|Location||St Helena (to UK), Ascension Island|
|Central coordinates||14o 18.00' West 7o 56.00' South|
|IBA criteria||A1, A4i, A4ii, A4iii|
|Altitude||0 - 104m|
|Year of IBA assessment||2001|
Site description The site is a barren, steep-sided trachytic rock, about 340 m by 220 m in size, rising to 104 m, with a relatively flat basaltic top nearly 3 ha in extent, located 305 m north of the eastern part of Ascension Island (SH001). Included also is a small, isolated rock 670 m east of the southern end. The site is heavily overlaid with guano, and there are traces of a guano industry that operated in the 1920s.
Key Biodiversity See Box for key species. Of the 11 resident species of seabirds one, Anous stolidus, does not breed, breeding instead on the main island and stacks (SH001). Breeding species are Oceanodroma castro, Phaethon aethereus, P. lepturus, Sula dactylatra, S. sula, S. leucogaster, Fregata aquila, Sterna fuscata, Anous minutus and Gygis alba. Puffinus lherminieri is thought to have once bred. The world population of F. aquila breeds at this site.
Non-bird biodiversity: The dolphins Steno bredanensis (DD) and Tursiops truncatus (DD) occur, the former common around the island. There are several invertebrates, including the endemic pseudoscorpions Garypus titanius, Neocheiridium sp. and Stenowithius duffeyi.
|Species||Season||Period||Population estimate||Quality of estimate||IBA Criteria||IUCN Category|
|Band-rumped Storm-petrel Hydrobates castro||breeding||1959||1,500 breeding pairs||medium||A4ii||Least Concern|
|Red-billed Tropicbird Phaethon aethereus||breeding||1959||500 breeding pairs||medium||A4ii||Least Concern|
|White-tailed Tropicbird Phaethon lepturus||breeding||1959||1,000 breeding pairs||medium||A4ii||Least Concern|
|Ascension Frigatebird Fregata aquila||breeding||1997||6,000 breeding pairs||medium||A1, A4ii||Vulnerable|
|Masked Booby Sula dactylatra||breeding||1990||1,300 breeding pairs||medium||A4ii||Least Concern|
|Black Noddy Anous minutus||breeding||1990||5,000 breeding pairs||-||A4i||Least Concern|
|A4iii Species group - seabirds||breeding||-||20,000-49,999 individuals||unknown||A4iii|
|Protected area||Designation||Area (ha)||Relationship with IBA||Overlap with IBA (ha)|
|Boatswainbird Island||Protected Area||5||is identical to site||5|
|Land-use||Extent (% of site)|
|nature conservation and research||-|
References Allan (1962), Ashmole (1962, 1963a, b), Ashmole and Ashmole (1997, 2000), Ashmole, Ashmole and Simmons (1994), Blair (1989), Dorward (1962a, b, 1963), Dorward and Ashmole (1963), Duffey (1964), Hughes (1992b), Hughes et al. (1994), Nash et al. (1991, 1992), Osborn (1994), Packer (1983), Ratcliffe (1997), Simmons (1967, 1968, 1970, 1990), Stonehouse (1960, 1962 a, b), Stonehouse and Stonehouse (1963).
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Recommended citation BirdLife International (2015) Important Bird Areas factsheet: Boatswainbird Island. Downloaded from http://www.birdlife.org on 31/03/2015
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