Guano Islands Act: How Seabird Poop Won WW2

There’s a buried nugget from the United States’ own colonialist era that has to do with claiming new territory. Specifically, the the Guano Islands Act of 1856 has to do with bird poop. The first section reads:

“Whenever any citizen of the United States discovers a deposit of guano on any island, rock, or key, not within the lawful jurisdiction of any other government, and not occupied by the citizens of any other government, and takes peaceable possession thereof, and occupies the same, such island, rock, or key may, at the discretion of the President, be considered as appertaining to the United States.”

Got that? If you find yourself on an unclaimed island, or even just a rock, in the middle of the ocean and a bird has pooped on it, you can claim that land for the United States of America.

Cool, huh? And…disgusting, but certainly such a ridiculous act can’t have had any real effect on the world, right?

Let’s go into why guano, or seabird poop, was so valued in the 1800s. Saltpeter is the chemical compound sodium nitrate. It forms the basis for both gunpowder and many fertilizers. In fact, it was so valuable in terms of militarizing (and feeding) a country that a war was even fought between Bolivia and Peru from 1879 to 1883. Mineral deposits of saltpeter had been claimed in the Atacama Desert by both countries.

Aside from mineral deposits, where else can saltpeter be found in large amounts? Seabird poop. “Guano mania” had struck the U.S. in the 1850s, and companies scrambled to strip-mine islands for their contents. Congress passed the Guano Islands Act both to encourage pioneers to seek out new deposits on islands and reefs, while also justifying military intervention in maintaining them.

This also began the U.S. practice of establishing insular territory – land that could be occupied by the federal government with no intention or possibility of one day becoming a state. It also meant that, as soon as the islands’ resources had been stripped, the United States could cease occupation and any responsibility therein.

Pretty nice of us, huh?

The most important contribution of the Guano Islands Act may have been the securing of the Midway Atoll in 1859. (An atoll is a lagoon sectioned off from the ocean by a rim of coral reef that breaks the surface of the sea as land.) This was the first Pacific island annexed by the United States. The island of Midway, within the atoll, became a crucial refueling depot for Navy ships. As tensions rose between the United States and Japan in 1940, the island of Midway was fortified with air fields and a seaplane base.

The Japanese attacked Pearl Harbor on December 7, 1941, crippling the base, sinking 12 ships (including four battleships), destroying 188 aircraft, and killing 2,403. Midway was the next most important base in the Pacific.

With the battleships of its Pacific Fleet either destroyed or damaged, when the Japanese attacked Midway on June 4, 1942, the United States Navy had to rely on brand new strategies centered around aircraft carriers. Three American carriers took on 4 Japanese carriers, sinking them all in what most historians view as the turning point in the Pacific War. All because Congress valued seabird poop.

Today, Midway is a wildlife refuge, and home to three million nesting seabirds. This includes 70 percent of the world population of Laysan albatross and 39 percent of the world population of black-footed albatross. Debris washed ashore from both North America and Eastern Asia has become the island’s most pressing problem, killing many birds, sea turtles, dolphins and other native life.


Have you ever heard of the Guano Islands Act? What strange piece of history do you know that’s changed the course of nations?




Gabriel Valdez
Gabriel Valdez
Gabriel is a movie critic who's been a campaign manager in Oregon, an investigative reporter in Texas, and a film producer in Massachusetts. His writing was named best North American criticism of 2014 by the Local Media Association. He's assembled a band of writers who focus on social issues in film. They have a home base.