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
West Medierranean: breeds on small islets within the Balearic Islands (Spain) with 70% about Formentura. Disperses through the Straits of Gibraltar after breeding, heading north into the Bay of Biscay following the Gulf Stream north into the mouth of the English Channel. Some reach west Scotland. It is considered to be ' mainland' Europe' s most endangered bird. Population estimated at 3300 pairs in 1991, but down to about 2000 pairs ten years later. However, counts of birds heading west through the Straits of Gibraltar indicate it could be considerably higher.
Cornwall: small to moderate, but significant numbers feed offshore in small parties. Occurs off both north and south coasts chiefly between July and October, but small and increasing numbers also winter in Cornish waters. Concentrated coordinated seawatching by ' SeaWatch SW' during 2007 produced a cumulative total of 1200 from the continuously watched Gwennap Head (Porthgwarra). This was replicated in 2008. Isles of Scilly: far fewer with most sightings being of singles during seawatches.
Habitat & Ecology
Pelagic. Reliant on shoals of Sardines Sardina pilchardus and Anchovies Stolephorus encrasicolus which are now found nearer to Cornwall in winter due to increase in sea temperature during the 1990s. Consequently, birds have to travel 400 miles further than previously to reach the main feeding areas.
Predation by introduced cats Felis catus , Genets Genetta genetta and Brown Rats Rattus norvegicus on breeding islands; also increased tourist pressures. Overfishing of vital fish stocks. Unknown numbers are hooked by long-line fishing boats. Oiling incidents. Higher than normal mercury levels in the sea off NE Spain.
All breeding sites are now protected by the Balearic government with plans to eradicate mammalian predators. In 2007 species was placed on IUCN Red List as ' critically endangered' . The introduction of Marine Conservation Zones with further monitoring of numbers through coordinated sea-watching effort.
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.