That this is an adult male common eider in eclipse plumage? Male eiders are very handsome sea ducks, who exhibit strong sexual dimorphism to attract females, so when I saw this mangy looking fellow feasting on a mollusk beside Capt. Joe & Sons, I didn’t know what it was. In the non-breeding season, they moult into this drab female-like appearance, which is called the eclipse plumage. When they shed feathers to go into eclipse, the ducks become flightless for a short period of time. Some duck species remain in eclipse for one to three months in the summer, while others retain the cryptic plumage until the next spring when they undergo another moult to return to their breeding plumage.