Revillagigedo Islands
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- For the island in southeast Alaska, see Revillagigedo Island.
The Revillagigedo Islands (also Revillagigedo Archipelago or Islas Revillagigedo) are a group of islands in the Pacific Ocean, known for their unique ecosystem. They have been part of Manzanillo municipality of the Mexican state of Colima since 1861, but are nevertheless under Mexican federal jurisdiction, and lie 386 km southwest of Cabo San Lucas, the southern tip of Baja California peninsula, and between 720 and 970 km west of Manzanillo. They are located at approximately .
The total area is 157.81 km2. There is a naval station in the south of Socorro Island, with a population of 250 (staff and families). On Clarión, there is a small naval garrison with 9 men. Other than that, the islands are uninhabited. The islands are named after Don Juan Vicente de Güemes Padilla Horcasitas y Aguayo, 2nd Count of Revillagigedo, the 53rd viceroy of New Spain.
The Revillagigedo Islands consist of four volcanic islands, from spread over about 420 from east to west:
| Island (Alternate Name) | Length by width (km) |
Area (km²) | Highest Peak (m) | |
| Inner Islands (UTC-7, Mountain Time) | ||||
| San Benedicto (San Tomás) | 4.315 by 2.490 | 5.94 | Bárcena (310) | |
| Socorro | 16.813 by 15.629 | 132.06 | Mount (Cerro) Evermann (1130) | |
| Roca Partida | 0.246 by 0.073 | 0.014 | (34) | |
| (Outer Island) (UTC-8, Pacific Time Zone) | ||||
| Clarión (Santa Rosa) | 8.544 by 3.686 | 19.80 | Monte Gallegos (335) | |
| Revilla Gigedo Islands | 420 by 115 | 157.81 | Mount (Cerro) Evermann (1130) | |
The three eastern islands are called the inner islands. They fall in the time zone UTC-7 (Mountain Time), while the major part of Colima is UTC-6 (Central Time Zone). Clarión is comparatively far to the west, by more than 200 km in comparison with the inner islands, and in UTC-8 (Pacific Time Zone). The Revillagigedo Islands are one of three Mexican island groups in the Pacific Ocean that are not on the continental shelf; the others are Guadalupe Island and Rocas Alijos.
[edit] History
No evidence of human habitation on the Revillagigedo Islands exists before its discovery by Spanish explorers. Hernando de Grijalva and his crew discovered an uninhabited island on December 21, 1533 and named it "Santo Tomé". Four days later he discovered another, which he named "Inocentes" ("Innocents").
In 1542, Ruy González de Villalobos, while exploring new routes across the Pacific, rediscovered "Inocentes" and changed its name to "Anublada" ("Cloudy"). In 1608, Martín Yañez de Armida, in charge of another expedition, visited Santo Tomé and changed its name to "Socorro" ("Help"). The other two islands were discovered in 1779 by José Camacho. He named the small rocky islet in the middle of the Archipelago "Roca Partida" ("Broken Rock"), and the westernmost island "Santa Rosa" ("Saint Rose"). Santa Rosa was later renamed Clarión ("Clarion").
The Revillagigedo Islands have been visited by a number of other explorers: Domingo del Castillo (1541), Miguel Pinto (1772), Alexander von Humboldt (1811), Benjamín Norell (1825), Sir Edward Belcher (1839) who made the first botanical collections, and Reeve (1848) who witnessed the eruption of Mount Evermann. In 1865, the island was explored by ornithologist Andrew Jackson Grayson, who described the Socorro Dove and Socorro Elf Owl.
On 25 July 1861, President Benito Juárez signed a decree awarding territorial control over the four islands to the state of Colima. His plan was to build an offshore penitentiary on Isla Socorro; although this never happened, the decree whereby they were attached to Colima has never been repealed.
At the beginning of the twentieth century, Dr. Barton Warren Evermann, director of the California Academy of Sciences in San Francisco, California, promoted the scientific exploration of the islands. The most comprehensive biological collections were obtained at this time. The volcano on Isla Socorro was renamed in his honor.
In 1957 the Mexican Navy established a naval base on Socorro, and have had a permanent presence on the island since then. On 21 March 1972, Pablo Silva García became the first governor of Colima to visit his state's island territories. A plaque was unveiled to mark the event and cement Colima's claim.
[edit] Ecology
The Revillagigedo Islands are home to many endemic plant and animal species, and are sometimes called Mexico's "little Galapagos". They are recognized as a distinct terrestrial ecoregion, part of the Neotropic ecozone. Socorro is the most diverse in flora, fauna, and topography. The Mexican Government established the islands as a Biosphere Reserve on June 4, 1994.
The unique ecology of the islands is under threat from exotic species. Sheep were introduced to Socorro in 1869. Several endemic species are now threatened with extinction. The Socorro Mockingbird, (Mimodes graysoni) numbers less than 400 individuals. The endemic Socorro Parakeet, (Aratinga brevipes), the Socorro subspecies of the Elf Owl (Micrathene whitneyi graysoni), and Townsend's Shearwater (Puffinus auricularis), are also endangered. The Socorro Dove (Zenaida graysoni) is now extinct in the wild, but is being bred in captivity.
Several organizations are dedicated to halting the destruction of the native ecosystems of the islands. Dr. Harmunt Walter of the University of California, Los Angeles (UCLA) and Dr. Luis F. Baptista of the California Academy of Sciences have coordinated breeding and reintroduction efforts for the Socorro Dove since 1988, through the Island Endemics Institute. The Comité Científico para la Conservación y Restauración del Archipiélago Revillagigedo (Scientific Committee for the Conservation and Restoration of the Revillagigedo Islands) was founded in 1996, and is a committee representing several organizations, including the Island Conservation & Ecology Group, Island Endemics Institute, the University of Missouri - St. Louis (UMSL), the National Autonomous University of Mexico (UNAM) and others. It is chaired by Dr. Walter and Dr. Luis Medrano of UNAM is its secretary. The committee has been advocating removal of the exotic species from the islands, especially the estimated 2000 sheep on Socorro, to allow the islands' ecology to recover, and adoption of a management plan to promote the recovery of the islands' native species, including reintroduction of the Socorro Dove.
