Clarion Island

Westernmost of the Revillagigedo Islands

Clarion Island (lang es), formerly Santa Rosa, is the second largest, westernmost and most remote of Mexico's Revillagigedo Islands. The island is located west of Socorro Island and over from the Mexican mainland. It has an area of and three prominent peaks. The westernmost and tallest peak, Monte Gallegos, is high. The central peak is called Monte de la Marina, , and the eastern peak Pico de la Tienda The coasts are backed by perpendicular cliffs, high, with the exception of the middle part of the southern coast in the vicinity of Bahía Azufre (Sulphur Bay), which is the location of a small military garrison with a contingent of 9 soldiers. Two small and at least temporarily brackish pools are the only source of fresh water; even these may dry up in summers with little rain.

As the topography of Clarion lacks any prominent peaks that could induce rains like Cerro Evermann on Socorro Island, the island is semiarid to arid all over. Consequently, the whole of the island is covered in shrubland, grassland and Opuntia are found on the island and have caused serious harm to the local vegetation; pigs introduced in 1979 have caused harm to the local fauna. In addition, the local population of the western raven (Corvus corax sinuatus or C. sinuatus) was formerly considered a distinct subspecies clarionensis, but this is not usually accepted at present. It can be expected that this question will soon be resolved as there is currently renewed interest in the phylogeny of the common/western/Chihuahuan ravens. If the Revillagigedos population is indeed distinct, it might be endemic of Clarión as the only other local subpopulation, on San Benedicto, was destroyed by a volcanic eruption on August 1, 1952;Bulbostylis nesiotica, Cheilanthes peninsularis var. insularis, Cyperus duripes, Euphorbia anthonyi, Nicotiana stocktonii, Perityle socorrosensis, Spermacoce nesiotica and Zapoteca formosa ssp. rosei are Revillagigedo endemics which Clarion shares with either San Benedicto or Socorro. Whether Teucrium townsendii var. townsendii is the same plant as on San Benedicto is not conclusively determined.