Scoters are big black sea ducks, fairly common in coastal Alaska. They congregate in large flocks in the spring, sometimes numbering thousands of birds, before they migrate to freshwater marshes in interior and northern Alaska and Canada to nest.
Scoters' wings make a whistling sound as they fly. These big ducks don't leap into flight like mallards, they need some "runway" space on the water to get going, and their wings slap against the surface as they gain the speed to get fully airborne. Once aloft they are powerful fliers and cover hundreds of miles in just a few days during migration.
Scoters feed on mussels and other shellfish, including small crabs. The scoter's gizzard is like a powerful fist that crushes mussels and grinds up the shells. This organ can crush a clamshell that would require a hammer for us to break open. Scoters in a flock dive in sequence like falling dominoes. Within a few seconds, as if cued by some secret signal, dozens or even hundreds of ducks plunge beneath the water. In a large flock, one edge dives first, and row after row of ducks disappears. About 20 or 30 seconds later, they pop up, and in the course of five or 10 seconds the entire flock reappears.
There are three kinds of scoters - surf scoters, white winged scoters and black scoters. All are similar at a glance - large black ducks generally in big flocks. Those flocks may contain a mix of the three species.
Scoters are commonly called coots on the East Coast, and surf scoters are known as skunk-head coots because of the black and white markings (These are not to be confused with the "real" coot, a duck-like bird in the rail family). Back east, white-winged scoters form winter flocks numbering tens of thousands of birds; a raft of 180,000 scoters was counted off Long Island, New York, on a December day in 1952.