Between 1840 and 1880, guano nitrogen made a vast difference to European agriculture.

ECONOMIST: The story of man's staple food

In the dry uplands of Chile, rich mineral nitrate deposits were then found, and gradually took the place of guano in the late 19th century.

ECONOMIST: The story of man's staple food

By 1850, Ichaboe, minus 800, 000 tonnes of guano, was deserted again.

ECONOMIST: The story of wheat: Ears of plenty | The

They waddle down to the water to wash off the rust-colored guano that stains their pelts and produces a pungent odor that within days becomes expected with each landing.

FORBES: Go with the Floe

By combining monochromatic and color images to sharpen the focus of the satellite imagery, the science teams were able to then differentiate between birds, guano and shadow.

WSJ: Emperor Penguins Aplenty in Antarctica

Guano mining became a profitable business, and a grim one.

ECONOMIST: The story of man's staple food

In the new study, scientists first located the emperor-penguin breeding colonies by scanning satellite images for telltale patches of reddish-brown penguin guano on the ice, which are readily spotted from space.

WSJ: Emperor Penguins Aplenty in Antarctica

In about 1830 a magic ingredient was found: guano.

ECONOMIST: The story of wheat: Ears of plenty | The

Off South-West Africa, the discovery in 1843 of the tiny island of Ichaboe, covered in 25 feet of penguin and gannet excrement, led to a guano rush followed by a mutiny and battles.

ECONOMIST: The story of wheat: Ears of plenty | The