Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around a thousand miles from the coast of Africa and 1400 miles from the coast of South America, which is roughly midway between the horn of South America and Africa. It is governed as part of the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha, of which the main island, Saint Helena, is around eight hundred miles to the southeast. The territory also includes the remotest populated archipelago on earth, the sparsely populated Tristan da Cunha archipelago, some thirty degrees farther south and about half the way to the Antarctic Circle.
It is primarily a military base, but access has recently improved and the island makes a fascinating destination for seabird enthusiasts. Ascension is a relatively young island of volcanic origin with a hot and usually very dry climate. These conditions have resulted in its flora and fauna being much less diverse than on St Helena. Only some 25 indigenous land plants have been recorded. Ten of these were unique to the island, but four have become extinct. The endemic invertebrates number less than 30 and most of these are tiny inhabitants of crevices in the lava. Just two endemic land birds, the Ascension Rail Atlantisia elpenor and the Ascension Night Heron Nycticorax sp. are known to have existed on Ascension and both are now extinct. Ascension did not have indigenous land mammals, reptiles or amphibians, although the island is an important nesting site for Green Turtles Chelonia midas.
Ascension is, however, a major breeding site for seabirds. The lava plains of the main island and cliffs originally held huge colonies of terns, boobies, frigates, noddies and tropicbirds. Since human colonisation things declined.
Introduced alien species, particularly cats and rats, have had a serious effect on the native wildlife. The seabirds have been particularly badly affected, with most of the larger species deserting the main island to nest on the predator-free stack of Boatswainbird Island, now the only breeding site of the Ascension Frigatebird and with a tiny relict population of Red-footed Boobies. Sooty Terns still maintain large colonies on the main island, breeding at intervals of just over nine months rather than annually. Their numbers have been much reduced by cats but a cat eradication programme has been undertaken and is showing signs of success. Masked Boobies have bred again on the main island and it is hoped that frigatebirds and the other displaced species will also return. Attempts at more effective rat control are also being made.
Number of Species
Number of bird species: 90
African Bird Club
…Ascension is, however, a major breeding site for seabirds. The lava plains of the main island originally held huge colonies of Sooty Terns Sterna fuscata, Masked Boobies Sula dactylatra and the endemic Ascension Frigatebird Fregata aquila. Large numbers of Red-footed Sula sula and Brown Boobies S. leucogaster, Brown Anous stolidus and Black Noddies A. minutus, Fairy (White) Terns Gygis alba and both Red-billed Phaethon aethereus and White-tailed Tropicbirds P. lepturus nested in the sea cliffs and stacks. In contrast to the situation on St Helena, petrels were a relatively minor component of the recent seabird community on Ascension with only Audubon’s Shearwater Puffinus lherminieri (now locally extinct) and Madeiran Storm-petrel Oceanodroma castro nesting there…
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