Gekleurringde, plaatstrouwe Zilvermeeuwen Larus argentatus op strandhoofden in Noord-Holland verliezen voedselbron?

Many Herring Gulls nesting at Texel (Wadden Sea) forage for mussels at any of 149 breakwaters along the mainland coast south of the colony. Arguably, the area is one of the prime feeding habitats for one of the largest colonies within The Netherlands. As a precautionary measure to be prepared for sea level rise as a result of global warming, the coastline need be strengthened and an operation is now due in which a significant part of this hard substrate will be covered in sand. Sightings of colour-ringed individuals, collected since 1986, show that many individuals are in fact very site faithful and a part of these birds will lose their favoured breakwater(s) and will have to look out for alternative opportunities. An intensified colour-ring programme has been launched to obtain more information on individual site fidelity in this major feeding ground, so that the effect of this ‘natural experiment’ can be evaluated with more precision. Observers are encouraged to collect more sightings data in the area and a list of ‘sites’ is provided to ensure the location of their observations can be pinpointed with the accuracy of individual breakwaters (Appendix 1).