Migration and Winter Ranges of Ferruginous Hawks From Washington Final Report -- October 2003
Between 1999 and 2003, 13 adult and 15 juvenile ferruginous hawks (Buteo regalis) from Washington were monitored via satellite telemetry to assess their migration, range use, and survival. These factors were studied to better understand ferruginous hawk ecology and population dynamics, and to promote recovery of this species from state Threatened status.

Migration and Winter Ranges of Ferruginous Hawks From Washington Progress Report -- January 2001
From 1999 01 we studied the migration and winter ranges of ferruginous hawks (Buteo regalis) that breed in Washington state. We attached satellite PTT’s (platform transmitter terminals) to 12 adult and 6 nestlings to monitor their long-range movements. Preliminary results from 7,120 locations showed most hawks migrated to the eastern front of the Rocky Mountains or the northern plains in the fall, and wintered in central or southern California. Ground reconnaissance at fall sites where adult hawks remained 4 to 10 weeks found hawks primarily associated with populations of Richardson’s ground squirrels (Spermophilus richardsoni) and pocket gophers (Thomomys spp.) in native prairie habitats or on edges of cultivated land. Three of 9 adult hawks (30%) were confirmed or suspected mortalities during the winter of 2000. In 2001 we deployed 4 PTTs on juvenile hawks to better understand their movements and survival. We plan to continue deployment of PTTs on juvenile hawks in 2002.

Migration and Winter Ranges of Ferruginous Hawks From Washington Progress Report -- January 2000
In the spring of 1999, a study was initiated to investigate the migration and winter ranges of ferruginous hawks (Buteo regalis) that breed in Washington state. We attached satellite PTT's (platform transmitter terminals) to 9 adults and 1 nestling to monitor their long-range movements. All but 1 adult migrated across the continental divide in early fall and most hawks became localized in northwestern Montana/southeastern Alberta. Adult hawks remained at initial destinations 4 to 10 weeks. Proximal cause of migration was a high population of Richardson's ground squirrels (Spermophilus richardsoni) along the northern Rocky Mountain front. Straight-line mean distance of migration to early fall destinations was 616 km. Hawks made at least 1 additional major movement prior to October. Three hawks migrated to the plains of North Dakota, Nebraska, and Oklahoma. Ground visits identified hawk locations in towns of black-tailed prairie dogs (Cynomys ludovicianus). Four adults migrated back across the continental divide to California. Ground visits identified these hawk locations in association with colonies of California ground squirrels (S. beecheyi). The juvenile hawk followed the same route of her mother, but moved back and forth along the migration path and covered at least 3,168 km in 69 days. We confirmed 1 adult mortality, possibly from gunshot, and another adult mortality was suspected. Satellite monitoring will continue through spring, 2000, with plans to deploy at least 4 additional PTTs.

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