Cornish Biodiversity Network  -  Supporting Wildlife Recording

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Cornish Red Data (2009)

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.

Uria aalge - Guillemot

Range & Status

Holarctic; in Britain and Ireland 1.5 million breeding pairs (chiefly in north).

Regional Distribution

Cornwall: breeds at scattered sites along north and west coast and on south coast east to Nare Head. Some 1300 birds counted at breeding sites during 1985-87 survey, indicating slight increase since 1967-70 survey (Smaldon, 1986 and 1988). 1661 birds counted on ledges in 2000 survey. Isles of Scilly: some 155 pairs at three islands in 2006.

Habitat & Ecology

Breeds colonially on sheer, exposed, coastal cliffs. Birds on Scilly nest amongst boulders in manner of Razorbills Alca torda , rather than on cliff faces. Remains at sea between breeding seasons.


Marine pollution, inshore fishing (monofilament nets), and food shortages.


Monitoring of breeding numbers.


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.

Cornish Biodiversity Network. 2017.