An adult northern harrier is 17 to 24 inches long. This hawk has a narrow body and wings and a long tail. There is a white-feathered patch at the base of the tail. The body of the male has gray feathers while the female has brown-and-cream, streaked feathers. The underside of the wing has a dark tip.
The northern harrier is a common migrant and uncommon winter and summer resident in Illinois. It winters in Central and South America. The northern harrier lives in marshes or fields. This bird eats amphibians, birds, insects, mammals and reptiles. It flies near the ground, gliding over an open field or marsh looking for food. The wings form a shallow "V" during flight. While migrating, the northern harrier flies alone. Its call is "pee, pee, pee." Spring migration begins in late February. Nesting occurs from May through July. The nest is built on the ground and is made of twigs and grasses. Two to five blue-white eggs are laid. Fall migrants begin appearing in July.