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When the World Ran on Bird Shit
They called it the “Great Heap.” It towered above the surface of one of the Chincha Islands off the coast of Peru. Take a look at these photos from 1865:

At first glance, it looks kind of like a mountain. A little bit like Uluru/Ayers Rock in Australia, perhaps. But this towering structure, a couple of hundred feet high, was not a mountain of rock.
It was a mountain of bird shit, two million tons of it. This mountain of shit saved lives, sparked war, made people immensely rich, and served as an unexpected engine of world history.
Let’s start at the beginning. Why was there a mountain of shit on this island?
Off of the west coast of South America, there are a number of little islands, including the three that make up the Chincha archipelago, where the above pictures were taken. They have, since time immemorial, been a nesting site for seabirds. Tens of millions of them, in fact. To give you a sense of the numbers, the photo below, taken in 1910 for a U.S. government report, is drily captioned, “Very small portion of a flock of cormorants on the south island of the Chinchas.”
These birds feed on the fish that swim up the coast and nest in massive colonies on these islands. There they poop, and poop some more.
There are lots of places with large bird populations, but what makes the Chinchas unique is that they are also some of the driest places on Earth. A 1910 article put it this way: “Aged men [from the Chincha Islands] can count on the fingers of one hand the times in their lives when they have seen this marvelous thing — water falling from the skies.”
Without rain to wash it away, pure, unadulterated guano accumulated on the islands for centuries in deposits a hundred feet high or more.
Local people had been aware of the islands, and used the guano on them, for centuries. At least as far back as the Inca period, people had settled the islands and exported guano from them. But it wasn’t until the 1800s that these islands became the subject of intense international interest.
Peruvian guano became world famous for a few reasons. First, the illustrious, endlessly curious German scientist Alexander von Humboldt traveled to Peru in the early 1800s and got his hands on some. He brought it back to Europe, had it tested, and found that it was packed with nitrogen and phosphorous — the two most important ingredients for making plants grow. This wasn’t surprising, really —most agricultural fertilizer had always been manure from both animals and humans.
But Peruvian guano was incredibly concentrated and pure. It was rocket fuel for plants.
The guano came to Europeans’ attention at precisely the right time. The early 1800s were a period of huge demographic change. Thomas Malthus famously noted around the turn of the nineteenth century that population in Europe was increasing exponentially, while the food supply was increasing arithmetically. Since the population was growing much more quickly than the food supply, it was only a matter of time until a terrible famine killed millions and brought populations down to their “natural
level.”

Farmers needed a way to produce more food. Guano would provide it.
Savvy businessmen descended on the guano islands, many of them associated with the whaling ships that were already hunting in the seas nearby. They developed a huge industry, essentially overnight.
Extracting the fertilizer from guano mountains and transporting it to the farms of the world was a monumental task. The guano had to be mined, as if it was a mineral.
You can see the scale of the operations in some of the photos below. Workers scaled the guano mountains and hacked out the fertilizer:

The guano was loaded into carts and transported to the docks:
The carts were tipped into chutes that ran down to the holds of boats, which would transport the guano to larger ships and then to the rest of the world:
You can get a sense of the size of the trade from the number of boats that are lined up in this drawing from 1863:
The guano islands were awful places, where some of the worst aspects of the nineteenth century — slavery, imperialism, and war — came to roost.
As you might imagine, hacking away at bird shit and then transporting it long distances was a terrible job. These were harsh islands, many of them just rocks sticking out of the Pacific. There weren’t good places to live, and there was often no fresh water. The guano itself was disgusting; crewmen on the ships transporting it had to limit their time down in the hold because the stench caused nosebleeds.
Needless to say, this was not a desirable job. So who are the workers in those photos above?
Many of the people working on the islands were not entirely free. Tens of thousands of them were indentured Chinese people, many of whom had been manipulated into being there. They’d been lied to about their destination and the work they’d be doing, or been tricked into debts that could only be repaid with work in the guano mines. Other workers had been kidnapped from Pacific islands and forced into virtual slavery.
Though the Chincha Islands in Peru were the origin of the guano gold rush, businessmen began to look for other deposits of bird shit. It turned out that there were lots of little islands in oceans around the world (for example, there was another set of dry islands full of birds off of Namibia), and many of them had never been formally claimed by a country.
The United States, at the peak of its Manifest Destiny era, passed a law showing that it considered guano to be an important national security asset. The Guano Islands Act in 1856 told American citizens that they could take possession of any unclaimed island that possessed guano deposits. The U.S. government promised to back up all of those claims with its military might.
The U.S. wasn’t the only country claiming territory for itself. Spain, in a misguided attempt to reassert some of its influence over South America, began throwing its weight around in the 1860s by sailing naval squadrons up the Pacific coast of the continent and pressing the claims of Spanish citizens to land and property there. When Peru resisted the pressure, the Spanish seized its most valuable asset — the Chincha Islands. Here we see Spanish sailors occupying one of the islands:
It worked — Peru, deprived of its guano income, quickly capitulated. Though the conflict over the Chinchas was over by 1865, the Chincha Islands War continued for more than a decade, eventually pitting several South American nations against Spain.
The guano trade was big business. Advertisements for bird poop ran all over the world, and farmers went crazy for the stuff.
The Pacific Guano Company even built a pavilion at the 1876 World’s Fair:
But by this point, the guano industry was in decline.
The guano gold rush was intense, but brief. The Journal of Geography stated in 1910 that “It is doubtful that there be another spot of equal size on the earth’s surface from which so much wealth has been taken as from the guano beds on the Chincha Islands.” The guano deposits there had helped to fuel an economic and population boom, but they were largely gone by the 1870s.
As with so many unsustainable businesses, the guano islands were exploited, depleted, and then forgotten. They were left to to the birds once more. Farmers looked for other ways to feed their crops. Eventually, artificial fertilizer — produced with the energy-intensive Haber-Bosch method — took the place of bird shit in fields around the world.
But the guano era had been an important one. Thomas Malthus turned out to be wrong — there was no widespread famine in the nineteenth century. But he was wrong partially because he hadn’t anticipated the discovery of mountains of bird shit on faraway islands.
For three crucial decades, these remote fecal deposits fed much of the world. They were the disgusting fuel behind the western world’s population and economic boom.