Adult Male:
Summer plumage: The summer plumage exhibits considerable color variation. The nape and the anterior part of the neck have long, puffed ornamental feathers. The eyebrows, breast feathers, and feathers on the wings display varied colors: white, pale rufous, yellowish-rufous, dark brown, mahogany brown, black, black-green, blue-black, or red-black. These feathers may also feature streaks or patterns of different colors. The white belly has black streaks. The bare skin around the eyes, the base of the beak, and the legs also exhibit varying colors.
Adult Female:
Smaller in size. The summer plumage also shows varied colors, but less striking than the male. The back and the upper tail are dark. The tail feathers and the secondary wing feathers are nearly monochromatic: pale black-brown. The underside of the tail is white.
Winter Plumage:
In winter, both males and females have similar plumage. The dorsal surface is gray-brown. Feathers on the head, neck, back, and wing coverts are pale brown, edged with white. The tail is gray-brown, with the central feathers darker and edged with a lighter color. The belly is pale rufous-brown. The throat, belly, and under-tail coverts are white.
Eyes are brown. The beak is pale black. Legs are pale gray-green or yellow-green.
Measurements:
Wing (male): 173 – 190 mm, (female): 150 – 166 mm; Tail (male): 78 – 79 mm, (female): 64 – 70 mm; Tarsus (male): 46 – 50 mm, (female): 41 – 44 mm; Beak (male): 30 – 36 mm, (female): 29 – 31 mm.
Distribution:
This species nests in northern Europe and Asia; it migrates south for the winter to Africa, India, Myanmar, and Indochina. In Vietnam, this species is found in the South during the winter.