Hybrid gulls in Belgium - an update

This paper provides an update on interbreeding by three species of large white-headed gull at a colony in Zeebrugge, Belgium. Mixed breeding in the colony was studied in detail in 2010, and this account documents some of the known hybrids and their offspring. The results have particular significance for the identification of Yellow-legged Gull Larus michahellis in western Europe, in terms of record assessment in areas where the species is still a rarity, and also in terms of measuring the continuing range expansion of that species.