The harrier is a slim hawk with narrow wings and a long, slender tail, providing it with maneuverability and agility. Harrier is from the Old English word hergian, and means to harass, ravage, or plunder. This bird has also been called a marsh hawk because it inhabits open marshlands and wet meadows. In Idaho, northern harriers are associated with deserts, marshes and irrigated agriculture; they avoid forested areas. They are year round residents of Southeast Idaho
The Northern Harrier is one of the most widespread and easily recognized hawks of North America. It is a graceful hawk who hunts by deliberately criss-crossing back and forth an area, flying just 10 to 30 feet above the ground. It hunts in a cruise-listen-pounce technique. It courses across the terrain with a series of slow, deep and regular wingbeats. The downstroke of each beat ends with a distinct snap. The steady wingbeats are interspersed with short, sailing glides. During the glide the wings are held stiffly above the body in a dihedral (V-shape). Its slow pace enables it to drop down instantly onto its prey as soon he spots it and grab the prey with its sharp talons.
The harrier’s diet is composed of mostly rodents such as voles and mice. It is, however, a versatile and opportunistic hunter. It can take small birds in flight or snatch them from cover with its long legs like an accipiter. It can pounce on frogs, small snakes and insects from a hover. It can hunt by sitting motionless and watching like a red-tailed hawk. It can finish off wounded waterfowl and eat carrion in the manner of a bald eagle. In fact, it could be said that whatever is seasonally available is the harrier's favorite prey.
Unusual among hawks, Northern Harriers use their sense of hearing to help locate prey. They have an owl-like facial disk to help with directional hearing and soft feathers for a quieter flight.
These are the only hawk-like bird known to practice polygyny - one male mates with several females. The male Northern Harrier attracts a female with a roller-coaster display flight, often performing 25 rises and falls. Northern harriers usually return to the same area to nest each year. They make a pile of sticks and grass for a nest on the ground, often near low shrubs or in tall clumps of vegetation. When incubating eggs, the female sits on the nest while the male hunts and brings food to her and the chicks. Young hawks fledge 4 – 5 ½ weeks after hatching.