The bird body structure is what kind of ？

　　Once you’ve looked at Size & Shape, Color Pattern, Behavior, and Habitat to decide what general type of bird you’re looking at, you may still have a few similar birds to choose between. To be certain of your identification, you'll need to look at field marks.
Field marks are the distinctive stripes, spots, patterns, colors, and highlights that birds have in such abundance and variety. Birds developed these patterns for many reasons, but one way they use some of these markings is to recognize members of their own species. And bird watchers can use them for the same purpose.

　　When you dive into the world of field marks, it helps if you learn a little bird anatomy. Trust us, it’s a lot easier to notice what color a bird’s malar stripe is if you know it's that line angling back from the bird’s chin, separating the cheek from the throat. You'll know the difference between an alula and a greater secondary covert in no time.
Ornithologists talk about parts of a bird by dividing its body into topographical regions. The main divisions are beak (or bill), head, back, throat, breast, wings, tail, and legs. Many of these regions are divided still further.