"Sometimes, especially in inclement weather, incubating birds continue to cover their eggs while hungry, and even when they would appear to be suffering acutely from a long-continued fast. Many marine birds, especially of the penguin and petrel families, remain on their nests for days or even weeks without eating; and some Emperor Penguins, who incubate single eggs on the ice in the frigid gloom of midwinter at the edge of the Antarctic continent, pass about two months in an absolute fast. Must not birds at times experience gnawing pangs of hunger, while they slowly become emaciated from lack of nourishment?"