A large falcon with short tail; 35-51 cm TL; 410-1600 g; Sexes are different in size; female larger. Head and neck: Forehead light grey; crown and nape grey; black mark (moustache) on front of cheek; eye dark brown; skin around eye yellow; cere yellow; bill grey with black tip; throat white.
Body: Overall dark grey; feathers with barred with grey tips; breast and abdomen white with black bars.
Limbs and tail: Legs and feet yellow; tail grey with black bars, black tip.