Hawk Identification in Flight: Shape, Tail, Underwing

From underneath, judge the wing outline first, the tail second and the pattern third. Audubon's guide to identifying raptors in flight sets out the same order: when birds are high or numerous, ground-level clues such as color stop working, and silhouette plus flight style carry the identification.

A broad cross in the sky, wings wide and tail short, is a buteo. A narrower cross with a long tail trailing behind is an accipiter. A shape like a swept-back arrowhead is a falcon. Only once the shape is settled does it pay to look at the belly band, the wrist patch or the tail bands.

• Soars in wide, slow circles with almost no flapping: buteo. Audubon describes the Red-tailed Hawk as a heavy bird that turns wide and slow.
• Flap, flap, flap, glide: accipiter, crossing a gap between trees.
• Rocks from side to side on a shallow V: Turkey Vulture. Audubon describes both the shallow V and the rocking.
• Quarters low over a field on a shallow V, showing a white rump: Northern Harrier.
• Hovers on fast wingbeats over grass: American Kestrel, which Audubon says hovers when there is no perch to watch from. A Rough-legged Hawk hovers too, but it is a far larger bird.
• Circles upward in a swirling flock: Broad-winged Hawks in a kettle, on migration.

Swainson's Hawk adds one more: it soars with the wings held above horizontal and the wingtips looking rather pointed, which separates it from other western buteos at a distance.

The tail is the most useful single part of a flying hawk, because it stays spread while the bird circles.

• Plain reddish-brown, no bands: adult Red-tailed Hawk.
• Narrow black and white bands, many of them: Red-shouldered Hawk, which also shows a pale crescent near the wingtip.
• Broad bands, few of them: adult Broad-winged Hawk. Juveniles have narrow bands with a thicker one at the end.
• White at the base, dark banding at the tip: Rough-legged Hawk.
• Whitish washed with rufous toward the tip: Ferruginous Hawk.
• Rounded tip with a wide white terminal band: Cooper's Hawk. Squared-off tip with a thin white band: Sharp-shinned Hawk.

A bird whose tail is longer than the width of one wing is an accipiter or a falcon, not a buteo, whatever the color.

Dark patch at the wrist. Rough-legged Hawk shows a blackish patch at the wrist of the wing standing out against paler flight feathers, and many birds also show a dark belly patch.

Two-toned underwing. Turkey Vulture has black wing linings against gray flight feathers, visible far beyond the distance at which the red head can be seen.

White linings against dark flight feathers. Light-morph Swainson's Hawk, with a narrow brown chest band between a white throat and a white belly.

Pale wing with dark tips and a dark trailing edge. Broad-winged Hawk.

Belly band. East of the Mississippi most Red-tailed Hawks show a white chest and a dark band of streaks across the belly, so a buteo with a clean belly in the East deserves a second look.

Autumn migration concentrates raptors along ridges and coastlines, and several species pass within an hour of each other, which is the fastest way to learn the shapes. Audubon's own advice is that a hawkwatch gives you the repetition. Broad-winged Hawks in particular migrate in kettles, and Audubon notes that thousands can be seen along ridges, coastlines or lake shores when the wind conditions are right.

Bring the camera. A burst of frames through one full turn will usually catch the spread tail, the head projection and the underwing, and those three together settle almost every common species.

The red tail that gives the species its name belongs to adults only. HawkWatch describes adults with a red tail, with or without multiple black bands, and juveniles with a brownish tail crossed by narrow dark bands. From below, Audubon notes, the tail is whitish and the red only shows through when the bird flies overhead, so a hawk circling high above can look pale-tailed.

The body marks that go with it, from HawkWatch's fact sheet:

• Patagial marks: dark marks on the leading edge of the underwing on typical light birds.
• Belly band: a band of streaks across the belly; eastern birds have lightly marked underwings and often a whitish throat.
• Western light birds: heavily marked underwings and belly, broad patagial bars and a darkish throat.
• Dark morph: about 15% of western birds.
• Krider's: strikingly pale, with a mostly white head and tail and very faint patagial marks.
• Harlan's: the most variable form, from ghostly white to completely black below; Audubon notes a whitish tail with dark marbling.

Shape holds across all of them: long broad wings, a relatively short tail, and wide circles on a slight dihedral. HawkWatch gives 17-22 in for length and 43-56 in for wingspan.

These two overlap in length, so size alone will not separate them. Shape, tail and behavior will.

• Wings and tail: Cooper's has short wings rounded at the tips and a very long tail; Red-tailed has long broad wings and a short tail (HawkWatch).
• Tail: Cooper's tail is banded, rounded at the tip when closed, often with a wide white tip (Audubon); an adult Red-tailed's is red, with or without several black bands (HawkWatch).
• Adult plumage: Cooper's is blue-gray above with a blackish cap and rufous barring on white below; Red-tailed in the East has a white chest and a streaked belly band.
• Eye: HawkWatch says a Cooper's eye changes from yellow-green to yellow-orange by the first spring and to dark red in adults.
• Hunting: Cooper's hunts birds by stealth, moving from perch to perch in cover, and is the hawk that raids feeders; Red-tailed hunts from a high perch over open ground.
• Size: HawkWatch gives Cooper's 14-19 in with a 28-34 in wingspan, and Red-tailed 17-22 in with a 43-56 in wingspan. The wingspan gap is the useful part.

• Turkey Vulture: large and dark, soaring in circles. It holds its wings in a strong dihedral and wobbles in flight, with a small bare red head (HawkWatch).
• Osprey: hawk-shaped but with long, gull-like wings bent into an M, and white underneath. It hunts fish over water.
• Falcons: a kestrel on a wire or a Peregrine on a building. Long pointed wings rather than broad or rounded ones.
• Blue Jay: heard, not seen. Audubon says one of its calls is almost identical to the scream of a Red-shouldered Hawk and the calls of a Broad-winged Hawk, so a hawk call from a tree full of jays may not be a hawk.

The raptor identification page sorts all of these into their groups.

Not rare at all. Audubon describes the Red-tailed Hawk as widespread and common, estimates the population at about 3.1 million, and says numbers are stable or still increasing. It lives in almost any terrain with some open ground for hunting and some high perches, from woodland with clearings to grassland and desert, which is why people see it on highway light poles and fence posts.

If you see a large hawk perched in the open beside a road in North America, Red-tailed is the first species to check.

The Hawk Migration Association of North America (HMANA) guide to hawks seen in North America gives the underside marks of the larger birds that get mistaken for hawks, and of the hawks this page has not yet covered:

• Northern Goshawk: 18-24 in, larger than a crow and heavy-bodied, with a pale underbody and prominent white undertail coverts.
• Ferruginous Hawk: the largest buteo, eagle-like at 20-26 in, pale below with dark leggings and a mostly white tail.
• Osprey: eagle-sized with a clean white body and black wrist marks, gliding with a kink, an M shape, in its long narrow wings.
• Bald Eagle: long flat wings with a straight leading edge, and a head that sticks out about as far as the tail. Immatures vary in how much white they show, but HMANA says white on the wing linings is surely a Bald Eagle.
• Golden Eagle: like a large buteo with curved wings and a slight dihedral; its head protrudes much less than its tail.
• Turkey Vulture: dark wing linings with light flight feathers, a small head, a long tail and a sharp dihedral.
• Black Vulture: white patches at the wingtips, wings held flat, stiff wingbeats, and a shorter tail and wings than a Turkey Vulture.

HMANA also notes that many hawks differ with age and between light and dark forms, especially in the West, so its guide shows only the adult of the most common form.

From below, an adult Cooper's Hawk shows rusty underparts, short rounded wings and a long tail with a rounded tip. HMANA gives 14-19 in, near the size of a crow, with stiff wingbeats.

The Sharp-shinned Hawk has the same rusty underparts and shape, so check three things:

• Tail tip: rounded on Cooper's; square or notched on Sharp-shinned (HMANA).
• Size: Cooper's is near crow size; Sharp-shinned is 9-13 in, near jay size (HMANA).
• Wingbeats: stiff on Cooper's; floppy on Sharp-shinned (HMANA).

A lone bird high overhead gives you nothing to compare its size with, so the tail tip is usually the mark that decides it.

The word buzzard means different birds on each side of the Atlantic. Wikipedia notes that in parts of the United States the Turkey Vulture is commonly called a 'turkey buzzard', while in Britain and the Old World buzzard means a hawk of the genus Buteo, the same group as the Red-tailed Hawk.

So in North America the question is usually hawk or vulture, and the underside settles it:

• Turkey Vulture: two-toned underwing, dark linings and light flight feathers, a small head, a long tail and wings in a sharp V that rock in flight.
• Black Vulture: white patches only near the wingtips, flat wings and stiff wingbeats (HMANA).
• Red-tailed Hawk: light breast, a streaked belly band and a dark leading edge to the wing, with wings held in only a shallow dihedral (HMANA).

HMANA's silhouettes answer this in one look. Falcons are streamlined, with long pointed wings, a long tapered tail and strong rowing wingbeats. Accipiters have short, wide, rounded wings and a long tail. Buteos have broad wings and a broad rounded tail and soar in wide circles.

From underneath, a Peregrine shows a light breast and throat and flies with quick, powerful wingbeats; a Merlin is dark and heavily streaked below with a banded tail; an American Kestrel is light underneath, jay-sized and buoyant (HMANA). Audubon separates the Merlin from the similar-sized Sharp-shinned Hawk by its pointed wingtips.

An eagle in flight looks bigger and heavier, with long straight wings held flat; a hawk has more rounded wings and may hold them in a shallow V. The Colorado State Publications Library, drawing on the Colorado State Parks raptor monitoring handbook, describes eagle wings as straighter, sometimes called plank-like, and hawks as stocky with short, broad, rounded tails.

The size gap is large. Audubon gives the Red-tailed Hawk a wingspan of 45-52 in and the Bald Eagle 6 ft 8 in; the Golden Eagle is about 6 ft 6 in and, per Audubon, soars on long broad wings held flat.

Two checks settle most cases:

• Head: a Bald Eagle's head sticks out well in front of the wings. Audubon says a young Golden Eagle looks a bit longer-tailed and smaller-headed than a young Bald Eagle.
• White patches on a dark eagle: Audubon says a young Golden Eagle has a white patch in the center of the wing and a white tail base, while a young Bald Eagle shows at least some white mottling on the body or wing linings. Bald Eagles take about 5.5 years to get the white head and tail (Audubon).

If the big dark bird rocks from side to side on wings raised in a V, it is neither: Audubon describes the Turkey Vulture soaring with wings held in a shallow V and a two-toned underwing.

When many raptors pass at a distance, Audubon's introduction to raptors in flight says colors and field marks become useless and you have to rely on silhouette and flight pattern. Its practical tips:

• Learn the Red-tailed Hawk first. Its rounded wings look muscular, thick and bulging, and it soars in wide, slow turns, flapping hard only when it has to. Judge every other raptor against it.
• Sharp-shinned vs Cooper's: the Sharp-shinned's small head sits in a valley between its wings, while the Cooper's larger head projects in front of the leading edge. Sharpies fly energetically; Cooper's soar more.
• American Kestrel: wandering, playful flight; Audubon's separate raptor article calls it batty and flat, and says kestrels float in a glide.
• Merlin: flies with purpose and does not wander, with fast, piston-like wingbeats; heavier Merlins sink in a glide.
• Peregrine: the largest of the three, broad-chested with extra-long wings and tail, crossing the sky like a jet, with shallow, elastic wingbeats.

Audubon recommends visiting a hawkwatch in migration season, where the repetition of seeing hundreds of birds is what builds this skill.

For British birds, The Wildlife Trusts give these flight clues:

• Buzzard: broad wings and a short tail; the most frequently seen raptor.
• Red Kite: forked tail and white wing patches, unmistakable once the tail is seen.
• Kestrel: hovers; falcons in general have tapered wings and tails and are fast and agile.
• Merlin: blunt tail and compact, broad-based wings.
• Golden Eagle: longer wings and a longer tail than a White-tailed Eagle.
• Osprey: dark above, white below, with angled wings showing dark patches.
• Hen Harrier: slim; the female shows a white rump.

A small falcon hovering over a roadside verge is most likely a Kestrel, the hovering falcon in the Wildlife Trusts guide; a soaring brown bird with a notched or forked tail is a Red Kite, not a Buzzard.