The origin of lesser black-backed gulls larus fuscus wintering in central iberia

Abstract

The origin and age of Lesser Black-backed Gulls Larus fuscus wintering inland on the Iberian Peninsula were mapped using sightings of colour-ringed birds. A total of 288 individuals were sighted over a 17 year period. The gulls originated from seven different countries, with the majority being ringed in the United Kingdom and the Netherlands. The most commonly resighted age group were adults, and most birds were sighted two years after ringing. Our analysis provides evidence for a change in the migration patterns of Lesser Black-backed Gulls, which may be explained by Baker's exploratory migration model. It is probable that the gulls follow the rivers Tagus and Guadiana to the rubbish tips in the inner part of the Iberian Peninsula. The prevalence of adult birds could indicate that Lesser Black-backed Gull has become established as a regular wintering species in the inner part of the Iberian Peninsula. © 2003 British Trust for Ornithology.