Large, powerful falcon. Inhabits a range of expansive habitats, from grasslands and mountainsides to open woodlands. Somewhat variable, but always dark "trousers" when perched; the tail extends beyond the wingtips at rest, giving it a “short-winged” appearance. Some birds can appear pale-headed due to light-colored crowns and sparsely-marked faces. In flight, the wings are broad, with dark underwing coverts. Adults have a thin “teardrop” eyeline, whereas juveniles have a thicker one. Compare to similar Gyrfalcon and Peregrine Falcon; note “trouser” color and consistently brown upperparts. Feeds on small mammals and birds.