The Territories Southern Oceans Pitcairn Islands Banner Image: Pitcairn. Copyright: Stewart McPherson www.britainstreasureislands.com The Pitcairn Islands are a group of four small, remote and varied South Pacific islands, comprising a total area of only 43 km2. They range from Pitcairn itself (4.5 km2), a geologically recent volcano, to Henderson Island, a 37 km2 raised coral atoll and the largest island, and low-lying coral atolls of Oeno (15 km2, maximum elevation of 1-2 m) and Ducie (6.4 km2, of which 0.74 km2 is emergent land raising 1-2m above sea level). The nearest continental land-masses are over 4,500km away, New Zealand to WSW and South America to the east. Oeno Island, one of the two low atolls in the group. Copyright: Dr Mike Pienkowski Only Pitcairn is inhabited, and well known for being the home of the descendants of the sailors who took part in the famous mutiny on HMS Bounty in 1789. The small community of less than 50 lives at Adamstown, isolated by more than a day’s ship or boat journey from its nearest neighbours in French Polynesia, around 500km NW. The volcanic island is relatively young, at 0.75 – 1 million years old, reaching a maximum altitude of 329 m with steep slopes and volcanic soils, varying from red to black in different locations. Henderson Island, the largest in the group, was designated a World Heritage Site by UNESCO in 1998. Tourism is the main economic driver on the island, along with subsistence agriculture and fishing, but many have jobs in government. Provisions, such as fruit and honey, are produced as a result of the rich volcanic soils, and are sold to visiting cruise ships, as well as - in the case of honey - sold to international customers as the purest honey in the world. The Governor of Pitcairn is the Wellington(NZ)-based British High Commissioner, and an appointed Governor’s Representative resides on the island for one-year secondments. 367 plant species have been recorded for the Pitcairn Islands group, of which 147 are native to these islands and to the neighbouring region of French Polynesia and 19 are endemic to the Pitcairn Islands group. Due to the geological differences between the islands, plant species are not spread evenly between them, with Ducie supporting just 3 native plant species and Oeno 18. Neither atoll has any endemic plants, due to the limited range of suitable habitats on these islands. As Henderson Island is a raised atoll with no human inhabitants, it supports the most intact flora that has suffered little disturbance and contains no exotic plant species. It is one of the ecologically most intact remaining islands in the Pacific. A total of 55 native plants grow on Henderson, of which 9 are endemic. Pitcairn Island has a greater variety of ecological niches, and so plant species on the island are more diverse, with 81 native species, of which 9 are endemic. Two of these are now unfortunately extinct in the wild, including the national flower yellow fatu Abutilon pitcairnense rediscovered in 2003, but now extinct in the wild due to a landslide destroying the last remaining plant. However, seeds have been banked in several collections in and outside of Pitcairn. Flightless Henderson rail, one of the Island’s 5 endemic bird species. Copyright: Dr Mike Pienkowski Fifty one of the native vascular plants are threatened; the endemic Coprosma benefica, known from only 11 individuals, and the endemic fern Angiopteris chauliodonta are restricted to small and fragmented populations. Several factors pose threats to the native vegetation, exacerbated by them being restricted to small areas of suitable habitats. This includes habitat loss caused by humans, and the significant threat from the spread of introduced species – there are approximately 250 species that have been introduced and compete with native habitats. A pair of Kermadec petrels on nesting site at Ducie Island and (below) a pair in display flight over the breeding grounds at the Island. Several species of petrels breed on Ducie, Henderson and Oeno Island, in some cases constituting major parts of the world populations. Copyright: Dr Mike Pienkowski The Pitcairn Islands support large and globally important populations of sea-birds, including approximately 90% (200,000 breeding pairs) of the global population of Murphy’s petrel (nesting on Ducie). They also support Herald and Kermadec petrel populations and one of the largest colonies of Christmas shearwaters. Christmas shearwater Puffinus nativitatis, Ducie Island. Copyright: Dr Mike Pienkowski Henderson Island is one of the world’s best remaining examples of an elevated coral atoll ecosystem and remains little disturbed due to its remoteness and inhospitable nature. The island plateau is what was formerly the lagoon floor, lifted to an elevation of about 30 m by the Earth’s crust flexing when Pitcairn itself was formed. As a result, it is largely protected from the periodic inundation of the sea during cyclones, and so is cloaked in dense vegetation, growing on limestone soil and coral rubble. This has allowed the continued existence on the island of colonizing species and, as a result, a diverse fauna and flora has developed with many endemic species. These include the Henderson rail, Henderson lorikeet, Henderson fruit-dove, Henderson reed-warbler and the endangered Henderson petrel that breeds here. Bristle-thighed curlew Numenius tahitiensis at Henderson. Breeding in Alaska and wintering in the Pacific islands, this species makes some of the world’s longest continuous migratory flights. Copyright: Dr Mike Pienkowski Also, 7 of 16 species of land snails and 9 of 63 native vascular plant species are endemic to Henderson Island, as well as a high diversity of invertebrates, many of which are likely to be native/ endemic. A small number of green turtles nest on the east beach of Henderson. Henderson’s unique biodiversity is threatened due to the presence of introduced Pacific rats that have a particularly devastating effect on the petrel chicks. It is believed that seabird numbers in general have dropped from an estimated 5 million pairs before rats arrived to just 40,000 pairs. In 2010, ground-breaking efforts were made to remove rats from Henderson (the largest tropical or sub-tropical island ever to be subject to a rat eradication operation), but unfortunately a weather change thwarted complete eradication. These efforts continue through the Henderson Island restoration programme. Pacific rats were removed successfully from Oeno and Ducie in the 1990s. Studies on the marine environment in recent years have revealed incredibly healthy ecosystems. Over 350 species of fish have been recorded around Pitcairn, with several inshore fish known only from Pitcairn Islands. These include: the squirrelfish Sargocentron megalops, the many-spined butterflyfish Hemitaurichthys multipinous, the sand lance Ammodytes sp, the triplefin Enneapterygius ornatus, and Alticus sp. Around 240 marine molluscs are known, of which about two percent are endemic. One species of liotinine gastropod, belonging to a single genus (and therefore species), is known only from Oeno. The deep sea around Pitcairn contains approximately 400 sea-mounts which provide important habitat for many deep-sea fish and invertebrates. 22 species of cetaceans are found, including blue whale, sei whale, fin whales and humpback whales. Humpback Whales close to Henderson Island. Photo: Steve Darroch 2016 saw the legal designation of Pitcairn Island Marine Reserve which, at 834,000 km2, is one of the largest fully protected marine reserves in the world. Residents can still engage in sustenance fishing within 12 nm of the island’s coasts, but all commercial extractive activity is prohibited. Gray reef shark patrols over the coral reef and below SV Southern Cross, Ducie Island. Copyright: Capt. Paul Green A virtual tour for Pitcairn Islands, outlining their historical and cultural importance, is available here (opens in new window).