How Bird Guano Changed the History of Kuaihelani

By Bill Levin

Kuaihelani is a sacred place and its name means the “Backbone of Heaven.” However, Native Hawaiians and ancient mariners have a local or common name for Kuaihelani which is “Pihemanu,” meaning “loud din of birds” for the millions of seabirds occupying this remote atoll in the Northwestern Hawaiian Islands. Because of these “riches,” Kuaihelani, also known as Midway Atoll, became of strategic importance to the United States for bird poop. Yes, you read that right. The “Guano Islands Act of 1856” led directly to Midway Atoll becoming a territory of the United States in 1859.

Cover page of 1856 Guano Islands Act. Courtesy of National Archives and Records Administration.

The Act’s sponsor in the U.S. Senate was the very same William Henry Seward who later spearheaded the purchase of Alaska by the United States.

Bird poop was the source of agricultural fertilizer. Fifty years before Seward’s legislation, Alexander von Humboldt had brought bird poop all the way from Peru to a Prussian chemist, who in turn found that it contained high concentrations of nitrogen and phosphorus, offering farmers of Europe a strategic solution to the age-old problem of soil exhaustion. [1]

Hand-colored wood engraving from 1894 depicting guano being collected on one of Peru’s three Chincha islands in the mid-1870s. By this time, very little guano was left on the islands. Courtesy of Corbis

A 19th-century illustration depicts a scene off the coast of Peru, where bird poop, or guano, was harvested as a valuable agricultural fertilizer. Courtesy of Corbis

In the century until the Haber-Bosch process was developed to take nitrogen from the air and convert it to ammonia, and synthetic fertilizers became available [2], guano was highly prized. Thus, Midway Atoll became an important asset for the United States for the first (but not the last) time.

The “USS St. Mary's” protected guano island claims by American citizens and collected guano samples while patrolling the Pacific Ocean. Courtesy of Naval History and Heritage Command, Photo Archive.

Midway Atoll was not the official United States name until annexation in 1867, but the atoll was reported and claimed as an unincorporated United States Territory by Captain N. C. Brooks of the U. S. Navy in 1859 under the Act passed three years earlier. Later generations found strategic importance at Midway including in 1903, when President Theodore Roosevelt placed the U.S. Navy in control of Midway and the same year the island became a station for the first Transpacific telegraph cable. A little more than thirty years later, the PanAmerican clippers traveling from San Francisco to the Pacific stopped at Midway, and not many years before the hostilities of World War II, the Navy significantly upgraded its presence.[3] Nearly the entire reach of Papahānaumokuākea Marine National Monument is built historically upon the Guano Islands Act of 1856 and the need of an expanding U.S. government to feed its population through agricultural improvement.

Midway Atoll as seen from a helicopter — Kuaihelani (Midway Atoll) as seen from a helicopter by Jon Brack 2023

Today, the significance of Kuaihelani significance endures—not as a strategic outpost, but as one of the world’s most important refuges for seabirds, marine life, and cultural history, reminding us that its past continues to shape its purpose in the present.

[1]Kolbert, “Phosphorus Save Our Way Of Life and Now Threatens to End It.” The New Yorker, March 6, 2023.

[2]Flavell-While, “Fritz Haber and Carl Bosch–Feed The World.” The Chemical Engineer, March 1, 2010.

[3] “Midway Islands, United States Territory, Pacific Ocean.” Britannica AI, March 11, 2026.

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