/ 6 January 2006

Crop-raiding elephants under surveillance

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’ behaviour, 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,” said Henrik Rasmussen, a conservationist at Oxford University who took part in the study. ”Sometimes the elephants are spotted and shot in the act.”

The scientists tracked a herd of seven elephants by fitting them with global positioning system 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. Elephant hairs grow about 0,5mm a day and ratios of chemicals in the hairs vary depending on the type of food the elephant is eating at the time.

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 his 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 January 2.

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 gunshot wounds, likely as a result of crop raiding.”

Rasmussen added: ”Knowing when the raids are most likely to happen, we can work out the best ways to deter the elephants, when fences or other measures are going to be most needed.” — Â