This rough legged hawk is wintering in the same area as the dark morph. I have seen the 2 of them drive each other off a prime perch. I found this bird on a perch. I watched it jump and hover for a moment then it landed on the ground in a snowy field. The bird sat motionless for 3-4 minutes…them he pounced into a thicket of grass and pulled out a mouse. I’m guessing the bird knew the mouse was in there so the rough legged waited until the mouse peered out from the thicket of grass. Once the mouse appreared he became dinner. This shot is just after the bird finished the mouse meal.