Rui en plaatstrouw van Zilvermeeuw Larus argentatus ZDGA op grond van Kleurringaflezingen

One of the more comprehensive colour-ring studies on large gulls in The Netherlands was launched in the mid-1980s. This study involved the annual ringing of c. 100 fledglings in 12 (later 14) colonies of Herring Gulls scattered along the Dutch coastline between 1986 and 1988. Nearly 90 000 documented sightings of Herring Gulls ringed in these years have been processed and are currently available for analysis. This paper provides details of one, particularly old individual bird, colour-ringed as a chick with code ZDGA (Black D left, Green A right. ZDGA in Dutch) in Wassenaar in 1986, now over 24 years old and one of at least four similarly aged individuals from the same ringing campaign still alive. The bird was re-discovered in Leiden in summer 2009, after years of irregular sightings along the Zuid-Holland coast, mostly in winter. It’s natal colony disappeared around 1988 and if the bird does breed, it must be somewhere else, possibly in Leiden. It’s regular appearances on a fish market in the city were used to document the progress of primary moult and to describe some weird feather loss on the head during post-nuptial moult.