The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.
Range & Status
Europe; in Britain and Ireland 25,650 pairs. Winters in the South Atlantic.
Cornwall: possibly breeds on islets off north coast (last proven 1968); fairly common offshore from May to September (from Scilly and Welsh colonies probably). Isles of Scilly: the most recent survey in 2006 found 1398 pairs on 11 islands.
Habitat & Ecology
Breeds on offshore islands, visiting breeding colonies undercover of darkness. Otherwise pelagic.
Predation by Brown Rats Rattus norvegicus is a serious threat to colonies. There is some predation by Great Black-backed Gulls Larus marinus but nocturnal attendance of petrels at colonies and decline in gull population indicates that this is of minimal importance.
Thorough census would be difficult; true numbers have yet to be assessed. Continuation of recent rat control on islands where they breed in Scilly is essential. Protected under Annexe 1 of the European Union Conservation of Wild Birds Directive. Listed (long list) as a globally threatened/declining species (BSGR, 1995).
I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.
The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.