Silhouettes is an important part of size & shape identification.  Often you don’t need to see any color at all to know what kind of bird you’re looking at. Silhouettes quickly tell you a bird’s size, proportions, and posture, and quickly rule out many groups of birds – even ones of nearly identical overall size.  Silhouettes are so useful because they help with the first step in any identification: deciding what kind of bird you’ve got. Once that’s done, you’ve narrowed down your choices to one small section of your field guide.  Beginning bird watchers often get sidetracked by a bird’s bright colors, only to be frustrated when they search through their field guide. Finches, for example, can be red, yellow, blue, brown, or green – but they’re always shaped like finches. Learn silhouettes, and you’ll always be close to an ID.    Bird House on the Greenway  (source allaboutbirds.org)