Alejandro Selkirk Island, previously known as Isla Más Afuera and renamed after Alexander Selkirk, is the second largest and most westernly island of the Juan Fernández Islands archipelago of the Valparaíso Region of Chile. It is situated 168 km (104 mi) west of Robinson Crusoe Island in the southeastern Pacific Ocean.
The island measures 11 km (7 mi) north–south and 6 km (4 mi) east-west, and has an area of 44.6 km2 (17 sq mi). It is densely wooded and very mountainous and is marked by ridges and numerous deep ravines lead to a steep, rugged coast on the east side of the island off which are tremendous depths. The coastal cliffs are up to 1,000 m (3,281 ft) high. The south, west and north sides of the island have sandy strips of beach which extend 161 m (528 ft) offshore in places. The highest peak, Cerro de Los Inocentes, rises to 1,329 m (4,360 ft) at the of the southwest side of Alejandro Selkirk Island, and at the southwest extremity there is a prominent rock with a hole through it.
Alejandro Selkirk has a subtropical climate, moderated by the cold Humboldt Current and the southeast trade winds. Temperatures range from 3 °C (37 °F) to 34 °C (93 °F), with an annual mean of 15.4 °C (60 °F). Higher elevations are generally cooler. 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. Rainfall is higher in the winter months, and varies with elevation and exposure; elevations above 500 m (1,640 ft) experience almost daily rainfall.
Flora and fauna :
The Juan Fernández Fur Seal is known to have existed during the late-17th century on the island with the population of the seals on Alejandro Selkirk Island and Robinson Crusoe Island believed to be in excess of four million by the late 17th century. A census of 1797 estimated a population 2 – 3 million fur seals. The species was hunted to near extinction by the 19th century and was thought to be extinct for 100 years until 200 were found on the island in 1965. Since then, the population has grown at a steady rate of 15 – 20 percent every year.
The Masafuera Rayadito is endemic to Alejandro Selkirk and one of the rarest South American birds with only 140 individuals left. The Alejandro Selkirk Firecrown Sephanoides fernandensis leyboldi an endemic subspecies of the Juan Fernández Firecrown became extinct in 1908 by feral goats and other introduced animals.
The flora on the island is in the Fernandezian Region Floristic Region, in the Antarctic Floristic Kingdom, but often also included within the Neotropical Kingdom. Endemic plant families include Lactoridaceae, with endemic plant genera also found.