Link to video below.
We have a really, really picky 1-year-old male squirrel.
He runs laps around our house every morning for hours and then lately he's been doing this head rolling back thing a bit. We always follow it up with giving him yogurt, kitten milk, or a Tums piece (anything with calcium) and it seems to reside. He won't touch his squirrel blocks (we have Henry's picky swuirrel blocks ordered), loves all nuts, lettuce & apple, sometimes carrot. Besides that he's picky picky picky.
Does this look like calcium deficiency head nod to you?
http://photos.app.goo.gl/F6djB68xYevR8gVE6