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Location St Helena (to UK), Ascension Island
Central coordinates 14o 22.00' West  7o 57.00' South
IBA criteria A1, A4i, A4ii, A4iii
Area 9,700 ha
Altitude 0 - 859m
Year of IBA assessment 2001





Site description The site comprises the whole of Ascension Island and the 14 inshore stacks, as well as the marine habitat out to three nautical miles, and is described in the ‘General introduction’.

Key Biodiversity See Box for key species. At least 30 bird taxa are known. There are 11 resident seabird species, Oceanodroma castro, Phaethon aethereus, P. lepturus, Sula dactylatra, S. sula, S. leucogaster, Fregata aquila, Sterna fuscata, Anous stolidus, A. minutus and Gygis alba. Of these, O. castro and F. aquila now breed only on Boatswainbird Island (SH002), but the latter occurs regularly on the main island and both are expected to return as breeders once feral cats are eradicated. In addition, Puffinus lherminieri is thought to have once bred. The main colonies of S. fuscata, by far the most numerous breeding species, are in the south-west of the island, and occupied 9.14 ha in 1997.Although now deserted, many former seabird breeding sites are likely to be reoccupied following the removal of cats. Already, successful recolonization attempts by Sula dactylatra have been noted, e.g. 20 pairs with eggs and chicks at Letterbox in October 1996, and a single pair on a hill at Georgetown from 1993. Both Phaethon aethereus and P. lepturus nest on cliffs opposite Boatswainbird Island and along the south-eastern coast. Anous minutus breeds at Spire Beach, Letterbox, South-east Bay and Cocoanut Bay, while Gygis alba breeds on cliffs inland at Green Mountain and Weatherpost, as well as at South-east Head and opposite Boatswainbird Island. The stacks are important for Anous stolidus (500 pairs) which does not breed on Boatswainbird Island, and also Sula leucogaster and A. minutus.There are five resident landbirds, all introduced; Francolinus afer (introduced 1851), Acridotheres tristis (introduced 1879 and 1880), Passer domesticus (introduced 1985 onwards, Georgetown only), Estrilda astrild (introduced 1860) and Serinus flaviventris (introduced 1890). There are also records of non-breeding visitors and vagrants with fewer than five records. The former include Bubulcus ibis, Gallinula chloropus, Arenaria interpres, Apus apus, Hirundo rustica, and Delichon urbica. In the fossil record, two species are known, an extinct night heron Nycticorax nov. sp. and the extinct flightless rail Atlantisia elpenor.

Non-bird biodiversity: The beaches of Ascension are important breeding grounds for turtles, Chelonia mydas (EN), protected locally since 1926. Hatchlings are taken by feral cats. There is a long list of invertebrates, including two endemic pseudoscorpions Apocheiridium cavicola and Allowithius ascensionis. Yellow and purple land-crabs Gecarcinus lagostoma occur throughout the main island, returning to the sea to breed, laying in shell-sand or soft ash. A shrimp Procaris ascensionis, found in coastal rock pools, is endemic.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Red-billed Tropicbird Phaethon aethereus breeding  1959  55 breeding pairs  A4ii  Least Concern 
Ascension Frigatebird Fregata aquila breeding  present  A1  Vulnerable 
Sooty Tern Onychoprion fuscatus breeding  1997  194,000 breeding pairs  A4i  Least Concern 
Black Noddy Anous minutus breeding  1990  5,000 breeding pairs  A4i  Least Concern 
A4iii Species group - waterbirds breeding  500,000-999,999 individuals  unknown  A4iii   

Land use

Land-use Extent (% of site)
fisheries/aquaculture -
military -
nature conservation and research -
urban/industrial/transport -
not utilised -

References Allan (1962), Ashmole (1962, 1963a, b), Ashmole and Ashmole (1997, 2000), Ashmole, Ashmole and Simmons (1994), Bell and Ashmole (1995), Blair (1989), Chapin (1954), Cronk (2000), Dorward (1962a, b, 1963), Dorward and Ashmole (1963), Duffey (1964), Hughes (1991, 1992a, b, 1994, 1997), Hughes et al. (1994), Nash et al. (1991, 1992), Olson (1973, 1977), Osborn (1994), Packer (1983), Ratcliffe (1997), Ratcliffe and Roberts (1997, 1998), Rowlands (1992), Simmons (1967, 1968, 1970, 1990), Stonehouse (1960, 1962a, b), Stonehouse and Stonehouse (1963), Walmsley (1991, 1992, 1994).

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Recommended citation  BirdLife International (2015) Important Bird Areas factsheet: Ascension Island: mainland and stacks. Downloaded from http://www.birdlife.org on 28/02/2015

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