The Topography of Birds

Joe Meche is vice president of the North Cascades Audubon Society and is in his 10th year as editor of the chapter newsletter. Joe is also a member of the board of directors of the Washington Brant Foundation. He has been photographing birds and landscapes for more than 30 years and has been watching birds for more than 50 years.

While it might seem a bit hackneyed for the old hands and gonzo life listers to get into the how-to of identifying birds, keep in mind that we all began our respective bird watching odysseys as neophytes. Depending on the individual level of interest, we rapidly progressed through the common species and some of us eventually became rather adept at knowing the birds we were seeing.

But it wasn’t always so. The early stages of any pursuit always determine how long you stay with it. If you remember where you were when you started and even know a shortcut or two that you picked up along the way, be patient with beginners and lend a hand now and then. Add to the flock.

When we identify birds in the field using the Peterson System of Bird Identification, we segregate our targets into general categories, based on a short list of items such as shape and size, behavior and habitat. After we’ve decided on a category that fits a particular bird, we narrow our choices by utilizing primary clues that come from the basic topography of the bird we are trying to identify. The topography of a bird refers to its external anatomy and, while all birds are similar in many ways, there are subtle hints that tell us what we want to know; e.g., it’s a sparrow, not a duck!

The general topography of all living things is easy to perceive and to understand. We all have basic torsos with heads and species-specific appendages, as well as dorsal and ventral facets. Through the natural process, all animals have evolved to suit their respective environmental niches and needs. With the exception of slight variations in facial structure and coloration, humans look pretty much the same. Other animals vary according to species, but nowhere is the variation as unmistakable and even spectacular as in the great family of birds. While the basics are consistent throughout the avian world, every part of each bird is unique to the species.

When you look at birds across the broad range of species, you see classic examples of evolution at its finest. Through form and function, each species displays characteristics that evolved from the time birds left their reptilian ancestors some 150 to 200 million years ago. Even so, there are certain characteristics that birds still retain from their reptilian past, such as parts of their lower jaws and reproductive systems. Despite the similarities, birds have evolved their own unique body plan.

When we think of birds, we understandably think of wings. Birds are the only creatures that have wings and it stands to reason that they are the most conspicuous part of the topography of a bird. Wing shapes and sizes are as varied as the number of species and their needs, but all follow a general outline. When you look at a bird’s wings and learn the names of the parts that make up the wing, you’ll notice similarities between them and our own arms and hands.

From the point where it joins the body and beneath the covering of feathers, the extended wing shows a humerus and then a noticeable bend where the wing divides into a radius and an ulna. Sound familiar? These are the same bones that you have in your arm and the “noticeable bend” is your elbow. At the end of this bony structure are digits that compare with your thumb and fingers. In what can only be considered an evolutionary tradeoff, birds evolved with wings instead of arms and hands, and the result of this exchange is the unique avian bill.

Bills, also known as beaks, come in a multitude of shapes and sizes that vary by species and are generally specific to the birds’ methods of feeding. If you consider all the things that you do using your arms and hands, birds depend on their beaks and bills to accomplish similar tasks like feeding and defending themselves and their own from rivals and predators. In addition, birds also utilize this unique feature to build nests, preen their feathers and even to perform courtship rituals. From seed eaters to hummingbirds, and from woodpeckers and shorebirds to raptors, the beaks and bills of birds are masterpieces of design that follow form and function.

Sparrows’ bills are adapted to smaller seeds while the larger bills of grosbeaks give them the ability to crack open larger and heavier seeds. The hummingbird bill evolved from the need to probe into flowers to feed on the nectar that sustains their incredible metabolism, while woodpeckers’ sturdy bills enable them to build their homes as well as expose insects that form an important staple of their diets. Shorebird bills are designed for probing soft mud in search of invertebrates whereas the sharp and decurved bills of raptors enable them to tear their prey into manageable pieces.

The avian head is center of focus for the nervous system and the point where food enters the digestive system. As well as housing the eyes and the brain, birds’ heads also provide for communication within a species since many birds have adapted colorful plumages and crests, along with bill ornamentation to attract mates. The avian head is also species specific when it comes to flight and the increased demands of speed by birds such as falcons.

Feet are yet another fascinating component of the topography of birds. As important as their wings are, birds must eventually come down to rest, so their feet are equally important appendages. The feet of raptors are important in catching and killing prey animals. After the prey has been dispatched, raptors use their feet to hold the prize while they tear it apart with their bills. Even the most aerial of birds, the swifts and swallows, eventually need their feet to roost during their off-duty hours. The webs or lobes of the feet of diving birds make it possible to pursue prey underwater, and many birds that spend their lives in forested areas cling to tree trunks quite proficiently, thanks to the structure of the avian foot.

Bringing up the rear (bad pun) is the tail. The tails of birds provide that all important steering mechanism that is crucial to flight. Aircraft designers know the importance of the tail and utilize a series of vertical and horizontal stabilizers to simulate the efficiency of the avian tail. Again, following form and function, the hindmost part of a bird’s topography provides the precise amount of maneuverability required by the specific needs of the bird to which it’s attached.

While we often use color as a clue for identifying birds, consider a black and white world where you must draw on other facets to identify your quarry. Learn to recognize birds by their sizes and shapes along with the individual topography of individual species. It will add to your understanding of what makes birds work and it could even make you a better birder! Knowing the different parts of birds can be as useful as knowing the parts of your car when it breaks down in some out of the way bird-watching hotspot. It has happened before — and it will happen, again. §

A wonderful bird is the pelican
His bill can hold more than his belican
He can take in his beak
Food enough for a week
But I’m damned if I see how the helican.