Kenya's Mount Elgon Elephants Appear to Treat Themselves With Medicinal Plants

Wild African elephants on Kenya's Mount Elgon appear to seek out specific plants when they are sick, and mother elephants may even feed plant "medicine" to their calves, according to a study published in Scientific Reports that systematically documents the behavior for the first time.

The research was led by Fabien Schultz, head of the junior research group in ethnopharmacology and zoopharmacognosy at the Bernhard Nocht Institute for Tropical Medicine in Hamburg, Germany. It was carried out with the Mount Elgon Foundation, Neubrandenburg University of Applied Sciences, the East African Wild Life Society's Mount Elgon Elephant Project, the National Museums of Kenya and other local partners. Scientists have known since the 1970s that some animals treat themselves, a field called zoopharmacognosy. Chimpanzees swallow bitter leaves to fight intestinal parasites, and some birds line nests with insecticidal plants. Earlier work hinted at self-medication in Asian elephants, but systematic studies of African elephants have been rare.

Rather than disturb the animals, the team relied on people who have lived beside them for decades. The researchers interviewed eight local experts, including wildlife scouts, a former ranger, a retired agricultural officer who grew up on the mountain and community elders, each with more than 20 years of experience with the herds. The experts described which plants the elephants eat when they show signs of illness. The team then collected herbarium specimens of every plant mentioned, had them identified at the East African Herbarium and checked the scientific literature for known pharmacological effects.

In total, the experts named 39 natural resources they believe the elephants use on purpose: 35 plant species from 23 families plus four types of soil, mineral or clay. In 34 cases, or 87%, local people also use the same resource in traditional medicine. Twenty-five were explicitly described as "medicine for elephants." The strongest cases fell into what the researchers call "Mode 4": sick animals eating small amounts of something neither nutritious nor tasty, at unusual times or in unusual ways. Eight plants met those criteria, including Aloe arborescens, Bersama abyssinica and Ficus natalensis. Several interviewees described elephants walking long distances straight to a particular tree, without feeding along the way, just to eat its bark or leaves. Some of these plants have previously shown antibacterial, anti-inflammatory or antiparasitic properties in lab studies.

The most striking accounts involved mothers giving plant material to their calves. Five resources came up in reports of this mother-to-calf care. The team is now trying to capture it on video, and the authors stress that neither the preparation nor any health benefit has been proven. Mount Elgon's elephants are also famous for mining salt, entering caves as deep as 160 meters, or 525 feet, to eat mineral-rich rock. The Mount Elgon Foundation has documented 55 caves the elephants use. The study supports the view that the animals eat clay both for minerals and to protect their digestion, but stops short of calling it medicine.

"Our results show how closely the plant life of Mount Elgon is linked to the health of both elephants and people," Schultz said. "Reports that elephants use some of the same plants that local communities use in traditional medicine make protecting these habitats a One Health issue." Co-corresponding author Elodie Freymann, who studies self-medication in great apes, put it more simply: "Most of the time the people who live in close proximity to animals have known their secrets for generations. Our job as scientists is now to start asking the right questions."

The findings carry a conservation message. African elephants are threatened by habitat loss and conflict with people. If they depend on particular medicinal plants, the authors argue, then clearing forest removes not just food but part of their pharmacy. The team next plans to test the plants' chemistry for antimicrobial, anti-inflammatory and antiparasitic effects and to study whether the behavior is learned and passed between generations.