Clarion Island (Spanish: Isla Clarión), formerly Santa Rosa, is the second largest, westernmost and most remote of Mexico'sRevillagigedo Islands. The island is located 314 kilometres (195 mi) west of Socorro Island and over 700 kilometres (430 mi) from the Mexican mainland.
It has an area of 19.80 square kilometres (7.64 sq mi)[1] and three prominent peaks. The westernmost and tallest peak, Monte Gallegos, is 335 metres (1,099 ft) high. The central peak is called Monte de la Marina, 280 metres (920 ft), and the eastern peak Pico de la Tienda 292 metres (958 ft). The coasts are backed by perpendicular cliffs, 24 to 183 metres (79 to 600 ft) 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[citation needed].
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.[2] Clarion can only be reached by sea, which from Mexico takes 30 hours.
History
No signs to indicate prehistoric human activity have ever been found on Clarion Island. It was visited in late 1542 by the Spanish navigator Ruy López de Villalobos, but with the exception of a possible re-sighting of the Revillagigedos by Juan Fernández de Ladrillero before 1574 and a short-lived residence by the adventurer Martín Yáñez de Armida on the island he later renamed Socorro (1606), the archipelago was neglected by the Spaniards. Joris van Spilbergen's sighting of the whole group in December 1615 seems not to have been noted in Spain or its American colonies.
Clarion was sighted again by the English privateer George Shelvocke on the Speedwell, August 21, 1721.
The name of the island goes back to the American brig Clarion, Capt. Henry Gyzelaar, who was engaged in the North Pacific trade around 1820.[3]
The Handbook of Selected Pacific Islands (1959), by Edwin B. Doran, observed that "Clarion has never been occupied by man for more than a few days at a time", adding that "there are no facilities of any sort at present."[4]
Ecology
Clarion Island – Marplot Map (1:50,000)
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[note 1] and Opuntia[note 2][2]cacti. Far away from land, endemictaxa are fewer than on Socorro but like there mainly consist of landbirds and plants. Rabbits and feralsheep[5] 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.[6][7] Native vertebrates – except birds – are limited to two snake species and one iguanid lizard species, both endemic.
A few seabird species breed on Clarion or formerly did so. The island is near the north(east)ern limit of the breeding range of several of these, but their continued presence needs confirmation:
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;[2] on the other hand, mainland birds have sometimes been assigned to clarionensis also.
The Clarión population of the critically endangeredTownsend's shearwater (Puffinus auricularis) was probably extirpated in 1988 due to the feral pigs' depredations on the young and nesting birds.[7]
Brickellia peninsularis var. amphithalassa[10]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.[9]
There has not been recent dedicated research on the impact the sheep and rabbits had on the local flora.[9] While no plants seem to have gone extinct on the other Revillagigedo Islands, Clarion is one most heavily affected by introduced herbivores.[6][7]
^Howay, Frederic William & Pierce, Richard A. (1973): A list of trading vessels in the maritime fur trade, 1785–1825 (Materials for the study of Alaska history). The Limestone Press, Kingston, Ontario. ISBN0-919642-51-9
^Méndez-Guardado, Pedro (2001). "Analysis of the Environmental Impact Caused by Introduced Animals in the Clarion Island, Archipelago of Revillagigedo, Colima, Mexico". Global Change and Protected Areas. Advances in Global Change Research. Vol. 9. pp. 323–329. doi:10.1007/0-306-48051-4_31. ISBN978-90-481-5686-3.
^Mulcahy, D.G. Martínez-Gómez, J.E., Aguirre-León, G., Cervantes-Pasqualli, J.A. & Zug, G.R. 2014. Rediscovery of an Endemic Vertebrate from the Remote Islas Revillagigedo in the Eastern Pacific Ocean: The Clarión Nightsnake Lost and Found. PLOS One. doi:10.1371/journal.pone.0097682
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