몸길이는 수컷 33.5㎝, 암컷 35㎝, 날개 길이 72∼84㎝ 몸 윗면은 흑갈색이며, 아랫배와 아랫꼬리덮깃, 넓적다리 깃털은 붉은색이다.
The body length is 33.5cm for males, 35cm for females and wings in 72~84cm. The upper side of the body is dark brown, and the lower belly, lower tail coverts, and thigh feathers are red.