How to ward off hungry birds if you’re a tasty caterpillar? Try to look like something really distasteful: bird poop. Some caterpillars are masters of disguise, fine-tuning their poo mimicry with a grab bag of tricks—using color, pattern, choice of resting place, and, sometimes, contorting their bodies to match the squiggly shape of bird droppings. In a paper published online this month in Animal Behaviour, scientists…