It's odd that although birds are todays version of dinosaurs, they are better evolved than us in some areas. Their eyes have the blood vessels on the outside unlike us (I don't think therefore they have a blindspot), they have more types of colour receptors, and their lungs are different - allowing them to happily fly at 30,000+ feet. They also appear to be able to fly in IFR - well, apart from the aspect of bumping into tall obstructions.