greater scaup

The Greater Scaup (Aythya marila), also known colloquially as the 'bluebill' in North America, is a robust diving duck that belongs to the family Anatidae. This circumpolar species is known for its impressive migrations, traveling from the Arctic tundra to temperate coastal waters during the winter months.

The Greater Scaup typically measures between 40-51 cm in length. Adult males in breeding plumage exhibit a dark head with a distinct greenish sheen, a bright white flank, and a finely barred grey back. Females are more understated, featuring a brown body and a characteristic white patch at the base of their broad, bluish bill. Both sexes display a bold white wing stripe that is visible during flight.

During the breeding season, the Greater Scaup inhabits the Arctic and subarctic tundra, nesting near freshwater lakes and marshes. In the winter, they transition to more saline environments, frequently found in large coastal bays, estuaries, and occasionally on large inland lakes that remain ice-free.

As a proficient diver, the Greater Scaup feeds primarily on aquatic invertebrates. Their diet includes mollusks, crustaceans, and aquatic insects. During certain times of the year, they also supplement their nutrition with seeds and various parts of submerged aquatic plants.

Nesting usually occurs on the ground, often on islands or near the edges of tundra pools. The nest is a shallow depression lined with grass and thick down. A typical clutch consists of 6 to 11 olive-buff eggs, which the female incubates for approximately 24 to 28 days.

These birds are highly social and are often seen in large, dense groups called rafts, which can number in the thousands during the winter. They are powerful swimmers and divers, using their large feet to propel themselves deep underwater to forage for food along the bottom.

The Greater Scaup is currently listed as Least Concern by the IUCN. However, their populations are closely monitored due to threats such as habitat degradation, pollution in coastal wintering grounds, and the impacts of climate change on their Arctic breeding territories.

1. The Greater Scaup is the only diving duck found across the entire Northern Hemisphere.
2. It is very similar in appearance to the Lesser Scaup, but can be distinguished by its more rounded head shape and larger bill.
3. They are capable of diving to depths of up to 6 meters (20 feet) to reach their food.
4. In some regions, they are known as 'Broadbills' due to the width of their beak.

• Use a spotting scope: Because they often gather far out in coastal bays, a scope is essential for clear identification.
• Look for the head sheen: In good lighting, look for the green tint on the male's head to distinguish it from the purple tint of the Lesser Scaup.
• Check the wing stripe: If the bird flies, look for a white stripe that extends nearly to the wingtip; this is a key field mark for the Greater Scaup.

The Greater Scaup is a fascinating example of avian resilience, thriving in some of the most extreme environments on Earth. Whether you are observing them on a frozen Arctic lake or a windswept winter coast, they remain a highlight for birdwatchers and nature enthusiasts alike.