Paleornithology of St. Helena Island, South Atlantic Ocean

The present avifauna of St. Helena is a very depauperate one, many species of birds having been extirpated since man's discovery of the island in 1502. The great extent of this extinction was confirmed by a study of over 4600 specimens of fossil and subfossil bird bones, representing 21 species, collected from rich deposits on the island. These deposits vary in age and fall roughly into three groups, the oldest of which extends well back into the Pleistocene, the youngest of which is very recent, and the third is intermediate. The deposits yielded the remains of the following species, six of which are here described as new: Procellariidae—Pterodroma rupinarum, new species, Bulweria bifax, new species, Puffinus pacificoides, new species, P. griseus, P. Iherminieri; Oceanitidae—Pelagodroma marina, Oceanodroma castro; Phaethontidae—Phaethon aethereus; Sulidae—Sula sula, S. dactylatra; Fregatidae—Fregata ariel trinitatis, F. minor; Rallidae—Atlantisia podarces, Porzana astrictocarpus; Charadriidae—Charadrius sanctaehelenae; Laridae—Larus sp., Gygis alba, Sterna fuscata; Columbidae—Dysmoropelia dekarchiskos, new genus and species; Cuculidae—Nannococcyx psix, new genus and species; Upupidae—Upupa antaios, new species. Pterodroma rupinarum and Puffinus pacificoides belong to species-groups that presently occur in the Indo-Pacific but not in the Atlantic; no gadfly-petrel of the size of Bulweria bifax is found in the Atlantic today. Puffinus griseus and Larus sp. are thought merely to have been vagrants on St. Helena. The pigeon and the hoopoe were both large and probably flightless. Differences in the composition and relative abundance of species between the deposits of different age indicate that the marine environment at St. Helena became progressively more tropical late in the Pleistocene. This resulted in great decreases in, or even extinction of, some of the species of Procellariiformes and in the appearance later in the fossil record of more purely tropical seabirds such as boobies, frigatebirds, and Sooty Terns. - Content source: DLC