Henderson Island, which lies in the eastern South Pacific, is one of the few atolls in the world whose ecology has been practically untouched by a human presence. Its isolated location provides the ideal context for studying the dynamics of insular evolution and natural selection. It is particularly notable for the 10 plants and four land birds that are endemic to the island.
Située dans la partie orientale du Pacifique sud, l'île d'Henderson est parmi les rares atolls du monde à avoir conservé une écologie pratiquement intacte. Sa situation isolée permet d'y observer la dynamique de l'évolution insulaire et de la sélection naturelle, et elle est particulièrement remarquable pour ses dix plantes et ses quatre oiseaux terrestres endémiques.
تقع هذه الجزيرة في القسم الشرقي من المحيط الهادئ الجنوبي، وتعتبر احدى الجزر المرجانية النادرة التي حافظت على بيئتها سالمة. ويسمح موقعها المعزول بالتعرف الى دينامية تطور الجزر وعملية الاصطفاء الطبيعي، كما انها تتميز بنباتاتها العشرة وطيورها الأرضية المستوطنة الأربعة.
Остров Хендерсон (Южная Океания)
Остров, лежащий в центральной части Тихого океана, принадлежит к числу тех немногочисленных атоллов, природа которых сохранилась в практически нетронутом виде. Изолированное положение превратило этот атолл в первоклассный научный полигон по изучению процессов эволюции и видообразования. Примечательно, что на острове есть эндемики – 10 видов растений и четыре вида птиц.
Isla de Henderson
Situada en el Pacífico Sudoriental, la isla de Henderson es uno de los pocos atolones del mundo que ha conservado prácticamente intactos sus ecosistemas. Su situación aislada permite observar en buenas condiciones la dinámica de la evolución de las islas y la selección natural de las especies. Es particularmente importante por sus diez especies endémicas de plantas y cuatro de aves terrestres.
Henderson-eiland ligt in het oostelijk deel van de Stille Zuidzee en is een van de weinige koraalatollen ter wereld waarvan de ecologie vrijwel onaangetast is. De geïsoleerde ligging biedt ideale omstandigheden voor het bestuderen van de dynamiek van eilanden-evolutie en natuurlijke selectie. Het grootste deel van de oppervlakte van het eiland is dichtbegroeid met struikgewas en struik-bos van 5 tot 10 meter hoog, het centrale deel is dunner begroeid. Het eiland kent in totaal 51 inheemse bloeiende planten en vier soorten inheemse (ei)landvogels. Er is echter zeer weinig informatie beschikbaar over de eilandecologie of de status van deze vier vogelsoorten.
Outstanding Universal Value
Henderson Island is a remote and uninhabited elevated coral atoll located in the eastern South Pacific. It is the largest of the four islands of the Pitcairn Island group of which only Pitcairn, lying 200 km to its southwest, is inhabited. Covering some 3,700 ha but unsuitable for agriculture and with little fresh water, the island has no major land mass within a 5,000 km radius.
This gem in the middle of the Pacific is one of the world's best remaining examples of an elevated coral atoll ecosystem. It exhibits remarkable biological diversity given the island’s size, with four endemic species of land birds, ten taxa of endemic vascular plants and large breeding seabird colonies. It is of Outstanding Universal Value due to the comparatively low level of disturbance which provides a key for baseline information on similar atolls, and its isolation makes it ideal for studying the dynamics of island evolution and natural selection.
Criterion (vii): As one of the last near-pristine limestone islands of significant size in the world, Henderson Island retains its exceptional natural beauty with its white, sandy beaches, limestone cliffs, and rich and almost undisturbed vegetation. With its vast numbers of breeding seabirds, the island is an outstanding example of a raised and forested oceanic coral atoll with its fundamental features intact.
Criterion (x): While isolated coral atolls are typically species-poor, all four of Henderson’s land birds are endemic including the very distinct flightless Henderson Crake. At least four other endemic and one native species of bird are believed to have become extinct following human colonization. The island today is the only known breeding site of the endangered Henderson Petrel and is an important breeding area for at least ten other seabird species. While the flora is also typically poor with some 57 native vascular species recorded, these include six endemic species, three endemic varieties and another species endemic to Henderson and Pitcairn. As the island has never been intensively studied it seems likely that other as yet unidentified endemics occur. For example, the island's invertebrate fauna is little known but about one-third of the insects and gastropods so far collected are endemic.
Henderson was colonised by Polynesians between the 12th and 15th centuries, but since then the island has remained uninhabited. The inhospitable nature of the island, together with its remoteness and inaccessibility, has so far effectively ensured its conservation. As a near-pristine island ecosystem, it is of immense value for science.
The conditions for integrity are largely met except the need for strengthening the legal status and the implementation of the management plan. Invasive alien species pose the greatest threat to the property. Polynesian Rats, introduced some centuries ago, have been shown to deplete native bird populations. The challenge of preventing new introductions, especially as the island is unguarded and tourists as well as fishermen regularly land on the island, are one of the greatest threats to the continued integrity of the property. Marine pollution with large amounts of plastic debris washed up on the beaches also detracts from the outstanding beauty of the property.
Protection and management requirements
Henderson Island is Crown Land within the Pitcairn Islands group, an Overseas Territory of the United Kingdom. It is subject to the Lands Court Ordinance (Revised Edition of the Laws 2001), Part VII of which gives to the Governor responsibility for possession, occupation, and transference of the lands of the islands. The Wellington-based British High Commissioner to New Zealand holds the office of Governor of Pitcairn.
While the Governor holds most formal powers, much day-to-day administration of the islands’ affairs is devolved to a Commissioner based at the Pitcairn Islands Administration office in Auckland. The Island Council, comprising a Mayor, Secretary, the Chairman of the Internal Affairs Committee, four elected officials, and two appointed advisers, is responsible for the local government and administration of internal affairs within the Pitcairn Islands, including decisions on when to visit any of the other islands in the Pitcairn group. There is also a Conservation and Quarantine Officer whose remit includes Henderson Island. Access to Henderson requires a licence issued by the Governor (through the Pitcairn Island Administration office) in consultation with the Island Council. The local population on Pitcairn includes some 58 inhabitants, making pressure on Henderson Island, located 200 km to its northeast, low. However, visitors from yachts and fishing vessels may arrive to Henderson before arriving at Pitcairn and not know that access is by permit only.
The Henderson Island Management Plan outlines a number of management goals with the principle of working with the Pitcairn Islanders to ensure on-site protection, and to review the legal status of the island with consideration for upgrading it to a Nature Reserve. Specific goals are to ensure that the biological, geological, and archaeological values are conserved, and that stocks of two timber species (Miro Thespesia populnea and Tou Cordia subcordata, both introduced species) are adequate to meet the needs of Pitcairners on a sustainable basis. An ambitious Polynesian Rat eradication programme has been initiated, and measures are being put into place to ensure that no new introductions of alien invasive species occur through regulated tourism. An awareness programme, involving education and research, forms part of this plan.
A number of international conventions relevant to nature conservation and environmental protection have been extended to the Pitcairn Islands. In short, these include the Ramsar Convention on Wetlands; the CITES Convention on Endangered Species in International Trade; the World Heritage Convention; the Bonn Convention on Migratory Species; the Vienna Convention on Substances that Deplete the Ozone Layer; the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter; and the Convention for the Protection of the Environment of the South Pacific Region (SPREP).
Henderson Island is a raised coral atoll which together with Pitcairn, Ducie and Oeno forms part of the Pitcairn Island Group, a Dependent Territory of the United Kingdom in the South Pacific. This is one of the remotest groups of islands in the South Pacific, with no major landmass within a 5,000 km radius. Henderson is an elevated coralline limestone (makatea ) island which rises as an isolated conical mound from a depth of about 3.5 km, and is presumably a reef-capped volcano. The surface of the island is in large part reef-rubble interspersed with areas of dissected limestone, surrounded by steep limestone cliffs undercut on all sides except to the north.
There are three main beaches, to the north, north-west and north-east. Tidal range at spring tides is probably about 1 m, and tides are semidiurnal. The central depression is considered to be an uplifted lagoon.
The island is arid with only one fresh water spring known. It has a very rugged topography, with limestone pinnacles and steep-sided pits, beneath the dense tangled vegetation.
The coastline is one of steep cliffs with fringing reefs on the north and north-west sides.
The vegetation of the island has not been modified to any significant extent, and most of the surface of the island is densely vegetated with tangled scrub and scrub forest 5-10 m tall. The central part of the depression is more sparsely covered. The island has a high degree of endemicity for its size, out of a total of 51 native flowering plant taxa, 10 are endemic. There are no native species of land mammal. All four of the island's land birds are endemic, flightless Henderson rail, Stephen's lorikeet (R),Henderson fruit dove and Henderson warbler. Very little information is available on either the ecology or the status of these four birds. 15 seabirds have been recorded, at least nine of which are thought to breed on the island. The island's invertebrate fauna is also little known but about one-third of the insects and gastropods so far collected are endemic.
Henderson was colonized by Polynesians between the 12th and 15th centuries, but this period of settlement had little ecological impact and the island has remained uninhabited in modern times.
As a near pristine island ecosystem, it is of immense value for science. The inhospitable nature of the island, together with its remoteness and inaccessibility, has so far effectively ensured its conservation.
Henderson Island is the world's only forested atoll with its ecology virtually intact, with ongoing geological and biological processes.Source: UNESCO/CLT/WHC
Henderson-Island has not been declared a protected area as such, although it receives de protection from its isolation, and various restrictions on possession, occupation and transference of lands applied under the Lands and Administration of Estates Ordinance. Some wildlife protection is provided by part IV of the Local Government Regulations.Source: Advisory Body Evaluation