Henderson Island

• Official name: Henderson Island
• Location: Pitcairn Islands
• Type: Natural
• Year of inscription: 1988

Henderson Island is an uninhabited island in the south Pacific Ocean that forms part of the Pitcairn Island Group. Previously known as San Juan Bautista and Elizabeth Island, Henderson Island and the rest of the Pitcairn Islands are a British Overseas Territory. One of only two raised coral atolls remaining in the world, Henderson Island is a unique natural wonder. Given its extremely isolated location and inhospitable terrain, the island’s ecology is relatively unaffected by human contact and, therefore, ideal for studying insular evolution and natural selection. For these and other reasons, Henderson Island was named a United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Site list in 1988.

Henderson Island is located about 120 miles (193 kilometers) northeast of Pitcairn Island in the Pacific Ocean. It measures approximately 6 miles (9.7 kilometers) by 3.2 miles (5.1 kilometers) and has an area of roughly 14.4 square miles (37 square kilometers). This makes it the largest of the four islands in the Pitcairn Islands Group. Henderson Island is known for its poor soil and limited supply of fresh water, conditions that make it unsuitable for agriculture. The northern end of the island features three beaches. The rest of its coastline is marked by steep cliffs stretching as high as 50 feet (15 meters) above sea level.

Despite its small size, Henderson Island boasts a remarkable degree of biodiversity. The island is home to a wide variety of plant and animal species. In addition, a significant number of its flowering plants, insects, and gastropods—as well as all four of its existing land bird species—are endemic, meaning that they do not exist anywhere else in the world. However, Henderson Island faces at least two significant ecological risks. The first is its large population of invasive and predatory Pacific rats, which threatens the survival of other species. The second is plastic pollution resulting from waste that washes up on the island because of the South Pacific Gyre.

History

Although conditions on Henderson Island are not conducive to supporting human habitation, archeologists have unearthed evidence that a small permanent Polynesian settlement once existed on the island. Based on these findings, experts estimate that Polynesians likely lived on the island sometime between the twelfth and fifteenth centuries, though they may have arrived as early as the ninth century. At some point, these inhabitants left Henderson Island for reasons that remain unknown. Since that time, no permanent human residents have lived on the island.

In January 1606, Pedro Fernandes de Queirós became the first European to lay eyes on Henderson Island. A Portuguese captain then leading a Spanish expedition, Queirós named the island San Juan Bautista. Two centuries later, in 1819, the British East India Company’s Captain James Henderson rediscovered the island while passing by in a ship called Hercules on a voyage to India. Just six weeks after Henderson’s sighting, Captain Henry King of the Elizabeth landed on the island. Some members of King’s crew scratched the name of their ship into a tree there. As a result, the island was alternately referred to as either Henderson’s Island or Elizabeth. Ultimately, the name Henderson Island stuck.

On November 20, 1820, the Nantucket whaleship Essex was rammed and sunk by a sperm whale in the region. Several surviving crew members landed on Henderson Island a month later and located a brackish spring on the north shore that turned out to be the island’s only source of consumable water. The full party of shipwrecked survivors subsisted on fish, birds, eggs, crabs, and peppergrass for a week before effectively exhausting the island’s meager food supply. All but three of the survivors left Henderson Island on December 27 in hopes of reaching South America. The men who stayed behind—Thomas Chappel, Seth Weeks, and William Wright—managed to survive until they were rescued on April 9, 1821. The story of the Essex is said to have inspired author Herman Melville to write Moby Dick.

While visiting Henderson Island in 1851, some travelers from Pitcairn Island discovered human remains in a cave adjacent to a wreckage-strewn beach. Just over a century later, another group of people from Pitcairn Island rediscovered these remains. Medical examiners initially came to believe that the remains were the bones of several individuals of European descent buried in a shallow grave within the cave. In 1966, the remains were reexamined by an American survey team. They determined that the grave contained the remains of three to five people, one of whom was a young child. The survey team surmised that the victims were shipwreck survivors who ultimately died of dehydration. One further examination in 1991 revealed that the remains belonged to prehistoric Polynesians.

Henderson Island, Oeno Island, and Ducie Island were all annexed to the British Empire by Captain G. F. Jones in 1902. During an aerial survey conducted in 1937, a British flag was planted on each island with a plaque establishing the official claim of George VI. All three have been part of a British Overseas Territory ever since.

In 1957, an American named Robert Tomarchin lived on Henderson Island for about two months as a castaway. Accompanied by a pet chimpanzee, Tomarchin supposedly traveled to the island as a publicity stunt. He was eventually rescued by a group of individuals from Pitcairn Island.

American business magnate Arthur “Smiley” Ratliff attempted to purchase Henderson Island from the British government in the early 1980s. He sought to build a mansion with an airstrip on the island, but the British Foreign and Commonwealth eventually declined Ratliff’s offer thanks to objections from environmentalists.

In 1988, Henderson Island was officially listed as a UNESCO World Heritage Site. A scientific study undertaken in 2017 subsequently revealed that Henderson Island’s beaches contained an estimated 37.7 million items of plastic debris that washed ashore because of the South Pacific Gyre, a rotating ocean current that is heavily polluted with plastic. This meant that the island’s beaches had the highest density of plastic waste of any known location worldwide.

Significance

Henderson Island is listed as a UNESCO World Heritage Site because it is one of the world’s best preserved and last surviving raised coral atoll ecosystems. A raised coral atoll is unique from other atolls in that it is elevated far enough above sea level by tectonic forces to be protected from scouring by storms. This allows its soil and lifeforms to develop and thrive. Because of its remote location, Henderson Island is one of only two tropical raised atolls of note in the world left largely unaltered by human activity. The other is Aldabra Island in the Indian Ocean, which is also a UNESCO World Heritage Site.

Locales under consideration to become UNESCO World Heritage Sites must meet at least one of ten established selection criteria. Henderson Island met two of those criteria, VII and X. While criterion VII states that a proposed site must “contain superlative natural phenomena or areas of exceptional natural beauty and aesthetic importance,” criterion X states that a site must “contain the most important and significant natural habitats for in-situ conservation of biological diversity, including those containing threatened species of outstanding universal value from the point of view of science or conservation.” Henderson Island meets criterion VII because it is counted among the last remaining near-pristine limestone islands of its size in the world. Further, because of its remote location, its natural beauty is intact and undisturbed. It is marked by white sand beaches, limestone cliffs, and vast vegetation. In addition, the features of the island’s raised coral atoll are largely intact and preserved. It also serves as a sanctuary for many breeding seabirds. Henderson Island meets criterion X for several reasons. Most importantly, the island is home to four endemic species of land birds, one of which is the flightless Henderson crake. It is an important breeding site for multiple seabird species. One of these is the endangered Henderson petrel, which is believed to breed exclusively on the island. Henderson Island is also unique in that it is home to a much larger number of plant species than most other islands of its kind. These include six endemic species, three endemic varieties, and one species endemic to both Henderson and Pitcairn. Scientists believe that Henderson Island could also be home to other endemic plant species that have not yet been discovered.

Henderson Island also meets UNESCO’s conditions for integrity. Aside from the early Polynesian colonies that existed for a time, humans have never permanently inhabited the island. This is in large part because its remote location, inaccessibility, and inhospitable conditions make human habitation a virtual impossibility. As a result, Henderson’s natural ecosystem is remarkably well-preserved. In addition, the island’s ecological integrity has only two significant threats: invasive rats and plastic pollution. Henderson Island is heavily populated by Polynesian rats, an invasive species introduced many centuries ago that preys on the island’s native birds to the extent that extinction of species may occur. Henderson Island is also subjected to a significant degree of plastic pollution because of a large amount of waste that washes ashore because of the South Pacific Gyre. This plastic problem continued into the twenty-first century, and by the mid-2020s, it was believed the island contained over 38 million pieces of plastic. Plastic pollution was a persistent and severe problem affecting the island’s wildlife and ecosystems. The unique geography and location of Henderson Island complicated clean-up efforts. However, in 2024, nine tons of plastic were removed from the island.

Bibliography

“Henderson Expedition: The World’s Most Polluted Protected Island Gets Rid of 9 Tons of Plastic Waste.” Plastic Odyssey, 13 Mar. 2024, plasticodyssey.org/en/2024-henderson-island-expedition-completed. Accessed 2 Dec. 2024.

“Henderson Island.” Pacific Union College Pitcairn Islands Study Center, library.puc.edu/pitcairn/pitcairn/henderson.shtml. Accessed 2 Dec. 2024.

“Henderson Island.” UNESCO World Heritage Centre, whc.unesco.org/en/list/487. Accessed 2 Dec. 2024.

“Henderson Island.” World Heritage Datasheet, June 2011, world-heritage-datasheets.unep-wcmc.org/datasheet/output/site/henderson-island. Accessed 2 Dec. 2024.

“The Henderson Island Skeletons.” Pacific Union College Pitcairn Islands Study Center, library.puc.edu/pitcairn/pitcairn/skeletons.shtml. Accessed 2 Dec. 2024.

Uibu, Katri. “Researchers Collect Tonnes of Plastic from Henderson Island, but Leave It all Behind.” ABC, 3 July 2019, www.abc.net.au/news/2019-07-04/plastic-rubbish-henderson-island-researchers-tasmania/11276012. Accessed 2 Dec. 2024.

Vance, Andrea and Iain McGregor. “Henderson Island: The Pacific Paradise Groaning Under 18 Tonnes of Plastic Waste.” Guardian, 29 July 2019, www.theguardian.com/environment/2019/jul/30/henderson-island-the-pacific-paradise-groaning-under-18-tonnes-of-plastic-waste. Accessed 2 Dec. 2024.

Yong, Ed. “A Remote Paradise Island Is Now a Plastic Junkyard.” The Atlantic, 15 May 2017, www.theatlantic.com/science/archive/2017/05/a-remote-paradise-island-is-now-a-plastic-junkyard/526743. Accessed 2 Dec. 2024.