Saturday, January 5, 2013

Scoters


 
Winter Visitors -- © Dave Spier

Having Lake Ontario along part of New York's northern border bestows certain wildlife advantages. A few deep water ducks, also referred to as "sea ducks," stop there for a winter vacation, rather than spending the energy on a longer flight to the Atlantic coast where many of their "friends" go. As cold as it may get, Lake Ontario’s influence moderates the local climate and keeps the shoreline milder than the duck's Canadian homeland.
 
White-winged Scoters, Melanitta fusca, cruise off shore and pull into the open water channels of several bays, including Sodus Point. One by one they dive under water, swim to the bottom and feed on mollusks, crustaceans, aquatic insects and a few plants that coat the rocks. Strong swimmers, they can dive to 40 feet. I don’t know if they eat zebra mussels, but the scoter's winter numbers are so low they’d have little impact even if they did.
 
This species also winters along the Pacific coast, based on the range map available at All About Birds. An interactive and zoomable range map is available on eBird. This version includes frequency data.


Male White-winged Scoters are black with a white "comma" or crescent under and behind the eye. When flying, they flash white wing patches (called speculums). At rest on the water, the white wing patches may be hidden or only show as a thin white line near the rear. The male’s bill is orange with a dark protuberance (knob) on top. Females are similar to males, but browner and have two lighter spots on the face and dark bills instead of orange. This species, the size of Mallards, is called the Velvet Scoter in Europe.
 
Two other slightly smaller species of scoters are rare in the Great Lakes. The Black Scoter male is all black with an orange bump on its bill, while the Surf Scoter male is all black with a multi-colored bill and two white patches, one on the forehead and a second on the nape (back of the head). The name scoter comes from their habit of scoting (scooting) through waves while feeding offshore.


Along Lake Ontario, White-winged Scoters can begin showing up in mid-October but many of these are gone by early November. They are probably passing through on the way to the seaboard. Our long-term winter residents arrive in December. By the end of March, these few scoters will be on their way back to the northern prairies and Western Canada, although a few migrants from the Atlantic coast may stop here again briefly in mid-April. Unlike Mallards which can jump into the air and fly, scoters need to get a running start across the water’s surface in order to get airborne. In migration, groups of scoters fly in long lines low over the water.
 
At one time White-winged Scoters nested across the width of Canada. Now they breed from Alaska to western Ontario province. The adult males leave the breeding grounds in July, while the females and young hang around for another three months. Are the males just self-centered and lazy, or do they reduce the competition for food by leaving early? Either way, look for them hanging around with the other winter ducks.
 
Corrections, comments and questions are always welcome at
northeastnaturalist@yahoo.com or connect through my Facebook page and photo page. Other nature and geology topics can be found on the parallel blogs Adirondack Naturalist and Heading Out. There's also a community-type page for The Northeast Naturalist.

No comments: