Identifying Silhouettes

By Jerry Liguori
Photos by Jerry & Sherry Liguori

One of the most challenging tasks in hawk watching is to identify a raptor by its silhouette. For me, most birds that I fail to identify are ones silhouetted in poor light due to cloud cover or their proximity to the sun. Attempting hawk identification under these conditions can be humbling but also fun and rewarding. All birds possess a unique shape -- even telling songbirds in flight from their silhouette is possible. I have seen birders such as David Sibley (author of The Sibley Guide to Birds) consistently separate warbler species in flight. Similarly, I've heard Pete Dunne (co-author of Hawks in Flight) exclaim "Peregrine!" from what seemed like miles away. However, even the most dedicated birders cannot name every bird they see. But with practice, patience, and desire, anyone can distinguish most hawks based on shape alone.

Some birds stump all hawk watchers from time to time, especially the Northern Harrier or "great fooler." When viewed while hunting low over a field or marsh, the harrier is easily identified by its tipsy, buoyant flight, exaggerated dihedral, and white "rump" patch. But when viewed on migration, the harrier takes on various shapes as it employs different flight strategies. I have mistaken harriers for Peregrine Falcons, Northern Goshawks, Cooper's Hawks, Red-tailed Hawks, Swainson's Hawks, Rough-legged Hawks, Golden Eagles, and Turkey Vultures. How can one species be confused with so many others?

Notice Something Unfamiliar

Most birds' shapes vary radically in each distinct posture such as head-on, gliding, soaring, and wing-on. When gliding overhead with wings pulled in and tail
folded, even buteos and accipiters can appear pointed-winged like a falcon. However a falcon's "hands" or primaries extend well beyond the trailing edge of its wings, whereas most buteos and accipiters do not. The harrier possesses long, narrow wings and a long, narrow tail and often appears very falcon-like in a glide (Figure 1). Take time to study each hawk overhead. Noticing something unfamiliar or recognizing what a bird is not, is an important step in the identification process. Birds approaching head-on can be particularly tough to identify. Long-winged hawks may appear stocky or vice versa. Many raptors have different body shapes and hold their wings in a unique manner relative to their body, creating a distinct silhouette. Studying these nuances helps greatly in the identification of hawks from this tricky angle.

Separating the silhouettes of extremely similar species such as the Sharp-shinned Hawk (Figure 2) and the Cooper's Hawk (Figure 3) is sometimes impossible. Identifying birds based on one characteristic alone is sometimes inaccurate. While well-known traits such as the larger head of the Cooper's Hawk or the square-cut tail of the Sharp-shinned Hawk frequently are reliable, these traits vary often enough to cause some confusion. Noting a bird's overall shape combining the head, tail, wing, and body together is the most reliable means of identification. Remember, pointed winged birds are not always falcons, long-tailed hawks are not always accipiters, and bulky-winged raptors are not always buteos. Take a minute to study the entire shape of a bird before naming it to a species.