Guano: The White Gold of the Seabirds

by Ken Rock, MSDC Editor

Guanay cormorants, top-notch guano producers, hanging out in Peru. Photo by An en Alain, Flicker. 

Imagine a natural resource that, after discovery, is found to be so efficient and powerful that it revolutionizes an entire industry. Deposit-holding countries, businessmen, and speculators get rich. Laborers remove it from the ground, and ships carry it around the world, where it helps to power everyday life. Thanks to the social habits of the birds that produce it, it tends to be available in huge, concentrated, perpetually regenerating heaps.

For the second half of the 19th century, much of the Western world relied on such a resource, a super-powerful substance called guano, or  bird poop. Made almost entirely of nitrogen, phosphate and potassium, it served as an amazing fertilizer that provided straight-up energy for plants.

When its powers became known, demand quickly outstripped supply and world powers fought for the remaining supplies. Unprecedented legislation was passed, questionable diplomatic decisions were made, and power struggles among countries ensued.  

The term “Guano” applies to natural mineral deposits consisting of excrements, eggshells and carcasses of dead seabirds found in almost rainless, hot-dry climatic regions. The word Guano derives from the Peruvian original language Quechua; of “Huano,” which means “dung to fertilize."

Before Europeans “discovered” guano, the Inca took advantage of these properties for hundreds of years. Inca kings were well aware of the benefits guano would have on crops and imposed strict rules for mining that basically took the resource out of the hands of private sector "guano lords," and ensured a sustainable harvest.

Densely packed Guanay Cormorants on the Chincha Islands, 1907. Photo by the U.S. National Museum (now the Smithsonian). Images is from Coker, “Habits and Economic Relations of the Guano Birds of Peru,” 1920.

The Beginning of the Guano Boom

For centuries, European explorers and colonizers, blinded by shinier commodities, did not bother to look into guano. The first to do so was the Prussian naturalist, geographer, and explorer Alexander von Humboldt, who could not ignore it. Humboldt had traveled to Peru for research and noticed the constant shipments of the ammonia-rich guano which made him sneeze. When Humboldt returned to Europe in 1804, he brought back some samples and turned them over to “the best analytical chemists of the day."

The Guanay comorant has historically been the most important producer of guano.Photo by Quartl,

The chemists immediately recognized that they were dealing with powerful stuff. Farmers in Europe and in the U.S. were beginning to worry about their depleted soil’s ability to feed a growing population. Although many different types of fertilizers were tried, none were as chemically promising as guano, which is full not only of nitrogen, but also is packed with phosphate and potassium.

The nest of the Peruvian booby is made of almost pure guano. Taken at La Vieja Island, Paracas National Reserve, Departamento Ica, Peru. Photo by Wikipedia.

The Guano Trade

Thus began the guano trade – on three tiny Peruvian islands in the Pacific – and their product ultimately reached farmers’ fields around the world.

The three tiny Chincha Islands lie off the southern coast of Peru. For millennia, they served as home for seabirds. The birds fed and bred in the rich waters packed with fish and absent of predators, allowing their droppings to accumulate to a depth of up to 200 feet. The dry weather and cool ocean currents there maintained the guano’s nitrate-rich quality.  

Extracting the Chincha Islands Guano. The vertical channels were cut into the surface of “The Great Heap” of seabird guano by miners pickaxing the solidified droppings from the mound. Photo from Gardner, Rays of Sunlight from South America, 1865.
Chinese guano miners, 1865. The remarkable height of the deposit is shown by the figures of the indentured Chinese miners. After South American prisoners and slaves and Hawaiian workers were no longer available, as many as 90,000 Chinese men were brought in to work the Chincha deposits. Photo from Gardner, Rays of Sunlight from South America, 1865.

In the early 19th century, farmers and chemists worldwide claimed that Chincha Islands guano was the world’s finest fertilizer. Hundreds of British, German, and American ships purchased it from the Peruvian government for their own agriculture, waiting offshore up to eight months to load the precious cargo.

Once the guano was pickaxed from the ground, it was shoveled into carts on rails and transported to the edge of the steep cliffs for transfer to the boats below. Photo from Gardner, Rays of Sunlight from South America, 1865.

These nations’ ships also sought, claimed, and mined other guano islands in the Pacific and Caribbean. Although they recognized the practices weren’t sustainable, they continued to harvest the guano. By the late 1870s, nearly all of the Chincha Islands guano was gone, and the seabird habitat was ruined by the mining operations.

Wheelbarrows of guano were dumped into wooden chutes at the top of the cliff, from which it slid down into lighters (small craft). The cliffs were too steep for the large ships to approach safely, so the lighters transported the loose guano out to the vessels anchored offshore. Photo from Corbis, 1857.

In the heyday of the guano trade, up to 300 ships per year visited the Chincha Islands and waited offshore to load. When the loading started, all inside doors and windows were closed and tightly covered with canvas to prevent the toxic dust from filling a ship’s crew spaces. Loading crews were limited to 20-minute shifts in the cargo holds and the rest of the crew climbed to the tops of the masts to breathe fresh air.

The clipper ship "Black Warrior" was built in Maine in 1853 and purchased by a Baltimore shipping company. It made guano voyages to Peru in 1855 and 1857. It also sailed to China twice in the late 1850s. Gift of CIGNA Museum and Art Collection.
The clipper ship "Black Warrior" was built in Maine in 1853 and purchased by a Baltimore shipping company. It made guano voyages to Peru in 1855 and 1857. It also sailed to China twice in the late 1850s. Gift of CIGNA Museum and Art Collection.

The Guano Islands Act of 1856

By the 1840s, the remarkable properties of Peruvian seabird guano were widely recognized, as farmers claimed that using the fertilizer increased their crop yields up to three times. American farmers demanded the nitrate-rich fertilizer from Congress to restore their worn-out fields’ soil balance and increase production.

For the sake of seabird droppings, a powerful fertilizer, the U.S. Congress authorized our nation’s earliest significant expansion beyond the continent.

In his 1850 State of the Union address, President Millard Fillmore said that guano from Peru was so valuable that the U.S. government should "employ all the means properly in its power" to get it.

The resulting Guano Islands Act stated that the U.S. could claim any island that had seabird guano on it, so long as there were no other claims or inhabitants. Any guano mined had to be sold to American farmers as fertilizer at a reasonable price. Guano was at the time the finest natural fertilizer and farmers needed it to replenish the nutrients in their fields and increase their crop yield. This act authorized our nation’s earliest significant annexations of lands beyond the continent.

Around 200 guano islands were claimed by Americans in the 19th and early 20th centuries. Nine remain today as unincorporated territories. Some of them are pretty well known: Howland Island, where Amelia Earhart was supposed to land; Midway Atoll, a strategic key to America's defeat of Japan in World War II, and Johnston Atoll, a little speck of coral in the Pacific so remote that the U.S. tested nuclear and chemical weapons there before abandoning it a few years ago.

Facsimile of original 1856 Guano Islands Act. Photo Courtesy of National Archives and Records Administration.

Sources include:

1) The Guano Trade, Smithsonian National Museum of American History

2) The Smithsonian and the 19th century guano trade: This poop is crap, Smithsonian National Museum of American History, by Paul F. Johnston, May 31, 2017

3) Wikipedia, Alexander von Humboldt