Dutch Birding volume 33 (2011) no 1

Blue morph Ross's Goose on Schiermonnikoog in May 2009

On 9 May 2009, an unringed adult blue morph Ross' Goose Anser rossii was observed with Greylag Geese A anser and Dark-bellied Brent Geese Branta bernicla on Schiermonnikoog, Friesland, the Netherlands. The bird was photographed and seen by a handful of birders. It was accepted by the Dutch rarities committee (CDNA) as the sixth Ross's Goose for the Netherlands and the first blue morph. Blue morph individuals are extremely rare in this species, with a 'world population' of probably just over 100 birds (based on estimations that 'blue' birds represent 0.01% of the world population of more than 1.1 million birds in the early 21st century). With the continuing growth of the population, this number may now be higher. The CDNA concluded that the bird showed no visible hybrid influence and that there were no other obstacles to accept it as a presumed wild individual.

Martijn Bot, Leverkruid 12, 9801 LR Zuidhorn, Nederland
(m.botnoorderpoort.nl)