Yes, definitely an immature European Starling. Hirundo82 has it right; it is a young bird molting into adult plumage. The head still has the gray immature plumage, while the body plumage is of adult type.
Sorry for the delay in replying, but I am birding in Oaxaca at the moment and posting from an internet cafe in a small town near the mountains. Great looks at Red Warbler and other endemics yesterday!