Regardless of what you call them – submoustachial, malar, jaw stripe, mandibular stripe – the feathers along the side of the lower jaw are important for identification. Being able to distinguish this group of feathers, and confidently describe their color, is one of the trickiest and most useful skills in understanding head feathers.
Hopefully this short quiz will help.
With thanks, again, to Brian E. Small for providing the beautiful photos. You can see lots more at his website, and clicking any photo links there as well.
The color of the submoustachial