I like the alert pose, eye contact and setting. Could you have moved a bit to your left for a better angle? I might sharpen the bird a bit more and it could go a bit brighter for my taste. There are some dust spots in the BG.
The detail in the snow is excellent. Good shooting angle, and I like the hillside effect. Do agree with Axel about the head angle, but its close.
You could push the image a bit brighter if desired, as Axel mentioned. The highlight slider can come in about 8 points before any clipping shows up, gives a bit more snap to the whites, but its your call of course.
I like the fresh snow, and the pale blue hue of the sky with a small hint of cloud. Ptarmigan looks good, only the HA would have needed to be better. Personally I would have preferred half the empty space at bottom, and then some more above (pointing your camera up by a bit).
The technical aspects of the photo are good overall, IMO, Joel. You might try some tweaks as suggested above. Personally, I would have preferred a more relaxed looking pose. From a behavioral aspect, with its head stretched up as far as possible, the bird looks alert - to the point of being alarmed and ready to fly away. :)