Talk about a badass beak. This shoe-billed stork lives primarily in swamps from Sudan to Zambia. The bill itself takes 1.5 months from hatching to fully develop into its slipper-like shape. But some think it's the most frightening bird on the planet, as chicks are known to fight each other off to the death with even Mom picking favorites. The five-foot birds are also known to be patient hunters that rip their prey apart, including crocodiles.