Jan. 10, 2006 — A new technique for tracking elephants and what they're eating could help conservationists manage these threatened animals, which sometimes roam beyond their sanctuaries in search of food only to come into conflict with humans.

Thure Cerling of the University of Utah and his colleagues fitted 35 Kenyan elephants with GPS collars and analyzed the chemical signature of carbon and nitrogen in their tails to understand their migration habits.

In a study to be published in the Jan. 10 issue of the Proceedings of the National Academy of Sciences, Cerling detailed the habits of seven of the mammals, one of which traveled frequently through farmland, a behavior that eventually got him shot and killed.

"Humans and elephants want to occupy the same space," said Cerling. "What do we need to do to make it compatible?"

Cerling worked with Iain Douglas-Hamilton of Save the Elephant Fund in Nairobi, Kenya, whose team collared the animals and mapped the wanderings of the seven elephants for two years.

While changing batteries in the elephants' collars, biologists took hair samples from the elephants' tails, which contain the chemical signatures of grasses, trees, and shrubs, among other things, eaten over the course of years.

The scientists found that of the seven elephants, six — two males and four females — remained within the arid lowlands of the Samburu National Reserve, dining mostly on trees and shrubs. In the rainy season, the elephants consumed freshly sprouting grasses.

The seventh elephant, a 40-year-old bull named Lewis, stayed in the Sumburu during the rainy season to graze on the tender grasses, but when the climate grew dry, he migrated 25 to 35 miles into the highlands of Mount Kenya's Imenti Forest, where he indulged not only on shrubs and trees but on the crops of farmers.

"Diet is very important for bull elephants," said Douglas-Hamilton. "If they are to succeed in sexual contests for females, they need high-quality food to build up their strength, hence the reason for high-risk crop raiding."

Unfortunately, Lewis's strategy did not pay off and he was shot and killed, presumably by a farmer.

"The human-animal conflict is a problem that we face everywhere in the elephants' range," said program officer Matthew Lewis, who works in species conservation at the World Wildlife Fund.

Lewis is part of a team using GPS to track pygmy elephants in the dense forests of Borneo to determine what areas should be preserved.

"If we're able to tie together their movement and their behavior, hopefully we can mitigate the conflict," he said.

Cerling and scientists from Save the Elephants Fund are currently working to broaden the scope of their research to include the 28 other collared elephants, a mere fraction of the hundreds of elephants living in the Samburu National Reserve.