Cosmoledo Atoll from the air
|Area||5.09 km2 (1.97 sq mi)|
|Outer Islands||Aldabra Group|
|Density||0 /km2 (0 /sq mi)|
The atoll is 14.5 km long east-west, and 11.5 km north-south. The total land area is about 5.2 km², while the lagoon measures 145 km² in area (total 152 km²). It is located at . The closest island is Astove Island, 38 km farther south. Cosmoledo Atoll is part of the Aldabra Group.
Cosmoledo Atoll is a raised coral atoll of 460 ha land and a lagoon of 14,500 ha up to 8.2 metres deep. Geologically, it is the twin of Astove, standing on the same volcanic basement measuring 85 km from north to south and 52 km from east to west and rising from a depth of over 4 km. The two peaks join at a depth of around 1 km. Unlike the steep wall of Astove, the sea floor falls gradually to about 50 metres over a distance of up to a kilometre then more steeply reaching 500 metres in about 1.5 km. Two main passes lead from the ocean to the shallow lagoon, one northwest of South Island and one (Grande Passe) between Pagode and Grande Ile (or Wizard). On the western coast, elevated reef rock forms undercut headlands mirroring the waves of the sea and separated by sandy beaches. There are sand dunes in the north and south, rising to about 10 metres. The Constitution of Seychelles names 19 islands although there are also a number of unnamed islets. The largest are Menai (in the west) and Wizard Island (Grande Île, in the southeast). The other islands, named in the Constitution are Île du Nord (West North), Île Nord-Est (East North), Île du Trou, Goëlettes, Grand Polyte, Petit Polyte, Pagode, Île du Sud-Ouest (South), Île aux Moustiques, Île Baleine, Île aux Chauve-Souris, Île aux Macaques, Île aux Rats, Île du Nord-Ouest, Île Observation, Île Sud-Est and Ilot la Croix).
In 1878, Sergeant Rivers reported that judging by the turtle remains on the beach, fishermen and whalers frequently called. He found a recently destroyed hut and ‘turtle park’ on Menai; a hut on Wizard built from the wreckage of the Merry Monarch (wrecked in April 1874), which had been burnt. He reported that Menai was virtually covered with tall mangroves. Cosmoledo was settled shortly after this and a visitor in 1895, noted 200-300 coconut trees, maize and goats. By 1901 there were just two men on Menai, one on Wizard and four on Ile Nord-est. Exploitation of guano on Ile Nord-est was taking place in 1901, when 120 tons had been removed. A few years layer, mangrove bark had become an important product; it was dried and exported for tannin. The atoll was inhabited as a fishing and turtling station until 1992 when it was abandoned.
Flora and Fauna
Cosmoledo is an Important Bird Area and holds Seychelles' largest colonies of all three species of booby that breed in Seychelles. The atoll holds the last viable population of Brown Booby, breeding mainly on Ile du Sud Ouest, with a few on Ile du Nord. It also has the Indian Ocean's largest population of Red-footed Booby censused by the Island Conservation Society as about 15,000 pairs. Exploitation has wiped out the Lesser Frigatebird and has almost done the same to the Great Frigatebird, which is down to just 10–20 pairs compared to hundreds of pairs in the 1970s. Despite this, hundreds of non-breeding frigatebirds of both species are to be seen, these being probably from Aldabra. The Lesser Frigatebird also once bred but now may be extinct. Cosmoledo also has Seychelles' largest colony of Sooty Tern breeding on the northern end of Grand Ile (Wizard). Second only to Aldabra are the numbers of breeding Red-tailed Tropicbird, Black-naped Tern and Crested Tern.
The lagoon is an important feeding ground for migratory waders, with Crab Plover and Ruddy Turnstone most common. There are three endemic races of land bird: the Madagascar White-eye (race menaiensis), the Souimanga Sunbird (race buchenorum) and a particular form of Madagascar Turtle Dove. The Madagascar Cisticola is also common and there are a few Pied Crow present.
The flora is similar to that of Aldabra, with fewer species but including several plants endemic to the group. As on Aldabra there are areas of tall mangrove, especially on the lagoon side of Menai. Coconuts are common only on Menai, where many were planted.
Lizards include Bouton’s snake-eyed skink and Madagascar banded lizard, the latter found nowhere else in Seychelles. Green turtle nest in reasonably large numbers, despite decades of exploitation in the past and poaching in the present. The reefs are spectacular and offer some of the best diving in Seychelles.
The Island Conservation Society has carried out conservation and rehabilitation work on the atoll, including the eradication of introduced rats and cats on several islands.
|Wikimedia Commons has media related to Cosmoledo Atoll.|
- Rocamora, G. Feare C.J., Skerrett, A., Athanase, M. and Greig, E. 2003. The breeding avifauna of Cosmoledo Atoll (Seychelles) with special reference to seabirds: conservation status and international importance. Bird Conservation International 13: 151-174.
- Atoll Research Bulletin vol. 83 "Notes on some of the Seychelles Islands, Indian Ocean"
- Atoll Research Bulletin vol. 136 "Coral islands of the Western Indian Ocean" (map of Cosmoledo, p. 139)
- Satellite Images
- Island Conservation Society