Ferruginous Hawk - Habitat

Habitat

The preferred habitat for Ferruginous Hawks are the arid and semiarid grassland regions of North America. The countryside is open, level, or rolling prairies; foothills or middle elevation plateaus largely devoid of trees; and cultivated shelterbelts or riparian corridors. Rock outcrops, shallow canyons, and gullies may characterize some habitats. These hawks avoid high elevations, forest interiors, narrow canyons, and cliff areas.

During the breeding season, the preference is for grasslands, sage, and other arid shrub country. Nesting occurs in the open areas or in trees including cottonwoods, willows, and swamp oaks along waterways. Cultivated fields and modified grasslands are avoided during the breeding period. The density of Ferruginous Hawks in grasslands declines in an inverse relationship to the degree of cultivation of the grasslands. However, high densities have been reported in areas where nearly 80 percent of the grassland was under cultivation.

The winter habitat is similar to that used during the summer. However, cultivated areas are not necessarily avoided, particularly when the crops are not plowed under after harvest. The standing stubble provides habitat for the small-mammal prey base needed by Ferruginous and other hawks. One requisite of the habitat is perches such as poles, lone trees, knolls, rocky outcrops or large boulders. Ferruginous Hawks nest in trees if they are available, including riparian strips, but the presence of water does not appear to be critical to them.

The Ferruginous Hawk maintains minimum distances from other nesting raptors but will nest closer than necessary, suggesting that the distance is not fixed. The "nearest neighbor" distance has varied from less than 1 mile (1.6 km) to as much as 4 miles (6.4 km) with an average of 2 miles (3.2 km). Nests facing different hunting territories are tolerated much closer than nests facing the same hunting territory. The minimum distance between nests is probably about one half mile on densely-occupied areas. Nesting densities in several studies have varied from one pair per four to 2,450 square miles (10.4 to 6,346 square km). In Alberta, on one study site, there was a stable density of one pair per four square miles (10.4 square km), on average with little deviation from this mean. In Idaho, the average home range for four pairs of Ferruginous Hawk in the Snake River area was slightly over two square miles (5.2 square km).