to how they are responding to environmental dynamics or management prescriptions—both of which are valuable tools for under-resourced wildlife conservancies.