The level of detail in your notes will vary, depending on your purposes. If you are merely recording a sighting of a familiar species for your own journal, you will not go into as much detail as you would if you were recording an unknown species or documenting a rarity. Listed below are several things to look for when making field notes. Start with your first impression of the bird. A bird's size can be a very important key to making an identification, but do not try to estimate a bird's length.
Most estimates are amazingly inaccurate and are therefore of little value.
Instead, compare the size of the bird to something nearby such as another bird or an object that can later be measured. Make note of the bird's proportions . Note any prominent feathers such as crests, tail streamers, or ornamental breeding plumage. After you have described the size and shape of a bird, you are ready to concentrate on colors and markings . Start with the head and move on to the back, wings, rump, and tail.