Pitcairn, Henderson, Ducie and Oeno Islands

The Pitcairn Islands are a group of four volcanic islands in the southern Pacific Ocean that form the sole British Overseas Territory in the Pacific Ocean. The four islands are Pitcairn, Henderson, Ducie and Oeno. They are scattered across several hundred kilometres of ocean and have a combined land area of about 47 km2 (18 square miles). Henderson Island accounts for 86% of the land area, but only Pitcairn Island is inhabited. The inhabited islands nearest to the Pitcairn Islands are Mangareva (of French Polynesia), 688 km to the west and Easter Island, 1,929 km to the east. The Pitcairn Islanders are a biracial ethnic group descended mostly from nine HMS Bounty mutineers and a handful of Tahitian consorts. As of 2023, the territory had only 35 permanent inhabitants.

The Pitcairn Islands form the southeasternmost extension of the geological archipelago of the Tuamotus of French Polynesia, and consist of four islands: Pitcairn Island, Oeno Island (atoll with five islets, one of which is Sandy Island), Henderson Island and Ducie Island (atoll with four islets). They were formed by a centre of upwelling magma called the Pitcairn hotspot. Pitcairn Island is a volcanic remnant where the north side of the cone has been eroded. Pitcairn is the only permanently inhabited island. Adamstown, the main settlement on the island, lies within the volcanic basin.

Bounty Bay – ©Henning Axt CC BY-SA 3.0 via Wikimedia Commons

It is accessible only by boat through Bounty Bay, due to the island’s steep cliffs. Henderson Island supports a rich variety of animals in its nearly inaccessible interior, is also capable of supporting a small human population despite its scarce fresh water, but access is difficult, owing to its outer shores being steep limestone cliffs covered by sharp coral. It is designated as a UNESCO World Heritage site. The other islands are at a distance of more than 100 km (62 miles) and are not habitable. Pitcairn Island has no permanent water source; however, the island has three seasonal semi-permanent springs. Pitcairn is located just south of the Tropic of Capricorn and experiences year-round warm weather.

The islands are best known for being the home of the descendants of the HMS Bounty mutineers and the Tahitians who accompanied them, an event retold in numerous books and films. This story is still apparent in the surnames of many of the islanders. It is also notable for being the least populated jurisdiction in the world (although it is not a sovereign nation). The United Nations Committee on Decolonisation includes the Pitcairn Islands on the United Nations list of Non-Self-Governing Territories.

Adamstown – ©Makemake CC BY-SA 3.0 via Wikimedia Commons

Pitcairn Island is remarkably productive and its benign climate supports a wide range of tropical and temperate crops. Isaac’s Valley on the gentle slopes southeast of Adamstown, produces a wide variety of fruits, including bananas, papaya (paw paws), pineapples, mangoes, watermelons, cantaloupes, passionfruit, breadfruit, coconuts, avocados, and citrus (including mandarin oranges, grapefruit, lemons and limes). Vegetables include sweet potatoes (kumura), carrots, sweet corn, tomatoes, taro, yams, peas, and beans. Arrowroot and sugarcane are grown and harvested to produce arrowroot flour and molasses, respectively. An apiculture programme was undertaken for Pitcairn including training for Pitcairn’s beekeepers and a detailed analysis of Pitcairn’s bees and honey with particular regard to the presence or absence of disease. Pitcairn has one of the best examples of disease-free bee populations anywhere in the world and the honey produced was and remains exceptionally high in quality. Fish are plentiful in the seas around Pitcairn. Spiny lobster and a large variety of fish are caught for meals and for trading aboard passing ships.

About nine plant species are thought to be endemic to Pitcairn. These include tapau, formerly an important timber resource, and the giant nehe fern. Some, such as red berry Coprosma rapensis var. Benefica, are perilously close to extinction. The plant species Glochidion pitcairnense is endemic to Pitcairn and Henderson Islands.

Pitcairn is part of the Tuamotu tropical moist forests terrestrial ecoregion.

Birding The Pitcairns

The British government established one of the largest marine protected areas in the world around the Pitcairn Islands. The reserve covers the islands’ entire exclusive economic zone of 834,334 km2  (322,138 square miles). The intention is to protect some of the world’s most pristine ocean habitat from illegal fishing activities. A satellite ‘watchroom’ dubbed ‘Project Eyes on the Seas’ has been established by the Satellite Applications Catapult and the Pew Charitable Trusts at the Harwell Science and Innovation Campus in Harwell, Oxfordshire to monitor vessel activity and to gather the information needed to prosecute unauthorised trawling. Recently, the International Dark-Sky Association approved the Pitcairn Islands as a Dark Sky Sanctuary. The sanctuary encompasses all 4 islands in the Pitcairn Islands Group.

A small population of humpback whales migrate to the islands annually, to over-winter and breed.

Henderson Island – ©Ron Van Oers CC BY-SA 3.0 IGO via Wikimedia Commons

Just sixty-five species of bird have ever been recorded in the island group, but no less than five are endemic and one wide-wandering seabird breeds nowhere else. The birds of Pitcairn fall into several groups. These include mostly seabirds, and wading birds but there are a handful of resident land-bird species. Of 20 breeding species, Henderson Island has 16, including the unique flightless Henderson crake; Oeno hosts 12; Ducie 13 and Pitcairn six species. Birds breeding on Pitcairn include Fairy Tern, Common Noddy and Red-tailed Tropicbird. The Pitcairn Reed Warbler, known by Pitcairn Islanders as a ‘sparrow’, is endemic to Pitcairn Island; formerly common, it is now considered an endangered species.

The four islands have been identified by BirdLife International as separate Important Bird Areas (IBAs). Pitcairn Island is recognised because it is the only nesting site of the Pitcairn Reed Warbler. Henderson Island is important for its endemic land-birds as well as its breeding seabirds. Oeno’s ornithological significance derives principally from its Murphy’s Petrel colony. Ducie is important for its colonies of Murphy’s, Herald and Kermadec Petrels, and Christmas Shearwaters.