Northern white-faced owls are small. When faced with a bigger, more threatening owl, they react with extreme physical transformations, either puffing out into a large fan of feathers or—if their opponent is too big to intimidate—compressing themselves to imitate a tree branch.
Owls’ night-vision eyes are striking in their enormity, weighing up to 5 percent of the birds’ total body mass. Their direct stare is a function of their physiology, since their eyes don’t move in the sockets. But the birds make up for it by being able to swivel their heads up to 270 degrees in either direction.