In the late summer, when the fields are cut and the grass is golden, the northern harriers soar over the mown areas, looking for mice, voles, and other small mammals. They fly smoothly, in long distinctive swoops; they can hold their position in the wind by hovering as they watch for movement in the grass. Harriers are our year-round hawk, hunting the open fields and pastures in all weather.
Besides their distinctive flight patterns, northern harriers are easy to spot because they have a white rump. Rough-legged hawks have a similar white streak at the base of the tail and hunt over open areas, but it has broader wings and a shorter tail, and shows white at the base of the underside of the tail. So if you can see the white from below, it's a rough-legged; if it is summer, it's probably a harrier. Besides, their flight patterns are different; the rough-legged doesn't hover and swoop the exhilerating way a harrier does.