Totaaltellingen van meeuwen langs de Belgische kust

After a gap of almost ten years, several total and partial counts of gulls along the Belgian coast have been carried out during the period 1998- 2001. The study area, always counted at low tide, consists of all tidal areas along the coastline: beach, harbours of Nieuwpoort, Oostende, Blankenberge and Zeebrugge (rear port), the Yzer estuary and the Zwin reserve. The Herring Gull Larus argentatus is the most common species and represents 60 tot 70 % of the total number of gulls.The less abundant species is Great Black-backed Gull Larus marinus (5 % of total numbers).The counts also give a clear picture of seasonal differences in number between species, as for Lesser Blackbacked Gull Larus fuscus (summer visitor) and Common Gull Larus canus (winter visitor). Species that are mainly foraging at sea and only come to land to rest, are more found in harbour areas than other species as Herring Gull. During the winter season, 60 to 70 % of the Herring Gulls are adult birds. This proportion is even higher in other species: about 80 % in Great Black-backed Gull and more than 90 % in Lesser Black-backed Gull, Common Gull and Black-headed Gull Larus ridibundus. More counts in the near future will be needed to find out if the seasonal pattern of gull numbers along the Belgian coast is rather constant or is fluctuating strongly between years