This article is about the Chilean archipelago. For other uses, seeJuan Fernández.
TheJuan Fernández Islands (Spanish:Archipiélago Juan Fernández) are a sparsely inhabited series of islands in the South Pacific Ocean, reliant on tourism and fishing. Situated 670 km (362 nmi; 416 mi) off the coast ofChile, they are composed of three mainvolcanic islands:Robinson Crusoe,Alejandro Selkirk, andSanta Clara. The group is part ofInsular Chile.
The islands are primarily known for having been the home to themarooned sailorAlexander Selkirk for more than four years from 1704, which may have inspired English writerDaniel Defoe'sRobinson Crusoe.[1] Most of thearchipelago's present-day inhabitants reside on Robinson Crusoe Island, and mainly in the capital,San Juan Bautista, located at Cumberland Bay on the island's north coast.[2]
Landsat 7 image of the Juan Fernández Islands on 15 September 1999, shows the unique pattern of clouds known as "Kármán vortex street" caused by the interaction of winds with the islands' mountains
Alejandro Selkirk is the largest of the Juan Fernández Islands at 49.5 km2 (19.1 sq mi), and its highest peak,Cerro de Los Inocentes, is also the highest point of the archipelago at 1,268 m (4,160 ft). The island's population was 57 in 2012. Robinson Crusoe is the second-largest island in thearchipelago at 47.9 km2 (18 sq mi); its highest peak, El Yunque, is 915 m (3,002 ft). The population of Robinson Crusoe was 843 in 2012. Santa Clara is 2.2 km2 (0.8 sq mi) in area and reaches a height of 375 m (1,230 ft). Santa Clara is uninhabited.[3] The maximum elevations of Juan Fernández, 915 m (3,002 ft) for Robinson Crusoe and 1,329 m (4,360 ft) for Alejandro Selkirk, respectively, are high enough to cause the phenomenon known asKármán vortex street, which can be seen from space.
The islands arevolcanic in origin, produced by the movement of theNazca Plate over theJuan Fernández hotspot. As the plate moved eastward over the hot spot, volcanic eruptions formed theJuan Fernández Ridge before being subducted under the South American continent at thePeru–Chile Trench. The islands occur where the peaks of the submarine ridge have protruded above sea level.Radiometric dating indicates that Santa Clara is the oldest of the islands, at 5.8 million years old, followed by Robinson Crusoe, 3.8 – 4.2 million years old, and Alexander Selkirk, 1.0 – 2.4 million years old.
Some consider the islands to be one of the easternmost points ofOceania, rather than an outlying region ofSouth America.[5][6] In their bookShore Fishes of Easter Island, authors John E. Randall and Alfredo Cea Egana claim that the Juan Fernández Islands have "great similarity in ichthyofauna with Oceania more so than with the nearing South America."[7]
The archipelago is very diverse in climate taking into account its size, this is due to factors such as its topography which causes the temperature and precipitation regime to change depending on the area of an island. In the Archipelago according toTrewartha's climate classification the windward slopes have asubtropical climate, while areas such as the eastern tip of Robinson Crusoe Island have aSemi-arid climate and the western and leeward areas have aMediterranean climate.[8] The weather is moderated by the coldHumboldt Current, which flows northward to the east of the islands, and thesoutheast trade winds. Temperatures range from 10 °C (50 °F) to 22 °C (72 °F), with an annual mean of 15.4 °C (60 °F). Higher elevations are generally cooler, with occasional frosts on Robinson Crusoe.
Average annual precipitation is 1,081 mm (42.6 in), varying from 318 mm (12.5 in) to 1,698 mm (66.9 in) year to year. Much of the variability in rainfall depends on theEl Niño-Southern Oscillation. Rainfall is higher in the winter months, and varies with elevation and exposure; elevations above 500 m (1,640 ft) experience almost daily rainfall, while the western,leeward side of Robinson Crusoe and Santa Clara are quite dry.
Climate data for Juan Fernández Islands (1991-2020, extremes 1958-present)
TheJuan Fernández Islands are renowned for their unique and diverse flora, characterized by a high degree ofendemism. The archipelago comprises approximately 361 species of vascular plants, including 53 ferns, 65 monocots, and 243 dicots, spanning 73 families and 219 genera. Notably, there is one endemic family (Lactoridaceae), 12 endemic genera, and 126 endemic species, resulting in an endemism rate of 11% at the generic level and 60% at the species level.[13]
Vegetation zones on the islands generally correspond to elevation. Grassy slopes with native and introduced species cover much of the lower altitudes ofRobinson Crusoe Island (Isla Más a Tierra) andAlejandro Selkirk Island (Isla Más Afuera), as well as nearly all ofSanta Clara Island. Tall lowland forests are dominated by the largest trees in the archipelago, includingDrimys confertifolia,Myrceugenia fernandeziana (on Robinson Crusoe Island), andMyrceugenia schulzei (on Alejandro Selkirk Island). All three of these species are endemic to theecoregion and considered vulnerable.[14][15]
In themontane forests of Robinson Crusoe Island, the understory is notably composed of tree ferns such asThyrsopteris elegans, which form dense forests at elevations around 700 to 750 meters. These forests also include species likeDicksonia berteroana and variousBlechnum species. The dominant tree species in these montane forests includeendemic genera such asCuminia,Fagara, andRhaphithamnus.[16]
The flora of theJuan Fernández Islands has been significantly impacted by invasive plant species. On Robinson Crusoe Island, invasive species such as wild blackberry (Rubus ulmifolius) and maqui (Aristotelia chilensis) have colonized 80–90% of the native forest, exerting tremendous pressure on the remaining tracts of forest and the animals that depend on it.[16]
The Juan Fernández Islands have a very limited fauna, with no native landmammals,reptiles, oramphibians. Seventeen land and sea-bird species breed on the islands. The island has three endemic bird species, and three endemic subspecies. Introduced fauna by humans includerats andgoats.Robinson Crusoe Island is home to an endemic and endangeredhummingbird, theJuan Fernández firecrown (Sephanoides fernandensis). This largehummingbird, about 11 cm (4 in) long, is thought to number only about 500 individuals. The other endemic bird species are theJuan Fernández tit-tyrant (Anairetes fernandezianus) of Robinson Crusoe Island, and theMasafuera rayadito (Aphrastura masafuerae) of Alejandro Selkirk Island.[17] The islands support the entire known breeding populations of two petrel species,Stejneger's PetrelPterodroma longirostris (IUCN status VU) and theJuan Fernandez PetrelPterodroma externa (IUCN status VU). In addition, the Juan Fernandez Islands may still support a third breeding petrel species,De Filippi's PetrelPterodroma defilippiana (IUCN status VU), whose only other known breeding grounds are on theDesventuradas Islands. TheMagellanic penguin breeds on Robinson Crusoe Island within thearchipelago.[18] All three islands of the Juan Fernandez archipelago have been recognised asImportant Bird Areas (IBAs) byBirdLife International.[19]
The endemic Juan-Fernandez spiny lobster (without claws) lives in the marine waters (Jasus frontalis). TheJuan Fernández fur seal (Arctophoca philippii) also lives on the islands. This species was nearly exterminated in the sixteenth to nineteenth century, but it was rediscovered in 1965. A census in 1970 found about 750fur seals living there. Only two were sighted on theDesventuradas Islands, located some 780 km (485 mi) to the north. The actual population of the Desventuradas may be higher, because the species tends to hide in sea caves. There seems to be a yearly population increase of 16–17 percent.
A 2008 report by archaeologists from theAustralian National University states that, "a combination of palaeoecology and archaeology in the Juan Fernández Islands showed it was unlikely there had been human activity in the islands before Europeans arrived."[20] IchthyologistsIngo Hahn and Uwe Römer wrote in 2002, "the geographically isolated Juan Fernández Islands were probably untouched by man until their discovery by European sailors in 1574. It is unknown ifPolynesians, or ifnative Americans from South America, reached or settled it at any point."[21]
In the 17th and 18th centuries, the islands were used as a hideout forpirates and became the location of apenal colony. It was during this period thatAlexander Selkirk became marooned on the islands. In the 1740s, they were visited byCommodore Anson's flotilla during his ill-fated venture to the South Seas. The location of thearchipelago was fixed byAlessandro Malaspina in 1790; previous charts had differed on the location.[23] British and Americanwhaling vessels were regular visitors to the islands, starting with theLondon (Captain Joshua Coffin) in 1795.[24]
During themaritime fur trade era of the early 19th century the islands were a source offur seal skins, and theJuan Fernández fur seal was nearly driven to extinction. In his bookTwo Years Before the Mast (Chapter VII),Richard Henry Dana Jr. described the islands as he found them circa 1834. At this time the main island was being used as apenal colony. However, when Dr John Coulter visited it in the early 1840s, he reported the island deserted after the approximately 1000 convicts had risen up, killing the soldiers and Governor who had held them captive. The prisoners fled to mainlandChile, where "great numbers" were later hunted down and shot. The story appears in Coulter's bookAdventures in the Pacific (1845).[25] On 6 May 1846, a ship carrying Mormon missionaries visited the archipelago, re-stocking before travelling onward. During their stop, they buried the body of a pregnant woman, Laura Graham, who had died during a storm.[26]
In 1966 the Chilean government renamed Más Afuera as Alejandro Selkirk Island and Más a Tierra as Robinson Crusoe Island, in order to promote tourism. Incidentally, Selkirk never set foot on Más Afuera, only on Más a Tierra. On 30 July 2007, a constitutional reform gave the Juan Fernández Islands and Easter Island the status of "special territories" of Chile. Pending the enactment of a charter thearchipelago will continue to be governed as a commune of theValparaíso Region.[28]
On 27 February 2010, atsunami following the8.8 magnitude earthquake offMaule, Chile struck the islands causing at least 8 deaths.[29] Eleven people were reported as missing.[30] Some early reports described the tsunami as being 40 m (130 ft) high, but later reports measured it at 3 m (10 ft). Most of the town of San Juan Bautista on Robinson Crusoe Island was destroyed.[31][32][33]
^Thomson, Lex; Doran, John; Clarke, Bronwyn (2018).Trees for life in Oceania: Conservation and utilisation of genetic diversity(PDF). Canberra, Australia: Australian Center for International Agricultural Research. p. 16. Retrieved24 January 2022.In a number of cases, human exploitation of certain high-value tree species, including sandalwoods and other highly prized timbers, has led to their extinction—such as the sandalwood speciesSantalum fernandezianum, in Juan Fernández Islands; and others to the brink of extinction, suchS. boninensis in Ogasawara Islands, Japan; or is an ongoing threatening factor in the examples ofS. yasi in Fiji and Tonga,Gyrinops spp. in Papua New Guinea (PNG) andIntsia bijuga throughout the Pacific Islands.
^Brand, Donald D. (1967).The Pacific Basin: A History of its Geographical Explorations. New York: The American Geographical Society. p. 127.
^Kendrick, John (2003).Alejandro Malaspina: Portrait of a Visionary. Montreal, Quebec: McGill-Queen's Press. p. 46.ISBN0-7735-2652-8.
^Robert Langdon (ed.)Where the whalers went: an index to the Pacific ports visited by American whalers (and some other ships) in the 19th century, Canberra, Pacific Manuscripts Bureau, 1984, p.124.ISBN0-86784-471-X
^Coulter, John (1845).Adventures in the Pacific. W. Curry, jun. and company. pp. 32–33.
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