probably a Blue Jay juv on account of the blue

I don't think a Mockingbird would show the blue
2014-06-07 by David, hiking at Susquehanna - ID request
As to me thinking it might be a Mockingbird, it's possible, I guess, that the white mark on the wing is hidden by feathers from below. I couldn't get any speckling to show by manipulating photo either, so Blue Jay unless someone else knows better.