RESEARCH ON THE BLACK-HEADED GULL (Larus ridibundus) - Defects in colouring

Every year I am seeing some Black-headed gulls which are partially leucistic. Throughout the years I have captured 6 Black-headed gulls with a deviation in colour.

I have captured the first on December 4th 1997 in the Oosterpark in Amsterdam. This bird only has a metal ring and is read regularly until December 2012 in winters in- and near Amsterdam. Leucistic Black-headed gull. Amsterdam, December 2008. Ruud Altenburg.

The other five are colour ringed. Because these Black-headed gulls do stand out, the probability of observing them is higher. Two of these five were read abroad.

White E9KK was ringed on Dec 19th 2008 in Arnhem as a first calender year. This is a regular wintering gull in Arnhem. This bird has been read twice during migration! On Nov 22nd 2009 Rendsburg-Eckernforde, Schleswig-Holstein, GERMANY and on December 10th 2011 Svanedam, Nykobing Falster, DENMARK. Photo’s were made by Harvey van Diek, Arnhem, January 2010. Svanedam, Nykøbing Falster, Denemarken. December 10th 2011. Photo Kjeld Pedersen.

White LSB was ringed Jan 2nd 2007 Bijlmer, Amsterdam as a second calender year. This is a regular wintering gull of the Bijlmer and breeds in Finland. Photo below is made by Markku Kangasniemi te Tampere, Hame, FINLAND in April 2010. Photo’s below are from white LSB and are made by Maarten van Kleinwee. Amsterdam, Nederland in January 2011.