More Waterfowl v6 previews... White-headed ducks have a highly fragmented distribution in the central and southwestern Palearctic, from south of Lake Baikal in the east, to northwestern Africa and the Iberian Peninsula in the west. Populations in north-central Asia are migratory, and spend the winter in the Middle East, Türkiye, and southeastern Europe. There are sedentary populations in Spain and northwestern Africa. Males have mostly white heads with blue bills. The White-headed duck is endangered with : 5,300 - 8,700 individuals left and a declining population trend. This duck became endangered due to a large reduction in populations in the last 10 years. Most of this decline is due to habitat loss and hunting, but interbreeding of the Spanish population with the introduced ruddy duck (Oxyura jamaicensis) is a more recent threat. This has led to the attempted eradication of the American species from western Europe.