Salt and large African herbivores ^{CEFR B2}

The study, carried out in collaboration with the University of Zurich, shows that the largest wild herbivores in many parts of Africa face limited access to sodium. Researchers combined high-resolution maps of plant sodium with animal population density data and with fecal analyses; because sodium deficiency is directly detectable in feces, the team could assess animals’ actual sodium intake rather than relying only on habitat models.

Marcus Clauss, codirector at the University Animal Hospital at UZH and coauthor, reports that "Plant sodium availability varies by a factor of 1,000 across sub-Saharan Africa." The results confirm earlier findings that the risk of sodium scarcity increases with body size and is particularly common among megaherbivores. The study names elephants, giraffes and rhinos as species especially affected.

First author Andrew Abraham gives behavioural examples that fit the findings: in Kenya elephants enter caves to reach sodium-rich rock, in the Congo they dig for salt in riverbeds, gorillas fight over particularly salty foods, and rhinos, wildebeest and zebras gather at salt pans in the Kalahari. The authors suggest sodium limits probably work together with overhunting and poor soil fertility to explain why megaherbivores are scarce in parts of West Africa despite abundant vegetation.

For conservation the team notes an additional risk: boreholes and road salting create artificial sodium hotspots. Because many protected areas are in low-sodium regions, animals that travel long distances to seek salt could come into conflict with humans more often in the future. The work appears in Nature Ecology & Evolution (Source: University of Zurich).