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).