Elephants, Giraffes, and Rhinos Face a Hidden Salt Shortage

In several parts of Africa, some of the continent’s largest herbivores are struggling to obtain enough salt, according to new research.

Sodium is essential for herbivores, as it plays a vital role in metabolism and overall health. Domesticated animals are often provided with salt or mineral licks to meet this need. Wild animals, however, must rely entirely on the natural sodium available in their environment.

While some regions contain plants and soils rich enough in sodium to meet animals’ needs, other areas are severely lacking. These differences can shape where species live and how far they must travel to find natural salt sources.

A new study conducted with researchers from the University of Zurich reveals that access to sodium is limited for many of the world’s largest wild herbivores, including elephants, giraffes, and rhinos.

To reach this conclusion, scientists combined high-resolution maps showing sodium levels in plants with data on animal population densities and fecal analyses. Because sodium deficiency can be detected directly in feces, the researchers were able to accurately assess the animals’ actual sodium intake.

“Across sub-Saharan Africa, plant sodium availability can vary by a factor of up to 1,000,” says Marcus Clauss, coauthor of the study and codirector of the University Animal Hospital at UZH. “In some regions, wild herbivores simply cannot obtain enough salt from their diet.”

The impact is not the same for all species. The study found that sodium shortages are most severe among megaherbivores—animals with very large body sizes. This supports earlier findings showing that the risk of sodium deficiency increases with body mass.

The research also sheds light on several unusual wildlife behaviors. “In Kenya, elephants enter caves to access sodium-rich rocks, while in the Congo they dig for salt in riverbeds,” explains lead author Andrew Abraham of Northern Arizona University. “Similar behavior is seen in other species—gorillas compete over salty foods, and rhinos, wildebeest, and zebras gather at salt pans in the Kalahari Desert.”

The findings may also help explain why megaherbivores are relatively scarce in West Africa. Although the region is rich in vegetation and biodiversity, populations of large herbivores remain low. The researchers suggest that sodium deficiency, combined with pressures such as overhunting and poor soil fertility, could be a major contributing factor.

The study raises important concerns for conservation efforts. Human activities can create artificial sodium hotspots—such as boreholes in Africa or road salting in northern regions. At the same time, many protected areas are located in sodium-poor environments.