It has been four years since i captured an adult Whooper Swan (Cygnus cygnus) on the Kierskie Lake (Poznan). Recently seen there again after two years of lack of information. It has a very interesting life history so far:
winter 2008 - Kierskie Lake and month after went to Belarus winter 2009 - Denmark winter 2012 - again Kierskie Lake
As You can see, it has been observed only in winter time. Propably it is breeding on the east of Europe.