A fairly large hawk with a long tail, rounded wing tips, and a conspicuous pale eyebrow; adult has dark crown, blue-gray back, white underparts with dense gray barring, and conspicuous fluffy white undertail coverts; immature is brown above, buffy below, with dense blurry streaking, undertail coverts are dark-streaked, and tail has wavy dark bands bordered with white and a thin white tip; total length is 53-66 cm, with females averaging lager than males (NGS 1983).