Also known as the Marsh Hawk or Hen Harrier.
Body Length: 17-24 in.
Weight: 12-18 oz.
Wingspan: 3.5-4.5 ft.
Adult males are slate or bluish gray in color with a white belly. Adult females are brown with a buff-streaked chest. Both have a white rump patch. Both are brown the 1st year. Harriers have large ear openings and an owl-like face with a facial disk enabling the Harrier to find prey in dense grasses and marshes. They have soft feathers for quieter flight.
Breeding Northern Harriers are most common in large, undisturbed tracts of wetlands and grasslands with low, thick vegetation. They breed in freshwater and brackish marshes, lightly grazed meadows, old fields, tundra, dry upland prairies, drained marshlands, high-desert shrubsteppe, and riverside woodlands across Canada and the northern United States. Western populations tend to breed in dry upland habitats, while northeastern and Midwestern populations tend to breed in wetlands. During winter they use a range of habitats with low vegetation, including deserts, coastal sand dunes, pasturelands, croplands, dry plains, grasslands, old fields, estuaries, open floodplains, and marshes.
Their favorite food is small mammals, birds, insects, and reptiles. They hunt low over grasslands, marshes, and wetlands. They have been known to drown waterfowl. Harriers hunt by flying slow and low to the ground, quartering and tilting their head side to side listening for prey.
Harriers are ground nesters and ground roosters and can be polygynous with a single male mating with possibly 2-3 or more females. The male courtship display is dramatic consisiting of dives, barrel rolls, flipping upside down and coming out of it to go back up. Male provides food for femaleand young by aerial dropping food to the female.
These are the only hawk-like bird known to practice polygyny – one male mates with several females. When incubating eggs, the female sits on the nest while the male hunts and brings food to her and the chicks. Up to five females have been known to mate with one male in a season. A male will maintain a territory averaging 2.6 km2 (1.0 sq mi), though male territories have ranged from 1.7 to 150 km2 (0.66 to 57.92 sq mi). The eggs are incubated mostly by the female for 31 to 32 days. The male will help feed chicks after they hatch, but doesn't usually watch them for a greater period of time than around 5 minutes. The male usually passes off food to the female, which she then feeds to the young, although later the female will capture food and simply drop into the nest for her nestlings to eat. The chicks fledge at around 36 days old, though breeding maturity isn't reached until 2 years in females and 3 years in males. Wikipedia.
Harriers are communal roosters during the winter and sometimes seen with the Short-Eared owl (it's counterpart at night).
Juvenile males have pale greenish-yellow eyes, while juvenile females have dark chocolate brown eyes. The eye color of both sexes changes gradually to lemon yellow by the time they reach adulthood.
Northern Harrier fossils dating from 11,000 to 40,000 years ago have been unearthed in northern Mexico.