There are 400 billion birds in the world, 250,000 planes, and one Superman. So, in answer to your question - probably a bird.

To the first two people who thought Superman was a bird or plane... why the hell were you so excited?

"It's a bird!" [Superman zooms down to inches away from the screaming guy's face] S: Birds can't go that fast Sean. What are you an idiot

I wonder if Superman ever put glasses on Lois Lane's dog & she was like, "I've never seen this dog before. Is this a new dog?"