SUMMARYBird bones and feathers found in phosphate deposits and fumaroles on Ascension during the B.O.U. Centenary Expedition were used to supplement the historical records in building up a picture of the original avifauna of the island. The remains which can be definitely identified provide strong circumstantial evidence that the sea‐bird colonies on the main island included at least the following species:Oceanodroma castro, Phaethon aethereus, Sula sula, S. dactylatra, Fregata aquilaandSterna fuscata:a skull apparently ofGygis albawas also obtained. No remains definitely referable toPhaethon lepturus, Sula leucogasterorAnous stolidushave yet been found, but it seems very likely that these species also nested in numbers on the main island of Ascension, whileAnous tenuirostris, which still nests on the cliffs of the main island, doubtless also did so in the past.In addition to sea‐birds, a skull and a tarso‐metatarsus of a small rail, found in separate localities, probably represent the extinct flightless species described by Peter Mundy. The rail whose bones were obtained is provisionally considered as a new member of the genusRallus.The only surviving species that is endangered locally is the Red‐footed BoobySula sula: the history of this species on Ascension is di