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Greater Scaup
The Greater Scaup (*Aythya marila*) is a medium-sized diving duck known for its distinctive rounded head and striking black and white plumage in males. It plays a crucial role in aquatic ecosystems, primarily feeding on mollusks and aquatic plants, thus influencing benthic communities. While not holding significant cultural importance in many regions, it is a popular species among birdwatchers and is a game bird in some areas, subject to hunting regulations.
42-51 cm
Length
71-80 cm
Wingspan
Least Concern
Conservation Status
Distribution
The Greater Scaup has a circumpolar distribution, breeding in the Arctic regions of North America, Europe, and Asia. It migrates south for the winter, inhabiting coastal areas and large inland lakes in temperate zones across North America, Europe, and eastern Asia. The migration routes are extensive, often covering thousands of kilometers.
Lifespan
The average lifespan in the wild is not well documented but is estimated to be around 5-10 years, with some individuals living longer. Captive individuals may live longer.
Greater Scaup's Habitat
Habitat Types
Coastal bays, Estuaries, Large inland lakes, Tundra ponds (during breeding season), Reservoirs
Climate Zones
Arctic, Subarctic, Temperate
Adaptations
Greater Scaup are adapted to cold, aquatic environments. Their dense, waterproof plumage provides insulation, and their webbed feet are efficient for underwater propulsion. They also possess a specialized bill structure for filtering food from the water and sediment.
Variations
Two subspecies are generally recognized: *A. m. marila* (Eurasian) and *A. m. nearctica* (North American). The North American subspecies is slightly larger, but visual differences are subtle.
Appearance
Breeding Plumage
Breeding males have a glossy black head, neck, breast, and rear, contrasting with white flanks and a pale gray back. Females are brown with a distinctive white patch at the base of the bill. Non-breeding males (eclipse plumage) resemble females but retain some darker features.
Seasonal Feather Changes
Males undergo a complete molt after breeding, acquiring the eclipse plumage. They regain their breeding plumage in the fall.
Sex Based Plumage Differences
Significant sexual dimorphism exists, with males displaying much brighter and contrasting plumage during the breeding season.
Notable Features
Rounded head shape, Yellow eyes, Broad, bluish-gray bill with a small black nail at the tip, White patch at the base of the bill in females
Diet and Feeding
Primary Foods
Mollusks (clams, mussels), Aquatic invertebrates (crustaceans, insects), Aquatic plants (seeds, roots, tubers), Small fish (occasionally)
Foraging Behavior
Greater Scaup are diving ducks, typically foraging in relatively shallow water (usually less than 6 meters deep). They dive to the bottom and feed on benthic organisms, using their bills to filter food from the mud and water.
Specializations
Their bill is adapted for efficiently straining small food items from the substrate. Their diving ability allows them to access food sources unavailable to surface-feeding ducks.
Seasonal Diet Variations
Diet varies seasonally and regionally depending on food availability. During the breeding season, they may consume more insects and crustaceans. In winter, mollusks often form a larger part of their diet.
Behavior
Social Structure
Greater Scaup are highly gregarious, especially during migration and winter, forming large flocks often numbering in the thousands. During the breeding season, they are more dispersed, forming pairs or small groups.
Communication
Soft, purring calls by males during courtship, Harsh 'scaup' calls (giving them their name), Visual displays (head movements, wing flapping)
Migration
Greater Scaup undertake long-distance migrations between breeding and wintering grounds. They often fly at high altitudes and may travel non-stop for considerable distances. Migration is triggered by changes in day length and weather conditions.
Territorial or Group Behaviors
Males defend a small territory around the female during the early breeding season. Outside of the breeding season, they are not territorial and form large flocks.
Conservation
Threats
Habitat loss and degradation (wetland drainage, pollution), Climate change (affecting breeding grounds and food availability), Oil spills, Hunting (in some regions), Lead poisoning (from ingestion of spent lead shot), Exposure to contaminants (e.g., heavy metals, pesticides)
Protection Programs
Wetland conservation and restoration efforts, Hunting regulations (bag limits, season lengths), Monitoring programs (tracking population trends), International agreements (e.g., Migratory Bird Treaty Act)
Local National Laws
Protected under various national and international laws, including the Migratory Bird Treaty Act in North America and similar legislation in Europe and Asia.
Population Trend
Decreasing
Population Estimates
The global population is estimated to be between 2.8 and 3.5 million individuals, but significant declines have been observed in some regions, particularly in North America.
Interesting Facts
Greater Scaup can dive to depths of over 20 feet.
Although they typically feed in shallower water, their diving ability allows them to exploit a wider range of food resources.
They are one of the latest ducks to migrate south in the fall.
Their tolerance for cold temperatures allows them to remain on their breeding grounds longer than many other duck species.
Flocks of Greater Scaup can sometimes be so large that they appear as dark clouds on the horizon.
This gregarious behavior is particularly evident during migration and on their wintering grounds.
Greater Scaup are known to hybridize with Lesser Scaup.
Although they are distinct species, occasional hybridization occurs where their ranges overlap.
Faqs about Greater Scaup
How can I tell the difference between a Greater Scaup and a Lesser Scaup?
Greater Scaup are slightly larger and have a more rounded head, while Lesser Scaup have a peaked head. The nail on the bill is smaller on the Greater Scaup. In good light, the male Greater Scaup's head has a green sheen, while the Lesser often shows purple.
Where can I see Greater Scaup?
During the winter, look for them on coastal bays, estuaries, and large inland lakes. During the breeding season, they are found in the Arctic and subarctic regions.
Are Greater Scaup endangered?
Greater Scaup are currently listed as Least Concern by the IUCN, but their populations have been declining in some areas, raising concerns about their long-term conservation status.
Do Greater Scaup mate for life?
Greater Scaup generally form new pair bonds each breeding season, and do not mate for life.
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