Circus hudsonius, commonly known as the Northern Harrier, is native to North America. Its geographical distribution extends across Canada and the United States, primarily throughout the northern and western regions of the continent. During the non-breeding season, its range extends to Central America, including the northern parts of Mexico.

The Northern Harrier typically inhabits open landscapes, including wetlands, marshes, grasslands, tundra, and prairies. These environments are characterized by their open, treeless areas which facilitate the bird's ground-hunting behavior. The climate across its habitat range is varied, encompassing temperate and subtropical zones, with distinct seasonal variations affecting temperature and precipitation.

As a bird of prey, the Northern Harrier occupies an ecological niche as a hunter of small mammals, birds, and insects. It has adapted to hunting by flying low over open fields or marshes, using its keen sense of hearing to locate prey. This hunting technique is supported by its unique facial disc, which helps focus sound to its ears, similar to owls. The species' adaptation to marshlands and grasslands allows it to avoid competition with other raptors that may inhabit forested regions.