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Photo by Lynn Chamberlain
Photo Copyright Lynn Chamberlain
Ferruginous Hawk
Buteo regalis
NatureServe conservation status
Global (G-rank): G4
State (S-rank): S2
External links
Species range
The Ferruginous hawk, North America's largest buteo (Ng et al. 2017), breeds from south-central Canada to southern Utah and from eastern South Dakota to central Washington and Oregon. They winter from southern Wyoming to central Mexico and from the central southern plains to the Pacific Ocean (Olendorff 1993, Ng et al. 2017). While northern populations are often migratory, southern populations may be sedentary or migrate short distances. Ferruginous hawks are found year-round in Utah as breeders, migrants, and winter residents.
Habitat
Hayward et al. (1976) noted that in Utah this species is "found mainly in open desert country." Behle et al. (1985) reiterated this, saying that in Utah it resides "in lowland open desert terrain." Walters and Sorensen (1983) listed pinyon-juniper, barren cliffs and bluffs, sagebrush-rabbitbrush, and cold desert shrub (including saltbrush and greasewood) as habitats utilized by this species in Utah during the breeding season and noted that the species "forages widely in valleys".
Ecology
Ferruginous hawks are obligate grassland or shrub-steppe nesters (Jasikoff 1982, Olendorff 1993). In the Uintah Basin, they nest in low to mid-elevation, flat to gently rolling terrain with low-density shrub cover, good visibility, and abundant prey (Keough and Conover 2012). They will nest on the ground in open grasslands, but also use trees, pinnacles, or man-made structures (Ng et al. 2017). In Utah's cold desert regions, nests are commonly found in flat-topped junipers within open sagebrush plains, with pinnacles and outcroppings used in the northeastern and eastern parts of the state (DWR files). The juniper-sagebrush ecotone is crucial for nesting and foraging. Their primary prey is mammals, particularly rabbits, prairie dogs, and ground squirrels, but they also consume birds and reptiles (Olendorff 1993). Breeding success is linked to prey abundance (Woofinden and Murphy 1989). Wintering hawks often gather near agricultural fields and human settlements due to prey and roosting trees (Olendorff 1993).
Reproductive characteristics
In central Utah, the number of eggs hatching per nest ranges from 0.67 to 2.36 (Weston 1969). Fledging occurs on average around June 25, and rarely occurs after the first week of July.
Threats or limiting factors
Decreasing populations are commonly attributed to habitat loss, human disturbance, and a lack of secondary prey (Woofinden and Murphy 1989). Ferruginous hawks prefer wide-open habitats with good visibility and prey (Jasikoff 1982, Olendorff 1993). In Utah, these conditions are provided by lowland sagebrush, mountain sagebrush, and desert grassland, identified as Terrestrial Key Habitats in the Utah Wildlife Action Plan (Utah Wildlife Action Plan Core Team 2025). Droughts over the past two decades have threatened these habitats, leading to sagebrush die-offs, increased fire, invasive plants, habitat fragmentation, decreased plant vitality, and reduced prey populations. Ferruginous hawks are sensitive to disturbance, with flushing distances from nests impacting productivity based on approach, proximity, and frequency (Keeley & Bechard 2011). Disturbance impacts are increasing as human activities like grazing, resource extraction, and recreation expand in their habitats.
