Dutch Birding volume 28 (2006) no 5

Aberrant Grey Heron near Capelle aan den IJssel in July-August 2006

From 22 July into August 2006, an aberrant first-year Grey Heron Ardea cinerea stayed for c two weeks at Capelle aan den IJssel, Zuid-Holland, the Netherlands. It was much darker in plumage than a normal Grey Heron and had a strongly decurved bill. This combination gave the impression of a hybrid Grey Heron x Glossy Ibis Plegadis falcinellus but this is a most unlikely hybrid type that has not (yet) been documented. More likely, it was a rare combination of an aberrant plumage and bill deformation. There have been previous records of unusually dark Grey Herons but not in combination with a deformed bill. The combination of deformed bill and melanism is sometimes observed in other species, such as (domesticated) Mallard Anas platyrynchos.

Enno B Ebels, Joseph Haydnlaan 4, 3533 AE Utrecht, Nederland
(ebelswxs.nl)
Willem van Rijswijk, Schalkeroord 315, 3079 WG Rotterdam, Nederland
(wsvanrijswijktiscali.nl)