Non-Analog Behaviour of Eastern African Herbivore Communities During the Last Glacial Period

Abstract

Modern African ungulates navigate seasonal variation in resource availability through diet-switching (primarily mixed-feeders) and/or migrating (primarily grass grazers). These ecological generalisations are well-documented today, but the extent to which they apply to the non-analog ecosystems of the Pleistocene are unclear. Drawing from serially-sampled stable isotope measurements from 18 Kenyan large herbivore species from the Last Glacial Period (LGP), we evaluate how diet, diet-switching, and migration compare to observations from present-day settings. We find a higher grazing signal in most LGP species and a greater magnitude of diet-switching than in the present. Additionally, we find that the relationships between grass intake, migration, diet-switching, and body size during the LGP were unlike those observed today. This establishes a revised paleoecology of LGP herbivore communities and highlights that LGP herbivores were behaviourally non-analog. Our results imply that ecological observations from present-day settings offer an incomplete perspective of herbivore-environment interactions.