This large buteo often hovers over fields, beating its broad wings in short rapid strokes much like a kingfisher or a kestrel. Rough-legged hawks often hunt at dusk. They dwell mainly in open country, fields and marshes. Harriers, also known as marsh hawks, have a white rump patch and a ruff of feathers around the face, much like the facial disks of owls. Immatures resemble females.
Marsh hawks inhabit fresh- or saltwater marshes, wet meadows, bogs and flat open farmland.
They prey on mice, insects, small birds and rabbits. The species tends to congregate in winter. Voice is a weak nasal pee, pee, pee. Marsh hawks nest on or near the ground, sometimes in fields and occasionally on a branch over the water. Nests are made of sticks, straw, grasses and are lined with feathers.