The main way we identify birds is by noticing how they differ from one another.  These differences are also at the heart of what makes us appreciate the incredible ways that birds are adapted to their precise ecological niches.

One way to get a handle on "bird diversity" is to keep in your mind's eye the image of a "Standard Bird." The Pigeon at the right makes a good Standard Bird, because there's nothing particularly mind boggling about it (though he is a bit pigeon-toed) so let's let him be our bird against which we compare all other birds.

Now let's look at how this "Standard Bird" idea works. How does the Williamson's Sapsucker, a woodpecker of high-elevation pine forests in western North America, at the left, compare with our standard-bird pigeon? The most conspicous differences are:

• The sapsucker's beak is long and chisel-like, very unlike the pigeon's

• Its feet have two toes pointed forward and two pointing backwards (our pigeon has three up front and one behind)

• The sapsucker's tail is so stiff that's its being used as a kind of "fifth leg" steadying the bird as it pecks and drills with its peak into the wood

Therefore, these three things, the sapsucker's beak, its feet and its tail, because they are so different from what we see on our standard-bird pigeon, are the basic special features of the Williamson's Sapsucker. Later if we want to distinguish the Williamson's Sapsucker from other woodpeckers, by then we'll already have a concept of "woodpecker" firmly established in our heads, so we won't need our Standard-Bird concept. Our Standard Bird is for bigginers...

Let's fine-tune our ideas about our Standard Bird concept:

Every bird has special markings or other features, or field marks, that cause that species to be unique. When you spot an unidentified bird, the first thing you need to do is to begin checking for field marks -- characteristics to help you name the bird when you go to your field guide. For example, if I were to spot the Golden-winged Warbler at the right, I'd immediately begin mentally cataloging the field marks. The little voice in my head would be saying "...yellow crown, yellow wing patch, black throat patch but gray chest, unstriped gray back, no white outer tail feathers... " By the time you notice so many field marks, usually the bird will have flitted away. However if you remember the field marks, you have him!. No other warbler than the Golden-winged has the combination of a black through and yellow wingbars, so just with those two features -- if you remember them -- once you look into your field guide, you'll be able to make a certain identification.

Differences in beak

This is such an important topic that we have a special page for bird beaks.

Same here. See our special page for bird feet.

Not many birds have the needle-tipped tail feathers like the Sage Grouse pictured at the left. The same can be said for Scissor-tailed Flycatchers in Texas and surrounding states which possess long, streaming tails accounting for about two-thirds of the bird's entire body length. Tail differences are usually rather subtle.

For instance, among the many sparrows, it's important to notice whether the tail's tip is rounded, squared, or notched. With look-alike species of migrating fall warblers, see whether or not two large, white spots occur on the tail's underside. To distinguish the various species of Myiarchus flycatchers, determine if the tail feathers are tinted with a lot, or a little, reddish color.

Extreme differences in odd places

Some birds are so uniquely colored, patterned, or structured that only one or two striking peculiarities set them apart from all other birds. Along North America's southern coasts, for instance, any black bird with a seven-foot wingspread and a bright red, balloon-like throat pouch is a Magnificent Frigatebird, and nothing else. Any tiny, beelike bird zipping from flower to flower in eastern North America north of Florida is a Ruby-throated Hummingbird. Any bird with crossed mandibles is one of the two species of North American crossbills.