Light-plumaged adult Swainson’s Hawks are distinctive because of the contrast on their chest and belly and also on their underwings. Darker birds and immatures can be tricky. Light adult Red-tailed Hawks have shorter, wider wings without the strong light-to-dark wing contrast and dark trailing edge of Swainson’s Hawk. Light Ferruginous Hawks typically are entirely light from breast to belly, and the wings are white from below. Rough-legged Hawks (even light adult males) have an obvious black-and-white tail pattern and their legs are feathered to the toes. Dark Red-tailed, Ferruginous, and Rough-legged hawks typically have dark wing linings and paler flight feathers, where dark-morph Swainson’s show either the opposite pattern or, rarely, entirely dark underwings. Immature Red-tailed, Ferruginous, and Rough-legged hawks also sport a translucent panel in the outer wing, unlike Swainson’s Hawk. The White-tailed Hawk of coastal Texas has an obviously white tail with a distinct black band. Immature White-taileds are mostly dark, but usually have a white patch on the chest, unlike Swainson’s.
Nearly all Swainson’s Hawks breeding in the eastern half of the range (east of the Rocky Mountains) are light in appearance. Darker-plumaged birds are more common in the West, although still in the minority, accounting for upwards of 10 percent of individuals.
Find This Bird
Your best bet for finding Swainson’s Hawks is during summer in open country west of the Mississippi River. They are perch conspicuously on utility poles, fence posts, and isolated trees in areas that otherwise lack such elevated perches. In perch-deprived areas, look for them standing on the ground in grassland or tilled agricultural fields. No other buteo species can be found in large numbers in such situations. During migration, they don’t move along ridgelines or lakeshores nearly as much as do other raptors. Instead, look for large flocks of soaring raptors over open country within their range, especially in April and September. If these are not Turkey Vultures, they are almost certainly Swainson's Hawks. At a few select migration spots including Hazel Bazemore Park (Corpus Christi, Texas) and a few sites in Middle America (Veracruz, Mexico; Kèköldie, Costa Rica; and Panama City, Panama) you can reliably see very large numbers of them passing south in fall. You can also see fairly large numbers in spring at the Santa Ana National Wildlife Refuge hawkwatch in south Texas.