Methods
Personal observations have been made of Yellow-legged Gulls on the Atlantic coast in visits to Royan and Isle d'Oléron in south-west France, Santander in northern Spain, Porto and Minho in north Portugal, Lisbon and Setúbal in south-west Portugal, Faro in south Portugal, Tanger in north Morocco lying between the Mediterranean and the Atlantic, Asilah on the north-west Atlantic coast of Morocco, Agadir and Essaouira on the south Atlantic coast of Morocco, Lanzarote, Graciosa, Fuerteventura and Gran Canaria in the eastern Canary Islands, Tenerife and Gomera in the central Canary Islands and La Palma and El Hierro in the western Canary Islands. A total of 18 weeks over 12 years has been spent studying the various forms in the field. The locations visited in the present study, plus Madeira and the Azores, are shown in Figure 1: Locations Visited .
A hope in the field work is that all the Yellow-legged Gulls observed are natives to the areas in which they were found. All visits bar one were made between late March and early September (mainly April and August) by which time most winter visitors will have left except Lesser Black-backed Gull at all sites and variable numbers of Audouin's Gull L. audouinii at localities near the entrance to the Mediterranean. The Lesser Black-backed Gulls were in fact very useful in providing a 'gold standard' against which Yellow-legged Gulls could be directly compared over a wide area. The apparently quite sedentary nature of many Atlantic forms shown later would seem to mitigate against the mixing of the forms at particular localities, at least in the breeding season.
Copyright © Nick Rossiter 1999-2001. All rights reserved.
