Biting flies flee elephants' swatters.

Elephants make their own fly swatters and use them most frequently in the heat of the day, when biting pests are out in force, a new study finds. Presented at the annual meeting of the Animal Behavior Society in July, the report shows how elephants use their heads - and their trunks- not only to employ a tool, but also to modify and save it. This behavior illustrates the elephant's highly evolved, complex brain, says study coauthor Benjamin L. Hart.

He and Lynette A. Hart, both animal behaviorisis at the University of California, Davis - site of the July meeting - traveled to Nepal, where they observed the swatting behavior of 15 captive Asian elephants. The animals fashioned fly swatters out of whatever they could wrap their trunks around- leafy branches, banana stalks, burlap. Sometimes the elephants altered the branches, shortening sticks or trimming side stems.

Charles Darwin observed elephants swatting flies in 1871, but his and other reports remained isolated sitings. The new study is the first to systematically document tool use in elephants, Benjamin Hart says.