Ardea
Official journal of the Netherlands Ornithologists' Union

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Voous K.H. (1963) Geographic variation of Larus fuscus in northwestern Europe. ARDEA 51 (1): 16-24
1. Three races of Lesser Black-backed Gull (Larus justus sensu stricto) are recognised and the differences in mantle coloration and migration route are described. 2. Larus fuscus graellsii A. E. Brehm 1857 is the British and Faeroes form. It has the lightest mantle colour, which is at the average 'Neutral Gray' (Ridgway) or 'Dark Gray' (Villalobos). See: 'Handbook of British Birds', 5, plate 135, 'British Lesser Black-backed Gull'. It has a mainly southern and south-western coastal migration route. 3. Larus fuscus juscus Linnaeus 1758 is the Baltic Sea form; it also nests inland in Sweden and Finland. It has the darkest mantle colour, which is at the average 'Fuscous Black' (Ridgway), or between 'Black' and 'Blackish Brown' (Villalobos). There is no satisfactory colour plate of this race in 'The Handbook of British Birds'. It has a mainly south-eastern trans-continental migration route. 4. Larus fuscus intermedius Schioler 1922 is the form from the coasts of Norway and south-western Sweden. It has an intermediate mantle colour running from 'Dark Mouse Gray' to 'Fuscous' (Ridgway) and from 'Blackish Gray' to 'Blackish Brown' (Villalobos). The colour plate in 'The Handbook of British Birds', 5, plate 135, ascribed to the 'Scandinavian Lesser Black-backed Gull' depicts intermedius and not juscus. It has a mainly southern and south-western migration route, like graellsii. 5. Larus fuscus intermedius is the most numerous form of Lesser Black-backed Gull passing along the Netherlands North Sea coast in spring and autumn. 6. Theoretical speculations have been given concerning the geographic origin of the lighter mantled (graellsii) and darker mantled (fuscus) groups in relation to the geographic history of Western Europe and the Baltic Ice Lake during the last glacial period. 7. Larus juscus intermedius is considered to represent a more or less stabilized hybrid form of (mostly) graellsii and (less) fuscus. Nothing is known about the degree of present intergradations of these forms in southern Sweden and Denmark.


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