Swainson's hawk is common throughout the western United States. It is not a very large hawk. The males are 19 to 21 inches long, the female 19 to 22 inches long. The wingspan of the male is 47 to 51 inches, while the wingspan of the female is 47 to 57 inches. Notes- Reverse Sexual Dimorphism
Swainson's Hawk has two color phases. The adult light phase rather resembles the Red-Tailed Hawk. The plumage is white below and has a broad dark band covering the upper chest. The throat is white; the back, head, nape and wings are brown. The tail is brown also, and banded thouroughly with darker brown. The dark phase has 2 variants; the first is totally dark excluding the throat, which is white, or where the back is dark brown and the underside identical as it is in the light phase. Females and males are identical in plumages and are only identifiable by size. Notes- Color phases
The hawk builds a nest in a tree, anywhere from near ground level to 100 feet in the air. The nest is constructed of sticks and lined with leaves and grasses. 2 to 4 eggs are laid, dull white. They can be unspotted to heavily blotched with brown. The eggs are incubated for 4 to 6 weeks by both parents. Nestlings leave the nest 6 to 8 weeks later.
Swainson's Hawk prefers open country near forests; while it prefers to hunt in the prairie, it may nest in a bush if no trees are available. In flight, it is circles slowly and seemingly uncaringly. However, when prey is spotted the hawk turns into a swift and agile hunter, pursuing prey on the ground or catching insects on the wing. It will eat insects mostly, but also small mammals and other vertibrates.
Swainson's Hawk is found sketchily around the Alaska-Canada border. It is also found in southern Canada, throughout the Great Plains and western America, while staying clear of the western coast, south into central Mexico. It winters in South America and southern Florida.