Raptor Identification: Hawks, Falcons, Eagles, Vultures

A raptor is a bird of prey, and the fastest way to identify one is to decide its group before its species. The Peregrine Fund says scientists are still settling the exact definition, but lists three shared traits: keen vision, two to eight times better than a human's; a strong curved beak with sharp edges; and sharp talons used to catch prey.

Its worldwide list has nine groups: eagles, falcons, hawks, kites, osprey, owls, the secretarybird, seriemas and vultures. In North America, HawkWatch International's identification material covers 34 species of day-flying raptors in eight groups: buteos, accipiters, falcons, eagles, harriers, kites, osprey and vultures. Its full fact-sheet index runs to 43 species once owls are added. Owls have their own page here: owl identification.

• Buteos (Red-tailed, Red-shouldered, Broad-winged, Rough-legged Hawks): long broad wings and a relatively short tail. HawkWatch describes the Red-tailed Hawk soaring in wide circles on a slight dihedral and staying stable even in strong wind.
• Accipiters (Cooper's and Sharp-shinned Hawks): short wings rounded at the tips and a very long tail. They hunt birds by stealth through cover.
• Falcons (American Kestrel, Merlin, Peregrine, Prairie Falcon, Gyrfalcon): long pointed wings, a long tail and long primary feathers, as the National Park Service describes them.
• Eagles (Bald and Golden): huge. HawkWatch puts the Bald Eagle at twice the size of a Red-tailed Hawk, soaring on flat or slightly raised wings with a head that projects well forward.
• Harrier (Northern Harrier): flies low over fields with the wings in a shallow V, per the National Park Service.
• Kites: HawkWatch lists Mississippi, Swallow-tailed and White-tailed Kites in North America.
• Osprey: long, gull-like wings bent into an M when gliding, brilliant white underneath, and it plunges feet-first for fish (HawkWatch).
• Vultures (Turkey and Black): Turkey Vultures hold their wings in a strong dihedral, fly in a buoyant, wobbly way and show silvery flight feathers against black underparts (HawkWatch).

Audubon's advice for learning raptors in flight is to learn the Red-tailed Hawk thoroughly and judge everything else against it. HawkWatch's fact sheets give the measurements to do that with:

• American Kestrel: length about 10 in, wingspan about 22 in.
• Cooper's Hawk: length 14-19 in, wingspan 28-34 in.
• Red-tailed Hawk: length 17-22 in, wingspan 43-56 in.
• Osprey: length 21-26 in, wingspan 59-67 in.
• Turkey Vulture: length 24-28 in, wingspan 63-71 in.
• Bald Eagle: length 27-35 in, wingspan 71-96 in.

The ranges overlap, and a lone bird high overhead gives you nothing to compare it with, so treat size as a check on the group, not as the identification. Audubon also gives larger measurements for females than males in Red-tailed and Cooper's Hawks, which widens the ranges further.

Look at the wingtips. Falcons have long, pointed wings and long primary feathers; hawks in the buteo group have broad wings whose tips spread into separated fingers when soaring; accipiters have short wings with rounded tips.

Behavior helps too. The American Kestrel hovers over fields, and HawkWatch says it does so more adeptly than any other raptor; its wingbeats are quick and flickering. The Peregrine Falcon hunts by diving, and the National Park Service gives stoop speeds of up to 238 mph. A buteo, by contrast, usually hunts from a perch or soars in wide circles.

A jay-sized raptor on a roadside wire with orange upperparts is most likely a kestrel, which HawkWatch calls the smallest North American falcon. A bird that flaps several times and then glides between trees is an accipiter.

• Sharp-shinned vs Cooper's Hawk: Audubon calls it one of the hardest identifications. Cooper's is larger-headed, with the head projecting further in flight, a longer tail with a rounded tip when closed, and often a wider white tip. HawkWatch says it takes years of practice and some birds still cannot be identified.
• Osprey vs Bald Eagle: an Osprey shows an M-shaped wing and white underparts; an adult Bald Eagle is dark below with a white head and tail. HawkWatch notes Ospreys eat fish almost exclusively and rarely scavenge like eagles.
• Turkey Vulture vs eagle: at a distance both are large and dark. The vulture's small head, strong dihedral and wobbling flight separate it; an eagle soars steadily on flat wings.
• Young Bald Eagle vs Golden Eagle: HawkWatch says Bald Eagles take about five years to reach adult plumage, and juveniles are brownish overall with a dark bill and eyes. Its Bald Eagle sheet also notes that the Bald's head projects further forward than the similarly shaped Golden Eagle's.

More on flight shapes and tails is on the hawk identification in flight page, and the hawk identification page covers perched birds.

• HawkWatch International: species fact sheets on shape, flight, plumage, migration and distribution, a free mobile app with nearly 1,000 annotated photos and ID videos, and an Ask an Expert service for photos and videos.
• Merlin Bird ID: free, per NestWatch and The Nature Conservancy, and identifies birds from a description, a photo or a song.
• Google Lens: Google says it can search from your camera or an image and identify plants and animals.
• BirdLens: photograph the bird and it suggests the species. For raptors, a frame of the spread tail and one of the underwing make the result far easier to confirm.

Species differ entirely in Europe, Africa and Asia. Raptor Identification, a photo guide focused on European raptors, sorts its galleries by species, subspecies, sex, age and color variant, which is the right level of detail for eagles and vultures there.

Audubon's method for identifying birds of prey works in a fixed order, and each step narrows the next:

• Shape and size first. Put the bird in a group: Audubon describes buteos as large, broad-winged and short-tailed with spare, labored wingbeats; accipiters as small forest hunters flying with short, rapid bursts of flaps punctuated by a glide; falcons as slender and pointy-winged; and eagles and vultures as the largest and darkest, using their wings sparingly.
• Then color. Only within the group does plumage decide it. Audubon's example: an American Kestrel's overall paleness separates it from the slightly larger, darker female or young Merlin, even when you cannot see the face.
• Then motion. Audubon calls the kestrel's flight batty and flat, the Merlin's wingbeats fast, powerful and piston-like, and the Peregrine's shallow and elastic; in a glide, kestrels float and heavier Merlins sink.

Audubon's point is that a distant identification is built from several clues, not made in one look. The Wildlife Trusts use a similar three-way split for British birds: hawks and eagles (rounded or broad wings, tend to soar), falcons (tapered wings and tails, fast, often hover) and owls (rounded heads, forward-facing eyes, mainly nocturnal).

Audubon's online field guide gives a population estimate for each species. Ranked, the raptors covered on this site come out like this:

• Turkey Vulture: 28 million.
• American Kestrel: 9.2 million; Audubon calls it the most common falcon in North America, though numbers have declined since 1966.
• Great Horned Owl: 5.7 million.
• Red-tailed Hawk: 3.1 million.
• Red-shouldered Hawk: 1.9 million.
• Broad-winged Hawk: 1.9 million.
• Swainson's Hawk: 900,000.
• Rough-legged Hawk: 590,000.
• Bald Eagle: 200,000.
• Golden Eagle: 130,000.

So the bird of prey you are most likely to see overhead is a Turkey Vulture, and the one you are most likely to see perched by a road is a Red-tailed Hawk or, on a wire, a kestrel. An eagle is far less likely on numbers alone, which is worth remembering before calling a large dark soaring bird an eagle; check it against the Turkey Vulture first.

Readers in the UK are looking at a different list. The Wildlife Trusts' guide covers 14 species:

• Buzzard: the most frequently seen bird of prey; brown, with broad wings and a short tail, over grassland, farmland and woodland.
• Red Kite: large and reddish-brown, with an unmistakable forked tail and white wing patches; Wales and southeast England, and spreading.
• Sparrowhawk: the smallest UK raptor; males blue-gray above and white below, females brown, both with reddish cheeks; common in gardens.
• Kestrel: a small hovering falcon, gingery-brown above with a creamy spotted underside; males have a gray head and tail.
• Peregrine: the biggest British falcon, slate-gray above, white with black bars below, with a black mask.
• Hobby: a small slate-gray falcon with red "trousers" and a dark mask; southern and eastern heaths in summer.
• Merlin: the smallest British falcon, with blunt tail and compact, broad-based wings; moorland and coastal marsh.
• Hen Harrier and Marsh Harrier: the Hen Harrier is slim and medium-sized, and the female Hen Harrier shows a white rump, and the Marsh Harrier is the largest harrier, in reedbeds.
• Golden Eagle: very large, longer-winged and longer-tailed than a White-tailed Eagle, dark brown with a golden head; Scottish uplands.
• Osprey: dark above and white below with angled wings; wetlands in summer.
• Owls: Tawny, Barn and Short-eared, the last often hunting by day over moorland.

A large brown raptor soaring over farmland in Britain is most likely a Buzzard, and a forked tail means Red Kite.