Tripod or gunstock mount. Pens fail to work at low temperatures. In warm weather. Wings held in shallow dihedral. Also very falcon-like in shape, but more casual and buoyant in the air than larger falcons.
Light secondaries create pale line along trailing edge of wings on adults.
Head appears to stick as far forward as tail does behind. Northern Harrier Glides with shallow dihedral, flaps with deep, somewhat labored wingbeats. All plumages have light rump patch. Alternates flapping with short glides. Alternates flapping and gliding.