Adult Plumage:
The dorsal plumage is brown, with each feather edged in rufous or rufous-brown. The sides of the head and neck are rufous or rufous-brown, with black feather shafts. A dark brown or blackish band extends from the gape. The area in front of the eyes is white with downy black feathers. The tail is dark brown, lightly tinged with rufous or brown, with the tips of the feathers edged in a lighter color. The outer tail feathers are paler than the central tail feathers. The primary flight feathers are pale black with gray edges; the inner vane of each feather, from the notch inwards, is white with brown barring, becoming gradually rufous on the outermost feathers. The chin is pale rufous with faint black streaks.
The throat and upper breast are rufous or rufous-brown, sometimes with rufous-brown feather edges and black feather shafts. The lower breast and belly are white with brown streaks and barring. The thighs are dark brown, occasionally with white barring. The Japanese subspecies may have a darker plumage; in this phase, the plumage is generally dark brown or mahogany-brown, with the feathers on the head often tinged with rufous. The ears are rufous, and the area in front of the eyes and the forehead are white. The tail feathers show indistinct barring.
Juvenile Plumage:
The dorsal plumage is pale brown, with each feather broadly edged in white or pale rufous-brown; the feather bases are white or have white barring, especially on the inner vane. The area in front of the eyes, forehead, and eyebrow are white or pale rufous-brown. The belly is white, pale rufous-brown or rufous, with the breast, flanks, and sometimes the belly having dark brown streaks. The thighs are brown or pale rufous, with pale white or rufous-brown barring. The undertail coverts are pure white. The tail is paler than in adults and tinged with rufous, with approximately 12 transverse bars, of which the 6 outermost bars are quite distinct; the other bars are incomplete and indistinct. The eyes are brown. The beak is brownish-gray, with a slightly paler base. The skin at the base of the beak is yellow. The legs are yellow.
Measurements:
- Wing (male): 374 – 410 mm, (female): 380 – 454 mm
- Tail (male): 198 – 209 mm, (female): 225 – 248 mm
- Tarsus (male): 63 – 65 mm, (female): 69 – 74 mm
- Beak: 29 – 36 mm
Distribution:
This species is distributed in Japan, Korea, North China, and eastern Russia. In winter, they migrate south to India, Burma, South China, Indochina, and Malaysia.
This species has been recorded in Vietnam in Bắc Cạn and Khánh Hòa.