You are tense and wary, alert to every rustle and snapped twig. A predator is near, you can sense it. Your heart races; you sweat. Quietly, you reach for a doughnut. Stress speeds up the metabolism of grasshoppers, making them seek out easily digested sugars and carbohydrates for a quick energy boost. This and other results, published in three journals in the past month, could have big implications — not just for prospective prey, but also for the ecosystems they live in.
In more relaxed conditions, many animals opt for high-protein foods that help them to grow and reproduce. But with a predator lurking, they need fuel to quickly feed their amped-up bodies — and to bolt, if needs be. Dror Hawlena, an ecologist at Yale University in New Haven, Connecticut, has been teasing out the ecological ramifications of this predation stress in meadows.