The Juan Fernández Islands (Spanish: Archipiélago Juan Fernández) are a group of islands in the South Pacific Ocean with few people living there. They depend on tourism and fishing for their economy. Located 670 km (362 nmi; 416 mi) from the coast of Chile, the islands include three main volcanic islands: Robinson Crusoe, Alejandro Selkirk, and Santa Clara. These islands are part of Insular Chile.

The islands are most famous for being the home of Alexander Selkirk, a sailor who was left stranded there for more than four years starting in 1704. This experience may have inspired the story of Robinson Crusoe by English writer Daniel Defoe. Most people who live on the islands today are on Robinson Crusoe Island, and many live in the capital city, San Juan Bautista, which is located at Cumberland Bay on the island’s north coast.

The Juan Fernández Islands are part of Chile’s Valparaíso Region, which also includes Easter Island. Along with the Desventuradas Islands, they form the commune of Juan Fernández, one of the nine communes in Valparaíso Province. The islands are named after Juan Fernández, the explorer who discovered them in the 1570s.

Geography

Robinson Crusoe Island (33°38′00″S 78°51′00″W) is also called Isla Más a Tierra. It is the closest island to the mainland of South America and is surrounded by smaller islands, including Juanango, Viñilla, Los Chamelos, Los Claveles, and El Verdugo. Santa Clara (33°42′07″S 79°00′05″W) is located 1 km southwest of Robinson Crusoe Island.

Alejandro Selkirk Island (33°46′00″S 80°47′00″W) is also called Isla Más Afuera. It is 180 km farther west than Robinson Crusoe Island.

Alejandro Selkirk Island is the largest in the Juan Fernández Islands, covering 49.5 km². Its highest point, Cerro de Los Inocentes, reaches 1,268 m. The island had a population of 57 in 2012. Robinson Crusoe Island is the second-largest, covering 47.9 km². Its highest point, El Yunque, is 915 m. The island had a population of 843 in 2012. Santa Clara is the smallest, covering 2.2 km², and reaches 375 m. Santa Clara has no permanent residents.

The highest points on the islands—915 m on Robinson Crusoe and 1,268 m on Alejandro Selkirk—are tall enough to create a weather pattern called the Kármán vortex street, which can be seen from space.

The islands were formed by volcanic activity caused by the movement of the Nazca Plate over a hotspot called the Juan Fernández hotspot. As the plate moved east, volcanic eruptions created the Juan Fernández Ridge, which was later pushed under the South American continent at the Peru–Chile Trench. The islands are the parts of this underwater ridge that rose above sea level.

Radiometric dating shows that Santa Clara is the oldest island, about 5.8 million years old. Robinson Crusoe is 3.8 to 4.2 million years old, and Alejandro Selkirk is 1.0 to 2.4 million years old.

The ocean floor near the Juan Fernández Islands contains manganese-iron nodules, which may have economic value.

Some scientists consider the islands part of Oceania rather than South America. In their book Shore Fishes of Easter Island, authors John E. Randall and Alfredo Cea Egana note that the fish species found on the islands are more similar to those in Oceania than to those in South America.

Climate

The group of islands has many different climates because of its size and the shape and height of the land. These factors cause temperature and rainfall patterns to change depending on the island’s location. According to Trewartha’s climate classification, the windward slopes have a subtropical climate, while the eastern tip of Robinson Crusoe Island has a semi-arid climate, and the western and leeward areas have a Mediterranean climate. The weather is influenced by the cold Humboldt Current, which flows northward along the east side of the islands, and the southeast trade winds. Temperatures range from 10°C (50°F) to 22°C (72°F), with an average of 15.4°C (60°F) each year. Higher areas are usually cooler, and Robinson Crusoe occasionally experiences frost.

On average, the islands receive 1,081 mm (42.6 in) of rainfall each year, with amounts ranging from 318 mm (12.5 in) to 1,698 mm (66.9 in) yearly. Rainfall changes depending on the El Niño-Southern Oscillation. More rain falls during winter months, and rainfall amounts depend on elevation and sunlight exposure. Areas above 500 m (1,640 ft) receive rain almost every day, while the western, leeward sides of Robinson Crusoe and Santa Clara are much drier.

Biota and ecology

Juan Fernandez Island in Chile has many rare and endemic plants and animals. It is recognized as a distinct ecoregion. The volcanic origin and remote location of the islands meant that plants and animals had to travel far across the sea to reach the archipelago. As a result, the island has relatively few plant species and very few animal species. The closest relatives of the archipelago’s plants and animals are found in the Temperate broadleaf and mixed forests ecoregions of southern South America, including the Valdivian temperate forests, Magellanic subpolar forests, and San Félix–San Ambrosio Islands temperate forests.

The Juan Fernández Islands are known for their unique and diverse plants, which include a high number of species found only in this region. The archipelago has about 361 species of vascular plants, including 53 ferns, 65 monocots, and 243 dicots. These plants belong to 73 families and 219 genera. Notably, there is one family (Lactoridaceae), 12 genera, and 126 species that are found only on the islands. This means 11% of the plant genera and 60% of the plant species are unique to the islands.

Vegetation on the islands is often grouped by elevation. Grassy slopes with both native and introduced plants cover much of the lower areas of Robinson Crusoe Island (Isla Más a Tierra) and Alejandro Selkirk Island (Isla Más Afuera), as well as nearly all of Santa Clara Island. Tall lowland forests are dominated by the largest trees in the archipelago, including Drimys confertifolia, Myrceugenia fernandeziana (on Robinson Crusoe Island), and Myrceugenia schulzei (on Alejandro Selkirk Island). All three of these species are found only on the islands and are considered vulnerable.

In the montane forests of Robinson Crusoe Island, the understory is made up of tree ferns such as Thyrsopteris elegans, which form dense forests at elevations around 700 to 750 meters. These forests also include species like Dicksonia berteroana and various Blechnum species. The main tree species in these forests include endemic genera such as Cuminia, Fagara, and Rhaphithamnus.

The plants on the Juan Fernández Islands have been greatly affected by invasive species. On Robinson Crusoe Island, invasive plants like wild blackberry (Rubus ulmifolius) and maqui (Aristotelia chilensis) have taken over 80–90% of the native forest. This has put pressure on the remaining forest and the animals that depend on it.

Maps and satellite images of the islands include:
– A map of Robinson Crusoe Island (including Santa Clara Island)
– A map of Alejandro Selkirk Island
– A map of both islands
– Satellite images of Juan Fernández Islands (with an inset of Alejandro Selkirk Island)
– An overview map

The Juan Fernández Islands have very few native land mammals, reptiles, or amphibians. Seventeen land and sea-bird species breed on the islands. Three bird species and three bird subspecies are found only on the islands. Humans have introduced rats and goats to the islands. Robinson Crusoe Island is home to an endemic and endangered hummingbird, the Juan Fernández firecrown (Sephanoides fernandensis). This large hummingbird, about 11 cm (4 in) long, is thought to have only about 500 individuals. Other endemic birds include the Juan Fernández tit-tyrant (Anairetes fernandezianus) on Robinson Crusoe Island and the Masafuera rayadito (Aphrastura masafuerae) on Alejandro Selkirk Island. The islands support the entire known breeding populations of two petrel species, Stejneger's Petrel (Pterodroma longirostris) and the Juan Fernandez Petrel (Pterodroma externa), both of which are classified as vulnerable by the IUCN. The islands may also support a third petrel species, De Filippi's Petrel (Pterodroma defilippiana), which is also vulnerable. The Magellanic penguin breeds on Robinson Crusoe Island. All three islands of the Juan Fernández archipelago have been recognized as Important Bird Areas (IBAs) by BirdLife International.

The endemic Juan-Fernandez spiny lobster (Jasus frontalis) lives in the marine waters around the islands. The Juan Fernández fur seal (Arctophoca philippii) also lives on the islands. This species was nearly wiped out between the 16th and 19th centuries but was rediscovered in 1965. A census in 1970 found about 750 fur seals on the islands. Only two were sighted on the Desventuradas Islands, located about 780 km (485 mi) to the north. The actual population on the Desventuradas may be higher because the seals hide in sea caves. The population increases by about 16–17% each year.

History

A 2008 report by archaeologists from the Australian National University explains that studies of ancient environments and archaeological findings in the Juan Fernández Islands suggest there was probably no human activity there before Europeans arrived. In 2002, fish experts Ingo Hahn and Uwe Römer wrote that the Juan Fernández Islands, which are far from other landmasses, were likely not visited by humans until European sailors discovered them in 1574. It is not known if Polynesians or people from South America ever reached the islands.

The islands were discovered on November 22, 1574, by a Spanish sailor named Juan Fernández. He was sailing between Callao and Valparaíso and found the islands hundreds of miles west of Chile’s coast. He avoided the Humboldt current, which flows northward. He named the islands Más Afuera, Más a Tierra, and Santa Clara.

In the 17th and 18th centuries, the islands were used as hiding places by pirates and later became a site for a prison colony. During this time, Alexander Selkirk was stranded on the islands. In the 1740s, Commodore Anson’s fleet visited the islands during a failed journey to the South Seas. The exact location of the islands was determined by Alessandro Malaspina in 1790, as earlier maps had shown different positions. British and American whaling ships, starting with the London (led by Captain Joshua Coffin) in 1795, frequently visited the islands.

During the early 19th century, the islands were a source of fur seal skins. This led to the near extinction of the Juan Fernández fur seal. In his book Two Years Before the Mast, Richard Henry Dana Jr. described the islands around 1834, when the main island was still a prison colony. However, by the early 1840s, Dr. John Coulter reported that the island was empty after about 1,000 prisoners had rebelled, killed their captors, and fled to mainland Chile. Many of the escaped prisoners were later hunted and killed. This story is written about in Coulter’s book Adventures in the Pacific (1845). On May 6, 1846, a ship carrying Mormon missionaries stopped at the islands to restock supplies before continuing their journey. During their visit, they buried the body of Laura Graham, a pregnant woman who had died during a storm.

In 1908, the islands were visited by the Swedish Magellanic Expedition. Carl Skottsberg is believed to have been the last person to see the Santalum fernandezianum tree alive.

In late 1914, the islands were a meeting place for Admiral Maximilian von Spee’s East Asia Squadron before he defeated British forces at the Battle of Coronel. After the British won the Battle of the Falkland Islands a month later, the only surviving German ship, SMS Dresden, was hunted and cornered at Más a Tierra in early 1915. Though the ship was in Chilean waters, it was scuttled after a short battle with British cruisers.

In 1966, the Chilean government renamed Más Afuera as Alejandro Selkirk Island and Más a Tierra as Robinson Crusoe Island to encourage tourism. Interestingly, Selkirk never visited Más Afuera, only Más a Tierra. On July 30, 2007, a constitutional reform gave the Juan Fernández Islands and Easter Island the status of “special territories” in Chile. Until a charter is created, the islands will remain governed as part of the Valparaíso Region.

On February 27, 2010, a tsunami caused by an 8.8 magnitude earthquake near Maule, Chile, hit the islands. The tsunami caused at least 8 deaths and left 11 people missing. Early reports said the wave was 40 meters (130 feet) high, but later measurements showed it was 3 meters (10 feet) high. Most of the town of San Juan Bautista on Robinson Crusoe Island was destroyed.

Government

The Juan Fernández Islands are part of the Juan Fernández commune, a local area in Chile managed by a municipal council. This council is led by a mayor, called alcalde in Spanish, who is chosen by voters every four years. The mayor for the period 2021–2024 was Pablo Andrés Manríquez Angulo.