Sweat streamed down my back, thorny shrubs cut my arms, and we were losing them again. The wild chimpanzees my colleagues and I had been following for nearly five hours had stopped their grunting, hooting and screeching. Usually these calls helped us follow the animals through Uganda's Kibale Forest. For three large males to quiet abruptly surely meant trouble. Suddenly, as we approached a small clearing, we spotted them standing below a massive fig tree and looking up at a troop of red colobus monkeys eating and playing in the treetop.
The monkeys carried on with their morning meal, oblivious to the three apes below. After appearing for a moment to confer with one another, the chimps split up. While the leader crept toward the fig tree, his compatriots made their way up two neighboring trees in silence. Then, in an instant, the leader rushed up his tree screaming. Leaves showered down as the monkeys frantically tried to evade their attacker. But the chimp had calculated his bluster well: although he failed to capture a monkey himself, one of his partners grabbed a juvenile and made his way down to the forest floor with the young monkey in tow, ready to share his catch.