The Northern or Hen Harrier is relatively long winged and long tailed.
Both female (brown) and male (grey) have a distinct white rump.
While holding its long wings in a shallow V in a low flight closely watching the land below, it hunts primarily small mammals and birds.
The adult male is sometimes nicknamed the "Grey Ghost", because of his striking plumage and owl-like facial appearance.
First 4 photos: Mesilla Valley Bosque State Park, Las Cruces, New Mexico, USA, 11 & 17 January 2019
Last photo: Bosque Del Apache National Wildlife Reserve, San Antonio, New Mexico, USA, 14 January 2019