(noun) The part of a bird's head immediately below the base of the bill and at the very top of the throat. On birds, the chin is a very small area and does not protrude, but it can be a good clue for the identification of certain birds. On some birds, such as comparing the ruby-throated hummingbird and the broad-tailed hummingbird, the chin color (black for ruby-throated and white for broad-tailed) can be one of the easiest and most substantive identification field marks.
To identify a bird using its chin, good light and a clear view of the underside of the bill is necessary. Note whether the chin color matches or is different from the throat, and note whether it is a plain color or if it has markings such as spots or streaks.
Photo – Ruby-Throated Hummingbird © thefixer