Periodic Status Review for the Ferruginous Hawk

The Ferruginous Hawk (Buteo regalis), was listed as state threatened by Department of Game policy in 1983, and in 1990 the Washington Wildlife Commission maintained the species on the state list of threatened species. North America’s largest buteo, the Ferruginous Hawk, occurs in low numbers in shrubsteppe and grassland regions of several eastern Washington counties, however, early accounts suggest they were once relatively abundant in the state. An average of 55 breeding pairs per year nested in the state between 1992 and 1995. More than 60% of the nesting territories are concentrated in Franklin and Benton counties, which are considered the core breeding range in the state.

The Ferruginous Hawk is largely restricted to grasslands and shrubsteppe. Conversion of native grasslands and arid shrublands to agriculture, urbanization, and the degradation of rangelands have contributed to the loss of nesting and foraging habitat on its breeding range in Washington. Degradation of fall and winter ranges frequented by Washington’s hawks in migration and the nonbreeding period has been documented through satellite monitoring. Reductions in prey base on the breeding range and depressed prey populations encountered during migration on fall and winter ranges are likely a significant factor in the decline of Washington’s breeding population of Ferruginous Hawks.

The breeding population of Ferruginous Hawks in Washington is in sustained decline. Between 1974 and 2016, there have been significant declines in nesting territory occupancy, nest success, and productivity. Additionally, the percentage of surveyed nesting territories supporting breeding pairs has significantly declined in the core breeding range of the species in Benton and Franklin counties. The distribution of breeding pairs statewide also appears to have contracted since the 1990s. There has been no improvement in habitat conditions or amelioration of primary threats, and therefore the recommendation is to reclassify the Ferruginous Hawk from threatened to endangered status in Washington.