That's why she keeps it long and thick, and it must be a wonderful place to warm up and rest. Still, I hope she washes it often if that's how she uses it.
The scene is awe inspiring. The little bit of lighting in that dark part of the forest (where those birds probably feel safest) gives her an angelic glow, and you gave her wonderful depth and shape. Everything, even the birds, trunk and leaves stand out three-dimensionally better than most 3D movies (and even my old View-Master). With Fluttershy looking so happy as she waits for them to eat, and the birds fluttering about, it's a lively scene even as she stays still. I can almost hear the chirping and the rustle of the leaves. I especially like that wide-eyed bird on the left who's staring at the pile of food in her hoof.