Adult Plumage
Summer Plumage:
- A narrow black band on the forehead extends to the eyes, encompassing the area below and behind the eyes, and connecting to another band originating from the base of the beak.
- The lower neck and flanks are black.
- The head and upper neck are white with numerous faint black or reddish-brown streaks on the crown and nape, and fewer brown streaks on the neck.
- The back is black, with reddish-brown markings and black streaks down the center.
- The shoulders are reddish-brown and black with slightly white edges.
- The lower back is white.
- The rump and short undertail coverts are black, while the long undertail coverts are white.
- The tail is white on the basal three-quarters, with the terminal portion black and a white band at the tip.
- The wing coverts are pale brownish-black, with reddish-brown spots; the greater coverts have white edges.
- The primary flight feathers are brownish-black with white shafts.
- The secondary flight feathers are white at the base, with brown and reddish-brown tips.
- The belly is white.
Winter Plumage:
- The dorsal surface is dark brown, with each feather edged with a lighter color.
- The lower back, rump, and tail are similar to the summer plumage.
- The wing coverts are brown; the small and primary coverts have broad white markings at the tips.
- The front of the neck and flanks are brown, with each feather edged with a lighter color.
- Overall, compared to the summer plumage, the winter plumage has less white and more solid black and reddish-brown.
- Eyes are brown.
- The beak is black.
- The legs are orange-yellow.
Measurements:
- Wing: 141 – 155 mm
- Tail: 76 – 79 mm
- Tarsus: 24 – 27 mm
- Beak: 20 – 23 mm
Distribution:
This species nests in the Arctic regions of Europe and Asia; it migrates to Africa, India, Burma, Indochina, Malaya, and Sumatra during the winter.
Vietnam:
This species migrates through the coast of Thừa Thiên twice during September, October, and April.