Well, now it’s time to take a look at a few field marks. After observing the shape and size of the bird, its behavior and habitat and even its color pattern, you'll still probably come across two or three birds which are quite similar. This kind of situation calls for looking at field marks, to ensure you will identify the desired bird.
And now the obvious question arises. What exactly are field marks? The bright colored stripes, the various patterns and spots and distinctive highlights you see on a bird, are nothing but field marks. Although there are various reasons for the development of these patterns on birds, but birds, in fact, commonly use them to recognize their own species. And hence birdwatchers use it for the same function.
Before plunging into the massive array of field marks, we suggest you learn bird anatomy first. It makes it a lot easier to identify the color a malar stripe of a bird is, if you know that the line casting from the chin, dividing the throat and cheek. Within a blink of an eye you'll be able to see the contrast between an alula and a greater camouflaged bird.
In general, ornithologists convert birds into a globe and speak of its body parts like topographical zones. The primary divisions include the beak, back, breast, head, throat, legs, wings, and tail. These regions are even further divided
Field Marks on the Head
It’s only natural that you probably observed your enigmatic bird's head by this time. Make sure you start noting its field marks too (listed below in clockwise order, starting from the eyebrow stripe)
-Eye line (line inside the eye)
-Eyebrow stripe (or line over the eye, superciliary)
-Color of the lore (between Eye and base of the beak)
-Whisker mark (also called malar stripe or mustache)
-Color of lower and upper beak
-Eyering (ring of color around the eye)
-The eyecolor itself (iris) can also be very helpful
-Crown stripe (a stripe in the midline of the head)
-Presence or dearth of crest
-Field Marks on the Wings
The second best place to get clues after the head is the wings of the bird. Some groups like the vireos and warblers possess wing markings which can provide you an affirmation of the bird. In groups like flycatchers and sparrows, the nonappearance of wing markings is significant. Shorebirds, ducks, and raptors, among many others have a distinctive marking on their wings when the new feathers are exposed during flight. Make sure you look out for these field marks:
-Wing patches ( on the wing you can find blocks of color)
-Wing bars (stripes on the folded wing)
-Primaries (the long flight feathers on the external half of the wing)
-Secondaries (the flight feathers on the internal half of the wing)
-Wing lining (the feathers covers the underneath the wing)
-Primaries (the extended flight feathers on the external-half of the wing)
-Secondaries (the flight-feathers on the internal-half of the wing)
-Speculum (the patch of colored secondary that helps identify several ducks)
Once you observed the size, shape, behavior, color pattern, and territory than you can choose the common type of bird, you can choose few similar birds as well. The field marks are very helpful to identify certain types of birds.
The patterns on the birds are formed due to several reasons, but these stripes or patterns can help you identify their own bird species members. And bird watchers can also use them to identify.
Photo Credit: therealbrute