Swainson’s Hawk – State Wildlife Action Plan

Swainson’s Hawk

Photo Credit: Tom Koerner, U.S. Fish and Wildlife Service

The Swainson’s Hawk (Buteo swainsoni) is a medium-sized broad-winged hawk of open habitats. They are long distance migrants, and individuals may migrate up to 10,000km to wintering habitat in Brazil, Paraguay, and Argentina. They exhibit polymorphism with distinctive dark and light color morphs also showing intermediate characteristics in between. Dark morph individuals are relatively uncommon, comprising an estimated 10 percent of the population. Dark morph plumage ranges in color from reddish-brown to a dark brown overall, with dark brown head, back, and upper wing. Light morph individuals have brown to grey upperparts, with a light belly and reddish-brown chest. In comparison to other species in the Buteo genus, Swainson’s Hawks have relatively long, narrow wings with noticeable tapering at the tips.

Overview

  • Species Common Name Swainson's Hawk
  • Species Scientific Name Buteo swainsoni
  • State Listing Status Sensitive

Ecoregions

Special needs

Swainson’s Hawks require open grassy and shrub-steppe habitats or agricultural areas for foraging, along with scattered shrubs or small trees for nesting. At Zumwalt Prairie in northeastern Oregon, prey species were most abundant in cultivated fields, making these areas important for foraging. Swainson’s Hawks are migratory, and do not winter in Oregon. They migrate to South America during the non-breeding season.

Limiting factors

The primary threat to Swainson’s Hawk populations on their breeding grounds is habitat loss. Habitats that Swainson’s Hawks use, including grassland and shrub-steppe habitats, are in steep decline in Oregon. Native grassland and shrub-steppe habitat has decreased dramatically as agriculture, urban and rural expansion, and renewable energy projects continue to expand. Swainson’s Hawk needs can be compatible with some types of agriculture: cultivated fields are often used as foraging habitats. Changes to natural fire regime, fueled by cheatgrass and fire suppression, add to habitat loss and changes in habitat quality. Poisoning with agricultural chemicals may be a significant source of mortality for Swainson’s Hawks on their wintering grounds. As a long-distance migrant, migratory connectivity is important and threats during migration and on wintering grounds, including collisions, habitat loss and degradation, limited prey availability, or persecution, can influence breeding population stability in Oregon.

Conservation actions

• Expand partnerships with private landowners and continue comprehensive conservation planning with federal land managers.
• Protect nest trees.
• Maintain shrub-steppe and herbaceous shrub habitat to promote a diversity of prey species.

Key reference or plan

Conservation Strategy for Landbirds in Sagebrush-Steppe and Riparian Habitats of Eastern OR and WA. Read here