Water and wildlife in the Serengeti-Mara ecosystem

Surface water is a key resource for wildlife conservation and its spatial and temporal distribution is important in understanding the distribution and composition of large herbivore assemblages in savannah ecosystems. Unprecedented continual decline in surface water availability in these ecosystems pose a threat to ungulates abundance and landscape use. But how changes in surface water will affect large herbivores has inadequately been investigated. Here we quantified drivers of changes in surface water in the Serengeti-Mara ecosystem and furthermore quantified changes in surface water availability affect the distribution and composition of large herbivore communities. We studied how fire and livestock grazing affect surface water availability and subsequently wildlife landscape use. Furthermore, we quantified water requirements of savannah ungulates using six different functional traits related to water loss pathways. We found that between 1972 and 2018, human activities upstream and outside protected area have changed the recession time scale for Mara River while the lack of human activities in the Serengeti National Park has maintained the hydrological properties of the Mbalageti River. Furthermore, we observed a wide range of water requirements among ungulates with two major groups of water dependent and independent species. In addition, this study provides evidence that each functional trait can be independently used to predict water requirements and in particular proposes that minimum dung moisture content is an easy to measure index of water requirement. Importantly, we showed that water requirements add a new dimension of niche partitioning for grazing ungulates that is independent of body size