The first Eiders (Somateria mollissima) this spring were seen on Ölfusá River by Selfoss on April 4. The Eider usually keeps to the sea and breeds in dense colonies not far from the shore. It breeds by Öflusá River all the way up to Sog River which is the furthest from the sea that it breeds (20 km). The Eider is the most common duck in Iceland, the breeding population counting around 300,000 pairs. The male is black and white and the female is brown.