Don Edwards San Francisco Bay National Wildlife Refuge

The Lesser Scaup (Aythya affinis) is a small North American diving duck that migrates south as far as Central America in winter. It is colloquially known as the Little Bluebill or Broadbill because of its distinctive blue bill. The origin of the name scaup may stem from the bird's preference for feeding on scalp – the Scottish word for clams, oysters, and mussels; however, some credit it to the female's discordant scaup call as the name's... less ↑

The Greater Scaup (Aythya marila), just Scaup in Europe, or colloquially "Bluebill" in North America for its bright blue bill, is a mid-sized diving duck though it is larger than the closely related Lesser Scaup. It is a circumpolar species, which means that its range circles one of Earth's poles. It spends the summer months breeding in Alaska, northern Canada, Siberia, and the northernmost reaches of Europe. During the winter, it migrates south down the coasts... less ↑

The Canvasback (Aythya valisineria) is a species of diving duck, the largest found in North America. It ranges from 48–56 centimetres (19–22 in) in length and weighs 862–1,588 grams (1.900–3.501 lb), with a wingspan of 79–89 centimetres (31–35 in). The Canvasback has a distinctive wedge-shaped head and long graceful neck. The adult male (drake) has a black bill, a chestnut red head and neck, a black breast, a grayish back, black rump, and a blackish brown tail. The drake's... less ↑