The White-winged Scoter is a large sea duck that breeds in the northern regions of North America and Asia. It winters further south along the Pacific and Atlantic coasts, where it can be observed diving for food. Here are some interesting facts about this distinctive waterfowl species:
Description
The White-winged Scoter is a stocky duck with bulky rounded body and large bill. The adult males are unmistakable during breeding plumage. They have entirely black bodies except for conspicuous white patches on their wings which give the species its name. Their bills also develop large, rounded knobs during the breeding season. Females are brownish-black and lack the bold white wing patch.
Size
The White-winged Scoter is one of the larger scoter species, with a length of 19-21 inches (48-53 cm) and wingspan around 32 inches (80 cm). Males weigh 2.3-3.2 lbs (1.1-1.5 kg) on average, slightly larger than females at 2.0-2.7 lbs (0.9-1.2 kg).
Distinctive Features
Some key features can help identify White-winged Scoters in the field:
- Thick orange or yellow-based bill with enlarged knob on males
- Conspicuous white wing patch visible in flight
- Entirely dark blackish body
- Bulkier and stockier profile compared to other scoter species
Breeding and Nesting
White-winged Scoters nest in the boreal forest regions of Alaska and northern Canada. They prefer wetland areas near shallow lakes and ponds surrounded by thick vegetation. The female makes a nest on the ground lined with down and vegetation. It is usually well-hidden in dense shrubs or brush close to water.
Courtship
In early spring, White-winged Scoters arrive at breeding areas and males begin courtship displays. They perform elaborate postures, bill gestures, and vocalizations to attract females. Groups of males may also swim rapidly together across the water during displays.
Clutch Size
Once paired, the female White-winged Scoter lays a clutch of 6-10 eggs. The eggs are pale olive or buff colored and oval shaped. She incubates them for about 30 days while the male leaves after mating.
Ducklings
The downy ducklings hatch and follow the female closely to water where they will learn to feed. They grow quickly and can fly at around 60-70 days. The mother protects and broods them on land while the father does not participate in rearing the young.
Migration and Wintering
White-winged Scoters undergo an extensive migration twice per year between their northern breeding areas and southern wintering habitat along the coasts. Their winter range extends along the Pacific coast from Alaska to Baja California, and along the Atlantic coast from Canada to Florida.
Fall Migration
In early autumn, White-winged Scoters gather in large flocks on lakes and bays prior to migration. They begin moving south by September and October, with peak migration in November. Males and females generally migrate separately.
Spring Migration
In March and April, the scoters start the journey back north towards their breeding grounds. They fly together in flocks and take routes along coastlines and across large lakes during migration. Males arrive at breeding lakes first to establish territories.
Wintering Habitat
On coastal wintering grounds, White-winged Scoters forage in shallow bays, estuaries and lakes. They feed heavily to build up fat reserves after the energetically demanding molt and migration. Large numbers concentrate along the Atlantic coast from the Gulf of St. Lawrence south to Long Island.
Diet and Feeding
White-winged Scoters feed mainly on mollusks, crustaceans, and other bottom-dwelling prey. Their large powerful bills allow them to consume sizeable mussels, clams, snails, and amphipods. They dive underwater to depths up to 60 feet while foraging.
Diving Adaptations
The White-winged Scoter has several adaptations that aid its diving ability:
- Streamlined body shape reduces drag underwater
- Thick plumage and dense down help maintain warmth and buoyancy
- Nictitating membrane covers eye while diving
- Large feet provide propulsion and steerage underwater
Prey Items
Some common foods eaten include:
- Mussels
- Clams
- Snails
- Shrimp
- Crayfish
- Aquatic insects
- Fish eggs
- Small fish
Feeding Flocks
White-winged Scoters forage in large dense flocks, sometimes numbering in the thousands of birds. Feeding groups include both males and females diving synchronously. They may also associate with other seaduck species while feeding and migrating.
Population and Conservation
The White-winged Scoter has a wide range and large total population estimated at 640,000 to 1.5 million birds. However, there are threats of concern for conservation of the species.
Population Status
Population trends:
Region | Population | Trend |
---|---|---|
North America | 640,000 | Stable |
Eastern Canada | 100,000 | Declining |
Western NA | 540,000 | Stable |
Threats
Some threats facing White-winged Scoter populations include:
- Oil pollution – oil spills affect wintering and migration areas
- Habitat loss – filling in of wetlands, human disturbance
- Overharvest – historically were overhunted, still hunted at sustainable levels
- Predation – nests subject to mammals like foxes, minks; ducklings taken by gulls
Conservation Efforts
Conservation actions aimed at protecting White-winged Scoter populations include:
- Monitoring and protection of key breeding and wintering sites
- Management of hunting limits and enforcement of regulations
- Restoration and preservation of wetland habitats
- Oil spill preparedness training to help rescue oiled birds
Interesting Behaviors
The White-winged Scoter exhibits some intriguing behaviors and traits that are unique among birds:
Dramatic Courtship Displays
Male scoters perform elaborate courtship rituals including bill-tossing, rapid head-shaking, body-shaking, and splash displays. Females incite males with neck-stretching and head-flicking movements.
Highly Social
White-winged Scoters travel together in large flocks during migration and while feeding and loafing in winter. Flocks may contain thousands of individuals at prime wintering grounds.
Molt Migration
Prior to the wing molt which renders them flightless, White-winged Scoters migrate up to 950 miles to specific molting sites around James Bay and the St. Lawrence estuary.
Nocturnal Foragers
On coastal wintering grounds, White-winged Scoters regularly feed nocturnally as well as during the day. Their adaptability allows them to take advantage of tidal cycles.
Significance to Humans
While not one of the most sought-after game ducks, the White-winged Scoter has some significance in terms of its ecological role and limited use by hunters:
Hunting
White-winged Scoters are legal game birds that have historically been hunted for food. Currently only moderate sport hunting occurs due to their somewhat undesirable meat and wariness. Annual harvest in the U.S. is around 40,000 birds.
Indicator Species
As seabirds feeding on shellfish, White-winged Scoters may indicate habitat quality and pollution levels when populations fluctuate or experience die-offs.
Ecosystem Roles
On breeding lakes, White-winged Scoters may impact fish populations by consuming eggs and young fish. On coastal wintering grounds, their intensive grazing can influence growth of bottom-dwelling invertebrates like mussels and clams.
Conclusion
In summary, the distinctive White-winged Scoter has many fascinating adaptations for its marine lifestyle. Careful management of the population and protection of breeding and wintering habitats will help ensure the survival of this unique sea duck. While not the most recognizable waterfowl species, the White-winged Scoter adds an element of biodiversity to northern wetland ecosystems.