While volunteering at the Poda Nature Conservation Centre near Burgas/Bulgaria in summer 2008, an aberrant Black-winged Stilt / Stelzenläufer (Himantopus himantopus) was among the most striking birds around. According to the nomenclature of van Grouw, it’s a „brown“ (not albino, leucistic etc. – kindly confirmed by A. Zedler who also wrote a paper on this topic, see here). In this mutation („probably the most common one in birds“), the number of (eumelanin) pigment granules is not reduced, but their synthesis is incomplete – feather parts that are normally black, are brown in affected birds.