Each autumn, an observation team atop the Bridgers counts raptors as part of an international effort to study these magnificent birds. Hawks, eagles, and falcons, sensing the shortening day, cooler weather, and less abundant prey migrate south. The Goshawk, Bald Eagle, and Golden Eagle may only be migrating a few hundred miles south. Long distance migrants such as the Osprey, Peregrine Falcon, or Swainson's Hawk may fly to Mexico or beyond. Many of the raptors seen have spent their summers in the eastern Rockies or Great Plains.
Most birds are juventiles, born just months ago.
The high mountains act as a funnel for raptors. Westerly winds produce updrafts along north-south ridges such as the Bridgers. By utilizing such terrain, a bird of prey can conserve energy for the long flight ahead. The Bridger site is but one site in a network of 10 sites in the west managed by HawkWatch International. Nationally, there are another two dozen sites devoted to counting these hunters of the sky.