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Breeding Range. (Fig.43). Fairly common in the southeastern half of the Missouri Coteau (within Dickey, McIntosh, Logan, Stutsman, Kidder, Burleigh, and Sheridan Counties and southeastern McLean County); uncommon in the northwestern half of the Missouri Coteau (in northeastern McLean County, and in Ward, Mountrail, Burke, and Divide Counties), in the southwestern portion of the Missouri Slope and southern portion of the Little Missouri Slope (in Adams, Bowman, Hettinger, and Slope Counties, southwestern Stark County, and southern Billings County), and in a restricted area that encompasses western Benson County, southern Pierce County, and northwestern Wells County; rare and local elsewhere--recent records along the James River valley near Ypsilanti, on the Arrowwood National Wildlife Refuge, in northeastern Foster County near Juanita, on the Souris Lake Plain in McHenry County, on the Coteau Slope in Burleigh, Logan, and McIntosh Counties, in the eastern portion of the Missouri Slope in Grant and Mercer Counties, and in the northern portion of the Little Missouri Slope in McKenzie County.

Early records during the late 1800's and early 1900's indicate that breeding populations on the Missouri Slope and Little Missouri Slope were much greater than at the present time. During the summer of 1873, Allen (1874) reported that this species, next to the American Kestrel, was the most common hawk along the expedition route from the Missouri River (near Fort Rice) west to the Montana line. In July 1874, it was recorded as abundant on the plains from Fort Lincoln southwest toward the Black Hills of South Dakota, and many nests were found (Grinnell 1875). On the Little Missouri badlands north of Dickinson, Ferruginous Hawks were considered to be quite common during the summer of 1918 (Gabrielson 1928).

During the late 1800's, large breeding populations of Ferruginous Hawks were also present on the Northeastern and Northwestern Drift Plains and in the northwestern portion of the Missouri Coteau. In May 1880, Capt. B. F. Goss recorded considerable numbers of this species on the Coteau hills in northwestern North Dakota and found four nests with eggs (Bendire 1892). During 1890-1896, it was recorded as a very common summer resident in Towner County, particularly in the hills in the northern part of the county (Judd 1917). The large numbers present in Benson County during the spring of 1896 are indicated by the fact that about 25 nests with eggs were found near Minnewaukan in a strip of land that measured a little over 40 miles in length and 8 to 15 miles in width (Rolfe 1896b). In 1897, many nests with eggs were also found on the hilly prairie country in the Devils Lake region (Rolfe 1898a).

Other early breeding records in northern and eastern portions of the state were reported as follows: eastern Stutsman County, 1880 (U.S. Nat. Museum specimen); Bottineau County, 1894 (A. Eastgate, in Friedmann 1963); Ramsey County, 1895 (Bryant 1895a); Nelson County, 1898 (Job 1898); Eddy County, 1902 (Bent 1907); Nelson County, 1912 (Bailey 1915b); Barnes County, 1912 (A. Eastgate); Ward County, 1913 (H. E. Peck and V. Bailey); eastern Walsh County, 1915 (Williams 1926); Ward County, 1915 (Woodruff 1923); Nelson County, 1920 (Wood 1923); and western Benson County, 1922 (P. B. Peabody, in Bent 1926).

Large numbers were still present in north-central North Dakota as late as 1929. At this time, Davy (1930) found this species to be very plentiful within the Mouse River loop, particularly in northern and western portions; a total of 21 nests with eggs were found in this area in 1929. More recent nests were recorded on the J. Clark Salyer National Wildlife Refuge in Bottineau and McHenry Counties in 1943 and 1948 (C. J. Henry).

Breeding Habitat. The Ferruginous Hawk, formerly called the "prairie eagle" or "eagle hawk" by Indians and the early settlers, personifies the vast, wild reaches of the original, rolling North Dakota prairie more than any other captor. Peabody (1905), in fact, even refers to North Dakota as "that ferruginous-rough-leg State". This magnificent bird together with the Sharp-tailed Grouse, Upland Plover, Burrowing Owl, Horned Lark, Sprague's Pipit, Western Meadowlark, Brown-headed Cowbird, Baird's Sparrow, Clay-colored sparrow, and Chestnut-collared Longspur comprise the key breeding species that characterize the avifauna of the mixed-grass prairie.

During the spring and early summer, breeding populations are largely restricted to areas that contain extensive expanses of native mixed-grass prairie. In the 1800's prior to the advent of agriculture, mixed-grass prairie was the preponderant habitat type throughout the greater part of North Dakota. At this time, breeding populations of the Ferruginous Hawk were very large and widely distributed. Unfortunately, since the late 1800's, the destruction of native prairie tracts through agricultural development has continued at a rapid rate up to the present time. As a consequence, the breeding populations are now confined to very limited areas, usually those with hilly terrain or with low-grade topsoil that have not been altered by the plow. Even many of these tracts have been reduced in quality for this species, owing to the effects of overgrazing.

Nesting. Breeding season: Mid-April to late July; peak, late April to early July. Extreme egg dates (43 nests): April 17 [1896] in Benson County (Rolfe 1896b) to June 7 [1901] in Nelson County (Bent 1901b). Extreme dates of nestlings (18 nests): May 27 [1943] in McHenry County (C. J. Henry) to July 16 [1974] in Foster County (RES). Records of dependent young out of the nest ranged from June 15 [1917] in Stutsman County (H. C. Oberholser) to July 27 [1913] in Williams County (V. Bailey).

Detailed descriptions of 61 nests indicate that about 45 percent were situated on the ground in native prairie, 29 percent were in trees, 12 percent were on large boulders or rock piles, 12 percent were on hay or straw stacks, and 2 percent (1 nest) was situated on the straw-covered roof of an abandoned stable. Another very unusual nest observed during June and July 1972 in Stutsman County was situated about 30 feet above the ground in a power transmission line tower (T. J. Dwyer, D. S. Gilmer). Most of the ground nests were located on boulder-strewn slopes near the crest of hills and ridges or on top of knolls. Tree nests were situated in isolated single trees, in small groves of trees, or in narrow woodland bands that bordered ponds, lakes, or streams. A considerable variety of tree species were utilized including cottonwood, quaking aspen, bur oak, peachleaf willow, American elm, and box elder. The height of 13 tree nests above the ground ranged from 10 to 45 feet and averaged 26 feet.

Considerable local variation in the relative use of various types of nesting sites was apparent. In the Devils Lake area, along the Sheyenne River to the south, and in Nelson and Steele Counties, trees in the heavier timber along streams were used as nesting sites (Bent 1901). The principal nesting sites in the Mouse River loop country included tall trees, low bushes, straw stacks, and rock piles, and, occasionally, nests were found on the ground (Davy 1930). In the vicinity of Minnewaukan in Benson County the species habitually nested in trees in some areas and on the ground of bleak, stone-covered hills in others (Rolfe 1896b). Nests were usually situated alongside large boulders on steep slopes of ravines in the Big Coulee area of southwestern Benson County (P. B. Peabody, in Bent 1926). Judd (1917) found that nests were situated on the ground on remote isolated hills in northern Towner County. In the Coteau hills of northwestern North Dakota, nests were found on the ground on rocky hillsides (B. F. Goss, in Bendire 1892). Larson (1928) reported that nests were located on cliffs of the badlands in northeastern McKenzie County. In southwestern North Dakota, many nests were found by Allen (1874) and Grinnell (1875); all of these were situated on the ground, usually near the summit of isolated buttes.

It would appear that there is a definite relationship between nesting sites and type of geological land forms. Nests on glacial ground moraine, lake plain, outwash plain, and deltaic sand were nearly all situated in trees, whereas nests on glacial dead-ice moraine, end moraine, Lames, eskers, and unglaciated bedrock formations were largely restricted to ground sites.

Indicated clutch size (35 nests): 3 to 6 eggs; mean, 3.9 eggs. In the Minnewaukan area of Benson County, Rolfe (1896b) reported that early sets often contained four eggs, although three eggs was the usual number for late sets. In the vicinity of Antler in Bottineau County, Davy (1930a) found that the greater number of sets contained four eggs, although five eggs was fairly common, and one record of six eggs was obtained.

Figure 43. Breeding Range of Ferruginous Hawk.

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Nestlings of Ferruginous Hawk. Billings County, June 1958 (photo by Ed Bry). Young of Ferruginous Hawk, shortly after leaving nest - about ten feet from nest. Stutsman County, July 1965 (photo by Robert E. Stewart).