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Swainson’s Hawks, Buteo swainsoni

Swainson's hawk perched on a log in a forest

Swainson’s Hawks breed in North America and migrate to South America for the winter. They have a wide breeding range that extends from western North America, including western Canada, down to the southwestern United States. During the non-breeding season, they migrate to the pampas of Argentina and other parts of South America. They inhabit open habitats such as grasslands, prairies, agricultural fields, and savannas.

Swainson’s Hawks are medium-sized raptors. Adults have a striking appearance with a mix of dark and light colors. The upperparts are dark brown, while the underparts are mostly white with fine streaking or rufous barring on the chest and belly. The leading edges of the wings also have white patches, called “patagial marks,” which are visible in flight. The tail is long and squared off at the tip, with a dark band at the end. The base of the tail may appear whitish when viewed from below.

During their breeding season, Swainson’s Hawks are often seen soaring in the skies, using thermal air currents to effortlessly glide and search for prey. They are known for their impressive aerial acrobatics.

Swainson’s Hawks primarily feed on small mammals, particularly rodents like mice, voles, and ground squirrels. They also consume insects, birds, reptiles, and amphibians. They employ various hunting techniques, including soaring, hovering, and perch-hunting. While soaring, they scan the ground for prey and use their keen vision to locate prey. Sometimes multiple individuals work together to flush out prey from vegetation.

Swainson’s Hawks build large nests in tall trees or on man-made structures such as utility poles. They often choose solitary trees or those near the edges of woodlands. The nests are constructed with tree branches and twigs, lined with softer materials like grasses, leaves, and bark strips. Both male and female participate in nest building.

Females lay 2 to 4 eggs, each at intervals of about 2 to 3 days. Incubation lasts around 30 to 35 days and is primarily performed by the female. The male assists in incubation and provides food during this period. After hatching, both parents participate in raising and feeding the young. The chicks are fed a diet of small mammals and other prey items brought by their parents. The parents tear the food into small pieces to feed their young until they are able to consume larger prey.

The fledging period for Swainson’s Hawks occurs approximately 5 to 6 weeks after hatching. The young hawks leave the nest and start to explore nearby branches, strengthening their flight muscles and honing their hunting skills. The parents continue to provide food and guidance during this period.

Swainson’s Hawks are known for their remarkable long-distance migrations. They undertake a challenging journey from North America to South America, covering thousands of miles, as they follow favorable wind patterns and thermal currents.