Plantation owners profit by not persecuting primates

PALM OIL is a lucrative business, but not without its problems. Plantations of palms, the fruit of which are crushed to release the oil, are usually there at the expense of rainforest. This does not go down well with environmentalists. Nor does it go down well with the rainforest’s inhabitants, some of whom, such as pig-tailed macaques, a species of monkey, raid the plantations to eat the palm fruit before it can be harvested.Such raiding, naturally, invites retaliation by planters, who try to trap and relocate the animals, or scare them off with gunshots. But a study published in this week, by Nadine Ruppert and Anna Holzner of the University of Sciences Malaysia, suggests such retaliation is a mistake. Far from driving monkeys away, plantation owners should welcome them, because monkeys help control a yet more important pest of oil palms—rats.