The surf scoter (Melanitta perspicillata) is a large sea duck found along the coasts of North America. The adult males are black with white patches on the forehead and back of the neck. Immature males, also called subadults, resemble adult females but can be identified by their developing male plumage. Surf scoters feed by diving for mollusks, crustaceans, and other small invertebrates. They nest in the boreal forests of Canada and Alaska and migrate along the coasts to their wintering grounds.
Identification
Identifying immature male surf scoters can be tricky since they have an intermediate plumage between adult females and males. Here are some tips:
– Size – They are large, stocky ducks like adult scoters. Larger than a mallard.
– Bill – Their bill is swollen at the base and multi-colored with orange, yellow, white, and black unlike adult females.
– Head – They have a partial white patch on the nape and sides of the head. This is fading from juvenile plumage.
– Back – Scalloped black and white feathers on the back and upperwing coverts. This is the beginning of adult male plumage.
– Chest – They have a blotchy, molting chest without crisp black feathers. Light tan to white.
– Legs – Legs and feet are a reddish-orange color.
So in summary, immature males are larger than females, have a multi-colored bill, partial head patches, scalloped back feathers, blotchy chest, and orange legs. This combination helps distinguish them from both adult females and adult males.
Age
Surf scoters have a relatively long immature phase before reaching full adult plumage. The timeline is approximately:
– Hatching to 1 year – Juvenile plumage. Both sexes look similar to adult females.
– 1 to 2 years – Immature male plumage develops. Scalloped back feathers and head patches start to appear.
– 2 to 3 years – Near adult male plumage is acquired. May still have some female-like belly feathers.
– 3+ years – Full adult male plumage. Solid black body, white patches on head and back of neck.
So immature male scoters are usually between their first and third years of age. The scalloped black and white feathers on the back is a good indication you are seeing a 1 to 2 year old bird. They can start to resemble adult males in their second year but full plumage takes longer to fully develop.
Behavior
The behavior of immature males is similar to adults and subadults of both sexes.
– Foraging – They dive under water to feed on mollusks, crustaceans and aquatic invertebrates.
– Migration – They migrate along the Pacific and Atlantic coasts to and from their boreal forest breeding grounds.
– Social – They form large flocks during migration and wintering. Subadults may associate more with adult females.
– Vocalizations – They make typical duck quacks and vocalizations, though potentially at a higher pitch than adult males.
– Breeding – Immatures do not participate much in breeding activities. Adult males are territorial and attract females.
So in many respects, immature male scoters act like their adult counterparts. The main differences are their intermediate plumage and lack of breeding behavior. Their foraging, migratory and social habits are the same.
Range
The range of immature male surf scoters mirrors that of the overall species:
– Breeding – Boreal forest lakes and rivers in Alaska, Canada, and northeast U.S.
– Migration – Coastlines of North America from Alaska to Mexico.
– Wintering – Coastal waters, bays, and estuaries from Alaska to Baja California on the Pacific and Labrador to Florida on the Atlantic. Highest concentrations off British Columbia, Washington, Louisiana, and North Carolina.
Some key wintering and migration sites for seeing immature males include:
– Chesapeake Bay – Large numbers gather off Maryland and Virginia.
– Lake Erie – Great Lakes population winters here.
– Puget Sound – Main wintering area for Pacific birds.
– San Francisco Bay – Important migration stopover site in California.
– Long Island – New York beaches host winter flocks.
So immature scoter distribution follows the overall surf scoter range along the Pacific and Atlantic coasts. Look for them mixed in with flocks of adults at key migration hotspots and wintering areas.
Molting
The molting process is what allows immature male surf scoters to transition to their adult plumage. Here are some details:
– Timing – Primary molts occur from late summer to early fall after breeding season.
– Partial molts – Immatures may take several years with partial molts to acquire full adult plumage.
– Flight feather molt – Scoters lose all flight feathers at once, leaving them flightless for about 3-4 weeks.
– Body molt – Body feathers are lost gradually over several months.
– Nutrition – Molting is energetically demanding. Good food resources help ensure new feather growth.
– Hormones – Changes in testosterone and other hormones help trigger molt cycles.
– Emergence – Males emerge from molt with more white patches and scalloped feathers as subadults.
So the molting period is critically important for immature males to slowly transition to adult plumage. Their energetic demands are high as new feathers grow in. It is a delicate time in their life cycle.
Diet
Surf scoters feed on a variety of marine invertebrates obtained by diving:
– Mollusks – Mussels, clams, snails, scallops are favored foods.
– Crustaceans – Crabs, shrimp, amphipods, and other small crustaceans.
– Echinoderms – Sand dollars, sea urchins and other echinoderms.
– Worms – Polychaetes and marine worms.
– Aquatic insects – Larval and adult forms.
– Fish eggs – Especially from spawning herring and capelin.
Their short, powerful wings provide thrust for diving up to 60 feet to reach bottom-dwelling prey. Their thick bill is adapted for crushing shells of mollusks and crustaceans. Immature males have the same foraging behaviors and diet as adults. Good nutrition provides energy for migration and feather growth.
Threats and Conservation
Some key threats facing immature surf scoters include:
– Habitat loss – Coastal development, hydroelectric dams, water diversion. Loss of staging and wintering habitat.
– Overharvest of prey – Commercial mussel and shellfish operations can deplete food resources.
– Oil spills – Especially in concentrated wintering areas like the Gulf of Alaska.
– Human disturbance – Recreational activities near wintering flocks.
– Climate change – Rising sea levels, increasing storms, habitat shifts.
Conservation actions to help immature scoters include:
– Protect key habitats – Preserve wetlands, estuaries, staging areas along flyways.
– Limit coastal developments – Prevent disruption of sensitive coastal ecosystems.
– Regulate shellfish harvesting – Prevent overexploitation of mussel/clams.
– Oil spill prevention – Require double-hulled tankers, response plans.
– Manage human recreation – Limit disturbance to wintering flocks through zoning.
Providing protected wintering and migration habitats is crucial for immature surf scoters that are undergoing molt and acquiring adult plumage. Minimizing threats during this sensitive period will help maintain healthy populations.
Conclusion
In summary, immature male surf scoters have intermediate plumage between adult females and males as they mature:
– Identification focuses on emerging white head patches, scalloped back feathers, and multi-colored bill.
– They are subadults under 3 years old, reaching adult plumage by year 3.
– Behavior is similar to adults but immatures do not breed.
– Range covers coasts of North America over winter and migration.
– Molting enables the transition from female-like to male plumage.
– Diet consists of marine invertebrates obtained by diving.
– Conservation should focus on protecting key coastal and inland wetland habitats.
Understanding the development of immature male sea ducks provides insights into surf scoter life history and ecology. Identifying subadults also aids waterfowl surveys and management efforts throughout their annual cycle.