Common Name
SWAINSON'S HAWK

Scientific Name
BUTEO SWAINSONI

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Photo by Jim Parrish
Photo Copyright Jim Parrish

Swainson's hawk, Buteo swainsoni, breeds in much of western North America, from the plains of south-central Canada to northern Mexico. All North American populations migrate south in winter, forming large flocks numbering in the thousands of individuals. Migratory routes avoid large water bodies, and flocks converge over Central America before continuing to foraging grounds primarily in Argentina. Migrating birds may travel more than 5,000 miles in two months. In Utah, this bird is found statewide, though primarily at mid-elevations in the western and northern parts of the state, in shrub and grassland habitats.

Whereas breeding birds feed chiefly on small vertebrate prey, especially ground squirrels, insects are the primary component of the diet during non-breeding periods. Nests are typically in solitary trees or bushes; in the West Desert of Utah, nests are often in junipers. Nests are constructed by both parents of sticks and lined with leafy twigs, grass, and weed stalks. Often nests are used for several years, or the old nests of other hawks or magpies are refurbished. Usually two or three eggs are laid in late spring. Incubation lasts 34 to 35 days, and the female does most of the incubating while the male provides food to the nest. Young are tended by both adults and leave the nest after 30 days. Young are capable of sustained flight after about 42 days, but are dependent on parents for food until they reach about two months of age.

Sources:

  • England, A. S., M. J. Bechard, and C. S. Houston. 1997. Swainson’s Hawk (Buteo swainsoni). Birds of North America 265: 28 pp.

  • Baicich, P. J., and C. J. O. Harrison. 1997. A guide to the nests, eggs, and nestlings of North American Birds, Second Ed. Academic Press, San Diego. 347 pp.

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