Burrowing owl chicks mimick the sound of rattlesnakes to scare predators away; fulmar chicks vomit a stomach oil that can ruin the feathers of predatory birds; cuckoos imitate the appearance of the dangerous Sparrowhawk; many owls puff up their feathers to make themselves look bigger and more menacing; ostriches, cassowaries and emus can deliver powerful kicks with their claws and can seriously wound enemies; hoatzin chicks dive into rivers to escape predators, then climb back to their nest using special claws in their wings; ferruginous pygmy owls have spots resembling eyes in the back of their head to trick predators into thinking that they are looking their way; potoos, nightjars and some owls mimic a tree branch or stump with their bark-like feathers and by staying very still; hoopoes squirt feces at their enemies, and most birds can simply fly away from danger!