Recordleeftijd van Schoorlse Stormmeeuwen Larus canus

Between the late 1950s and 1977, thousands of Common Gulls were ringed as chicks in the colony in the dunes of Schoorl (Noord-Holland, The Netherlands). Recent observations have shown that Common Gulls from this colony reach a considerable age: it appeared that 12.1% of all gulls ringed as chicks were recovered at an age of over 15 years (544 recoveries up to and including 1990). Only 1.4% of Danish Common Gull recoveries were birds of such an age (1089 recoveries, Sorensen 1977). Three Common Gulls from the Schoorl colony were over 20 years old, while the oldest Danish bird was 19 years. In 1992 two Common Gulls were rediscovered in a newly established colony near Schoorl (4 km away from the ringing site) of an age of 21 years. In 1994 and 1995, time was spent to try and read rings of colonies in Schoorl. Two birds were found of an age of 24 years and 10 months, while the oldest Common Gull known to us from literature was 24 years and 2 months. A total of 11 over 20 years old Common Gulls were found, which, together with the earlier recoveries, mean that at least 16 of the Schoorl Common Gulls have reached an age of over 20 years. The question arises, whether this apparently exceptional longevity is connected to large-sacle breeding faileres due to Red Fox Vulpes vulpes predation and disturbance over the last decade in this particular mainland colony.