Argh! Almost finished with my response then lost the page. Rather than repeat everything, I'll go right to what I noticed because this was a photo: The different shapes and textures of the feathers, and that one foot was not fully grasping the branch. Yes, this would be the questions I would be asking ... and perhaps with a bird in front of me, I'd get the answer through patient observation. And now that I found the edit button, I will add that I took your bird painting class a few months ago (waxwing) and learned about feather structures then!