These beautiful raptors are found across the American West during the summer months. They arrive in such numbers that they become almost more common than the ubiquitous Red Tailed Hawk. It is here that they will mate and have young before heading south to Argentina for the winter. Most of the females are now sitting on nests with eggs.
This particular one however has apparently not successfully mated yet although there was a male nearby and they undoubtedly are trying. Taken in Adams County, Colorado. For more about these birds, see here.