Vierde broedgeval van de Zeearend Haliaeetus albicilla in Nederland

The only pair of White-tailed Eagles in The Netherlands nested again in the Oostvaardersplassen. Half a metre of nesting material was added on top of the 2008- structure, but the diameter largely remained the same. The nest is built in a Salix sp., and stands at a height of 8.7 m above ground level (in a flooded part of the marsh). On 14 May 2009, when the nest was visited for ringing purposes and the collection of prey remains, an unhatched egg was found together with a single chick. Based on back-calculation from the estimated age of the chick (using measurements taken during ringing, when the male chick was c. 38 days old), laying was estimated to have commenced on 28 February. Compared to 2006, the year that the pair settled and attempted breeding for the first time, egg laying has shifted forwards for almost a month (26 March vs. 28 February). This is in line with the increasing age of the breeding pair (female in 2009 in her 7th calender-year, the male even older but of unknown age). Prey remains found on the nest involved Coot Fulica atra (11), Greylag Geese Anser anser (2) and Carp Cyprinus carpio (2). A similar diet was found in previous years, and reflects prey species in high abundance in the Oostvaardersplassen. The fruits of colour-ringing (which started in 2007; in 2006 the chick was not ringed) were finally reaped in 2009 when four observations became available, scattered from 25, 85 and 125 km (within The Netherlands, twice involving the female chick ringed in 2007 and once one of the 2008-chicks) to 380 km (Schleswig-Holstein, Scharsee, the male ringed as a chick in 2008). The latter site is an important area for immature, non-breeding White-tailed Eagles.