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The most reliable field mark between White-tailed Hawk and Swainson's Hawk is the tail: White-tailed Hawk (all ages) shows a striking white tail with a narrow black subterminal band, while Swainson's Hawk (all morphs and ages) has a gray-brown tail with multiple narrow dark bands and a broader subterminal band. In flight, immature White-tailed Hawks have a boldly spotted black-and-white wing lining and lack the rusty shoulder patch of adults, whereas juvenile Swainson's Hawks show pale mottling in dark areas and a less obvious tail band. Adults are also separable by underpart and wing patterns, but beware of the variability in Swainson's Hawk morphs. Structure and jizz can help, but focus on tail and underwing pattern first, especially in flight.

1. Tail pattern is the single best mark: White-tailed Hawk (all ages) shows a white tail with a narrow black subterminal band; Swainson's Hawk always has a gray-brown tail with multiple narrow dark bands and a broader subterminal band. This is visible in flight and often when perched.
2. Rusty shoulder patch: Adult White-tailed Hawk has a conspicuous rusty-red shoulder patch when perched with wings closed. Swainson's Hawk never shows this feature, regardless of age or morph.
3. Underwing pattern in flight: Swainson's Hawk (light morph) has a unique two-toned underwing: pale leading edge (wing lining) and dark trailing flight feathers. White-tailed Hawk has a whitish underwing with indistinct brownish barring, lacking the sharp contrast of Swainson's.
4. Immature wing lining: Juvenile White-tailed Hawks have a boldly spotted black-and-white wing lining, which is lacking in Swainson's Hawk juveniles. Swainson's juveniles have pale mottling in dark areas but not the same bold spotting.
5. Underparts: Adult White-tailed Hawk is white below with faint barring, while Swainson's Hawk (light morph) is also white below but has a dark reddish "bib" across the chest and a white throat and face patch. Dark morph Swainson's are overall dark brown with a pale undertail, but still lack the white tail of White-tailed Hawk.
6. Rump color: White-tailed Hawk has a white rump, which can be visible in flight; Swainson's Hawk does not have a contrasting rump.
7. Upperparts: White-tailed Hawk is gray above; Swainson's Hawk is brown above. This is most useful when birds are perched or seen from above.
8. Size and structure: White-tailed Hawk is slightly larger and stockier, but this is subtle and not always reliable. Both are large, broad-winged hawks.
9. Flight style: White-tailed Hawk often hovers while hunting; Swainson's Hawk is more likely to soar with wings held in a shallow dihedral or to still-hunt from a perch.
10. Habitat context: In North America, Swainson's Hawk is more likely in agricultural areas and migrates in large flocks; White-tailed Hawk is more resident in tropical/subtropical grasslands and open scrub.
11. Juvenile confusion: Immature White-tailed Hawks can appear very dark, even nearly black in poor light, but always check for the white tail with a black band. Swainson's juveniles are paler below with mottling, and never show a white tail.
12. Shoulder patch absence in immatures: Immature White-tailed Hawks lack the rusty shoulder patch, so do not rely on this mark for young birds—use tail and wing lining instead.
13. Dark morph Swainson's Hawk: Even in dark morphs, the tail is banded, not white, and the underwing has a pale patch under the tail. White-tailed Hawk never shows this pattern.
14. Perched views: Look for the combination of white tail, gray upperparts, and rusty shoulder patch (adults) on White-tailed Hawk. Swainson's Hawk will be brown above, with a banded tail and no shoulder patch.
15. Seasonal context: Swainson's Hawk is migratory and may be seen in large flocks, especially during migration. White-tailed Hawk is more solitary or in pairs, and less likely to be seen in migration flocks.

Both species are large, broad-winged hawks with similar proportions. White-tailed Hawk is slightly larger and stockier than Swainson's Hawk, but the difference is subtle and not always reliable in the field. Swainson's Hawk has an average body mass of about 958.5 g [wikidata], while White-tailed Hawk averages slightly heavier (see detailed measurements in the notes), but overlap is considerable. Use size only as a supporting clue when birds are seen side by side.

• Immature/juvenile birds:
• White-tailed Hawk immatures are overall darker than adults, sometimes nearly black in poor light, and lack the rusty shoulder patch. Their wing lining is conspicuously spotted black-and-white, and the tail is brown with several dark bars, becoming greyer with a hazy band as they mature.
• Swainson's Hawk juveniles are paler below, with pale mottling in dark areas and dark mottling on the flanks. The chest is pale with some darker marks, and the tail has multiple narrow dark bands but the subterminal band is less obvious than in adults. No rusty shoulder patch or heavy black-and-white spotting on the wing lining.
• Adults:
• White-tailed Hawk adults are gray above, white below and on the rump, with faint pale grey or rufous barring. The tail is short, white, and has a narrow black band near the tip—very conspicuous in flight. The rusty-red shoulder patch is diagnostic when perched. Underwings are whitish with indistinct brownish barring.
• Swainson's Hawk adults (light morph) are white below with a dark reddish "bib" on the chest, a white throat and face patch, and brown upperparts. The underwings show pale linings and dark trailing flight feathers, forming a unique two-toned look. The tail is gray-brown with about six narrow dark bands and a broader subterminal band. Dark and rufous morphs exist, but all have banded tails, not white.
• Key contrasts: White-tailed Hawk always has a white tail with a single black band; Swainson's Hawk always has a banded gray-brown tail. Underwing pattern and shoulder patch are also strong clues.

Both species hunt from perches or by soaring over open country. White-tailed Hawk often hovers while hunting, whereas Swainson's Hawk is more likely to soar with wings in a dihedral or still-hunt from a perch. Swainson's Hawk is known for following tractors and fires to catch insects and small animals, and often perches or roosts on the ground during migration. White-tailed Hawk is more likely to be seen gliding or hovering over open habitats. Both can be opportunistic, but Swainson's Hawk is especially associated with grasshopper swarms and agricultural activity.

White-tailed Hawk is found in tropical and subtropical open habitats of the Americas, often in grasslands, savannas, or open scrub. Swainson's Hawk breeds in open country, grasslands, and agricultural areas, especially in western North America, and winters in South America. While both prefer open habitats, Swainson's Hawk is more closely tied to agricultural landscapes and migratory in much of its range, whereas White-tailed Hawk is more resident in tropical/subtropical zones.