Elephants roaming the parched plains of Africa's national parks can get up to half their food by risky midnight raids into crop fields, according to scientists who tracked a herd by satellite monitoring.
Conservationists working for Save the Elephants Foundation in Kenya hope that by understanding the elephants' behavior, they can improve ways of protecting farmers against damage caused by the animals, and in turn protect the elephants from angered farmers.
"When an elephant raids a crop field, it can be devastating for a farmer. Sometimes the elephants are spotted and shot in the act," said Henrik Rasmussen, a conservationist at Oxford University who took part in the study.
The scientists tracked a herd of seven elephants by fitting them with GPS satellite tags as they wandered through the Samburu national reserve in Kenya. Tension between the local population and elephants has worsened in recent years as small-scale farmers have encroached on the parkland to grow crops.
By combining information on the elephants' movements with chemical tests on hairs plucked from their tails, the researchers recreated the elephants' routes and also worked out what they ate along the way.
The tail hair of six of the elephants indicated that they spent most of their time in the arid lowlands of Samburu eating trees and shrubs. During the rainy season they switched to grasses.
The seventh elephant, named Lewis, was different. He spent rainy seasons in lowland Samburu, but then trekked 40km to the Imenti Forest, 2,000m above sea level on Mount Kenya. From here, he made repeated night-time raids into subsistence farms during the dry period from mid-June to mid-August. Tests on tail hairs suggest that between a third and a half of Lewis's food intake was corn from the farmland, according to the report in Proceedings of the National Academy of Sciences, published on Monday.
Iain Douglas-Hamilton, president of the foundation and the study's lead author, said crop raids are extremely dangerous.
"It is a high-risk, high-gain strategy, and in our elephant's case it did not pay off. Shortly after the research was done, Lewis suffered multiple gunshots, very likely as a result of crop raiding," he said.