HotheadsAprile Pazzo was about to call it a day when she noticed that the penguins she was observing seemed strangely agitated. Pazzo, a wildlife biologist, was in Antarctica studying penguins at a remote, poorly explored area along the coast of the Ross Sea. "I was getting ready to release a penguin I had tagged when I heard a lot of squawking," says Pazzo. "When I looked up, the whole flock had sort of stampeded. They were waddling away faster than I'd ever seen them move." Pazzo waded through the panicked birds to find out what was wrong. She found one...