Excerpt: The Young Birder's Guide to Birds of Eastern North America

June 16, 20084:35 PM ET

Identification Basics

Identifying birds is at the very heart of bird watching. Each bird encountered is like a little puzzle or mystery to solve, because, while birds of a single species all share a certain set of physical traits, no two individual birds, like no two individual humans, are exactly alike. You solve the mystery of a bird's identity by gathering clues, just like a detective. Most of the clues we birders use are called field marks. Field marks are most often physical things we can see — visual clues such as a head crest, white bars on the wing (called wing bars), a forked tail, patches of color, spots on a breast, rings around eyes (yes, called eye-rings), long legs, and a curved bill, for example.

But field marks also include behavior, such as hovering in flight, probing with a bill, pecking on a tree (woodpecker!), and flitting about actively. And field marks include sounds, too — songs, calls given in flight, chip notes, and even the whistle of wings. When added up, these clues should lead you to a correct answer: the bird's identity.

New birders are wise to start with the obvious visual field marks of a bird. You'll want to collect these field-mark clues in a logical way: start at the top of the bird (by the head and bill) and work your way down and back. Most North American birds can be identified by field marks above the bird's shoulders: on the bill, head, and neck, and near the bend of the wing.

Tip: Resist the urge to take a quick glance at a strange bird, note one field mark, then drop your binocs and grab the field guide. Birds can fly and are prone to sudden decisions. Field guides are books and cannot fly. Watch the bird as long as it lets you, and then reach for the field guide. Some birds may appear to be completely plain and will require a longer look. But plainness itself can be a field mark! Don't give up. The clues are there, waiting for you to notice them.

Remember: Look carefully at your mystery bird, gather the clues, and then refer to your guide to solve the mystery. The challenge of identifying birds is one of the best parts of bird watching. It can seem difficult and frustrating, but there are a few hints that will make it easier and more enjoyable.

The steps for identifying a bird are the same no matter where you are, no matter what bird you are watching.

Here are some basic steps to follow.

Size: The first thing to notice is the size of the bird. Size will narrow down your choices a lot. To start with, think of birds as falling into the categories of small, medium, and large. Try associating those categories with objects you are familiar with: a cell phone, a soda can, a loaf of bread. It won't be long before your judgment of a bird's size is automatic.

In most field guides, the size given is for the bird's length, measured from the tip of its bill to the end of its tail.

Here is an important point about judging size: A bird hunched over on the ground picking up seeds appears shorter and fatter than the same bird perched on a tree limb. Birds startled by a sudden noise or the appearance of a predator will stretch their necks, making them look considerably longer than when they are relaxed. Also, birds look thin when they are holding their feathers close to their bodies, and fat and round when they have fluffed them out, as they do in very cold weather. The key to judging size is to watch the bird for several minutes and to look at both its length and its bulk.

Look at the Bird: Start with a general impression: What is the most noticeable thing about this bird? The answer to this question is a basic description of the bird's shape, size, and appearance. For example: This is a big, tall, thin bird with long legs. Sometimes the general impression is enough; it is certainly a good starting point.

Begin at the front (the head or bill) of the bird and work backward. The key to identification is often in the pattern of the head. Does the bird have stripes on the head? A line over the eye? Is there a noticeable color on the face or head? Pay particular attention to the bill. Bill shape and size often indicate the family to which a bird belongs. A family is made up of bird species that are closely related and that share many characteristics.

For example: All sparrows have short, thick bills. Warblers have short, thin bills. Thrashers and mockingbirds have long, thin bills, usually down-curved.

After you have looked at the head, check the back, wings, and underparts, ask yourself: Is the back darker or lighter than the head or the belly? Does it have streaks? Are the underparts plain, or are there streaks or spots? Wings often provide a key identification feature: the presence or absence of wing bars. Wing bars are contrasting, usually pale, lines across the wings. Many groups of birds — warblers and sparrows, for example — are divided, for ID (identification) purposes, into those that have wing bars and those that do not. Last, look at the tail. Is it long or short, rounded or forked, darker or lighter than the back? Are there white panels or spots? Is it all one color? Does the bird bob or wag its tail persistently? Is the tail held cocked up or angled down?

All this sounds like a lot to remember, but after a few tries these questions will become automatic.

As in most things, there is no substitute for practice. Try these steps several times on familiar birds. Remember, the key is to look for the most obvious clues to a bird's identification.

Range: Expect the expected. A bird's range (where it is regularly found) can be a valuable clue to its identity. If you live in Florida and identify a bird at your feeder that, according to the field guide map, occurs only in Oregon, your identification may be incorrect. Reconsider the other clues you have and try again. Birds occasionally show up a long way from where they are supposed to be, but it isn't common.

Look at the Book: Now it is time to use your field guide to identify the bird you have been watching. At first, the number of choices can be confusing. For new bird watchers, one of the best ways to find a species in a field guide is simply to start at the beginning and work through to the end. Don't worry, it won't be long before you are instinctively turning to certain sections. Small brown birds with thick bills will have you checking the sparrows, and chunky gray-on-brown birds with long tails and bobbing heads will have you checking the pigeons and doves.