Adult Plumage:
Summer Plumage: Head dark brownish-black. Neck, belly, and tail white. Back and wings grayish-blue; primary feathers 2-5 white with black edges, forming black tips; primary feathers 6 and 7 gray with black tips; feather 8 gray with a black spot on the inner vane; subsequent feathers entirely gray. This form is rarely seen in Vietnam. Eyes brown or reddish-brown. Beak, eye-ring, and legs red.
Winter Plumage: Head and neck white with a dark gray-black stripe in front of the eye and another large stripe on the nape.
Juvenile Plumage:
- White plumage, with pale brownish-gray spots on the dorsal surface. White belly with a few reddish-brown streaks on the throat and chest. Primary feathers with large black markings. Tail feathers with black tips. Intermediate forms are frequently encountered. Beak yellow with a black tip. Legs pale yellow.
Measurements:
- Wing: (male): 295 – 340 mm, (female): 285 – 322 mm; Tail: 110 – 125 mm; Tarsus: 43 – 49 mm; Beak (male): 31 – 33 mm, (female): 29 – 33 mm.
Distribution:
The Common Goldeneye ( Bucephala clangula ) is distributed in temperate regions of Europe and Asia, Iceland, Kamchatka, and Sakhalin. During the winter, the species is found in Western and Central Europe, Africa, the Red Sea, Abyssinia, Mesopotamia, Iran, Baluchistan, India, Burma, Malaysia, Cambodia, Vietnam, China, Japan, and the Philippines.
In Vietnam, the Common Goldeneye is often observed in large river estuaries such as the Red River, Thai Binh River, Ma River, Ca River, and Cam Ranh Bay. Occasionally, this species is also seen in large lakes in the plains, such as West Lake in Hanoi.