Swainson´s Hawk

Exhibits a slender, elegant silhouette specifically adapted for high-endurance transcontinental flights, measuring between 17 to 22 inches (43 to 56 cm) in length with a wingspan ranging from 47 to 54 inches (120 to 137 cm). This diurnal raptor displays a complex color polymorphism, categorized into light and dark morphs. The light morph is characterized by a distinctive, dark reddish-brown chest patch or bib that sharply contrasts with a clean white throat and belly; in flight, its pale underwing coverts create a striking contrast with the dark flight feathers. Dark-plumaged individuals are almost entirely dark brown, though they still retain the contrasting paler undertail coverts. Its wings are uniquely pointed and narrow compared to other soaring hawks of the genus Buteo, allowing for efficient gliding over vast distances.

Geographical distribution: Undertakes one of the longest annual migrations of any North American raptor, traveling thousands of miles each year. During the spring and summer breeding season, it is distributed across the open plains of western North America, spanning from western Canada through the western United States down to northern Mexico. When the autumn migration begins, it embarks on an extraordinary journey of up to 12,000 miles (20,000 km) to its wintering grounds in the fertile Pampas of Argentina, with smaller numbers overwintering in parts of southern Brazil, Paraguay, and Uruguay.

Habitat: Primarily selects open landscapes characterized by low vegetation where thermals are abundant and visibility is high. It is a classic species of native grasslands, shrub-steppes, agricultural fields, prairies, and semi-arid savannas. It avoids dense forests and mountainous regions, favoring flat or gently rolling plains. On its South American wintering grounds, it is heavily associated with alfalfa fields, pastures, and agricultural land, where modern agricultural practices often disturb its insect prey.

Feeding: Demonstrates a highly opportunistic and seasonally flexible diet that shifts completely between its breeding and wintering ranges. In its northern breeding territories, it operates as a specialized carnivore, preying on small mammals such as ground squirrels, pocket gophers, and deer mice, alongside reptiles and amphibians. Conversely, during migration and throughout the wintering period in South America, its diet becomes almost exclusively insectivorous. It feeds voraciously on grasshoppers, locusts, and dragonflies, often foraging in large flocks on the ground, which has earned it the colloquial name "locust hawk."

Behavior: Highly gregarious outside the nesting season, a trait that sets it apart from many other solitary raptor species. During migration, thousands of individuals gather to form immense swirling flocks called "kettles", riding warm rising air currents to conserve energy. On their wintering grounds, these birds exhibit cooperative-like feeding behaviors, often following agricultural machinery to capture flushed insects or gathering in massive roosts on the ground or along utility lines near foraging fields.

Nesting: Establishes monogamous breeding pairs upon arriving at their northern nesting grounds in late spring. They construct a bulky, flat platform nest made of dry sticks and twigs, which they line with fresh green leaves, bark, and weeds to regulate humidity and temperature. These nests are typically positioned in solitary trees, windbreaks, riparian corridors, or occasionally on utility poles in open country. The female lays a clutch of 2 to 4 eggs, which are bluish-white with brown speckling. Incubation lasts for 28 to 35 days and is performed mostly by the female. The young are altricial and remain in the nest under parental care for approximately 40 to 45 days before fledging.

Conservation status: Classified as Least Concern (LC) on the IUCN Red List, reflecting its large global population and extensive distribution range. However, the species is highly vulnerable to localized threats along its migratory flyways. Historically, it suffered severe population declines due to organophosphate pesticide poisoning—specifically monocrotophos—used to control agricultural pests in its Argentinian wintering grounds during the 1990s. International conservation efforts and pesticide bans successfully mitigated this crisis, though habitat loss and wind energy development remain ongoing conservation concerns.