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Platte River Status: A common migrant and fairly common and widely-distributed breeding species. Tout (1947) observed Swainson's hawk commonly in Lincoln County during 11 May to 21 October, but failed to find a nest. Rosche (1979) found Swainson's hawk in the lower North Platte River Valley during 23 April to 11 September.

Breeding Range: A fairly common breeding species in the Platte River Valley west from Buffalo County, and in the Sandhills. Uncommon and very local in the eastern half of the Platte River Valley, on the Eastern Plain, and Dissected Plain. Short (1961) found Swainson's hawk breeding as far east as Silver Creek, Merrick County, where he found a nest with two young.

Breeding Population: The population in 1979-1980 was estimated at 250 breeding pairs.

Habitat: We recorded Swainson's hawk only in upland prairie where the mean nesting density was <0.2 pairs per km². In the Platte River Valley, most nests are located in single trees, or open shelterbelts adjacent to grasslands or wet prairie. Most nesting pairs on a central North Dakota study area were associated with shelterbelts and adjacent cropland or upland prairie (Faanes 1982). Faanes (1983) found Swainson's hawk fairly common on native prairie tracts that contained scattered woodlands in western North Dakota.

Effect of Habitat Alteration: The conversion of native grasslands to agricultural production has produced a negative impact on this species, primarily through a reduction of the prey base. Some positive impacts have been derived from tree plantings, especially in the Sandhills where plantings are used for nest sites.

Nesting Data: We have located 6 active nests in the study area during 3 May to 2 June. Two nests with adults incubating were observed near the Mormon Island Crane Meadows, Hall County, on 27 May 1978. Wycoff (1956) described a nest located in a plum tree in native prairie 16 km north of Lexington, Dawson County, that contained young on 30 June 1956. Jones (1939) found young Swainson's hawks in a nest near Hastings, Adams County in 1939. Extreme egg dates in North Dakota extend from 29 April to 15 July (Stewart 1975).