43 - 45.5 cm. 96 - 102 cm wingspan. 860 g. Large size. Bill dark, slender and the tip into a hook. Blackish cap (crown, nape and head) through level of eye. Upperparts grayish contrasting blackish M pattern. Upperwings with a striking, broad, whitish band from central flight feathers across of central coverts more external. Underparts white. Tail black. Legs pink. Males and females are similar.