The United States has over 50 islands that were once claimed for their guano deposits. Guano is the accumulated excrement of seabirds, bats, or seals and has long been a highly effective fertilizer. In the 19th century, guano was a prized commodity and the islands where seabirds nested were seen as valuable real estate. The United States passed the Guano Islands Act in 1856, which allowed US citizens to claim islands with guano deposits in the name of the US government. This led to a “guano rush” as US entrepreneurs raced to claim guano-rich islands across the Pacific and Caribbean.
The Guano Islands Act of 1856
The Guano Islands Act was passed by Congress in 1856 and enabled US citizens to take possession of unclaimed islands containing guano deposits in the name of the United States. The islands could then be mined for guano, which was sold back in the United States to be used as fertilizer. At the time, guano was a highly sought-after commodity because of its superior quality as a natural fertilizer. The Guano Islands Act essentially turned guano into a vital US strategic resource.
Any US citizen could claim an uninhabited island with guano deposits simply by filing a claim and placing a marker on the island. Over the next few decades, nearly 100 guano islands were claimed in the Pacific and Caribbean under the Guano Islands Act. While the act helped the US gain access to valuable guano resources, it also led to territorial disputes with other nations who had their own claims on some of the islands.
Key US guano islands in the Pacific
Some of the key guano islands claimed by the US in the Pacific included:
- Navassa Island – a small Caribbean island off the coast of Haiti that was rich in guano deposits. Claimed under the Guano Islands Act in 1857.
- Jarvis Island – a remote coral island near the equator in the South Pacific. Claimed under the Guano Islands Act in 1858.
- Baker Island – part of the Phoenix Islands in the South Pacific with substantial guano deposits. Claimed in 1857.
- Howland Island – near Baker Island, claimed under the Guano Islands Act in 1857.
- Johnston Atoll – claimed in 1858 and mined extensively for guano in the 1870s and 1880s.
Of these islands, Navassa Island held the richest guano deposits. Mining of guano on Navassa Island lasted up until 1898. Over 5 million tons of guano was ultimately removed from Navassa Island in the 19th century.
Key US guano islands in the Caribbean
In addition to the remote Pacific islands, the US also claimed a number of Caribbean islands for their guano resources including:
- Swan Islands – small islands off the coast of Honduras, claimed in 1860.
- Aves Island – a Venezuelan island with substantial guano deposits, claimed by the US in 1854 before Venezuela disputed it.
- Serrana Bank – near Colombia’s San Andrés Island, claimed by both the US and Colombia.
- Roncador Bank – also near San Andrés Island and disputed with Colombia.
- Serranilla Bank – south of Jamaica, claimed by the US but later determined to belong to Colombia.
- Quita Sueño Bank – near Jamaica, claimed for the US in 1869 before being disputed by Colombia.
The small Caribbean guano islands were unable to match the huge volumes of guano exported from the Pacific islands. Still, they contributed to the critical guano trade that spread this valuable fertilizer across the United States.
The legacy of the Guano Islands Act
While the Guano Rush ended by the late 19th century as guano deposits were exhausted, the Guano Islands Act left a lasting legacy for US territorial claims. Many of the remote Pacific islands claimed for guano remained US possessions and eventually evolved into strategic military bases and atolls.
Here is how some of the key guano islands ended up:
- Navassa Island – still a US territory but largely abandoned now.
- Jarvis Island – part of the Pacific Remote Islands Marine National Monument, protected for wildlife.
- Baker Island – also part of the marine national monument.
- Howland Island – transferred to the US Air Force in 1937. Played a storied role during Amelia Earhart’s disappeared flight around the world.
- Johnston Atoll – used by the US military as a nuclear testing site in the 1950s and 60s before becoming a bird sanctuary.
In total, there are still over 50 islands across the Pacific and Caribbean that were originally claimed for the US under the Guano Islands Act in the 19th century. While no longer used for guano extraction, many of these islands remain US territories and play strategic roles.
The Guano Rush may be a largely forgotten part of American history, but it helped spur US territorial expansion across the oceans at a key time in the country’s growth. And it was all done in the name of bird poop.
Conclusion
The United States claimed over 50 islands for their guano deposits in the 19th century, though the Guano Rush was relatively short-lived. In the Pacific, remote islands like Navassa, Jarvis, Baker, Howland, and Johnston Atoll were rich sources of guano fertilizer before the deposits were exhausted. In the Caribbean, smaller islands were claimed as well, though they could not match the volumes of the Pacific. While the Guano Rush faded, it left the US with territorial holdings across the oceans that became strategically important over time. So while mining guano was the initial impetus, the enduring legacy was the expansion of American territorial reach using the Guano Islands Act of 1856.