"The common eider is called 'gammy bird' in Newfoundland for its habit of gathering in flocks for sociable quacking sessions. The name is related to the days of sail, when two ships falling in with each other at sea would back their yards and shout the news. The ship to windward would back her main yards and the one to leeward her foreyards for close maneuvering. This was gamming." --E. Annie Proulx, The Shipping News
"gam bird, gam drake, gammy bird. Common Eider: Gam-birds (from the social meeting of whalers at sea and because this species gathers in large flocks)." -- Dictionary of Newfoundland English, 2nd ed. Other nicknames include "Mobile goats, Witless Bay gammy birds, Bay Bulls bottle noses," quoted from the Book of Newfoundland.