WHAT HAS WING SHAPE TO DO WITH FLIGHT?
Birds wings are shaped differently depending on how they need to fly. Fast flight demands narrow wings, like those of swallows. While quick flight in woodland needs short rounded wings like those of bluetit falcons change the shape of their wings, from long and narrow for fast flight to swept back for diving at top speed gannets have long wings for long distance flight and gliding when they dive to catch fish they fold their stretched wings backwards like the flight of a dart.
imgsource: https://speakzeasy.wordpress.com/2013/06/29/of-birds-wings-and-burdens/
There is a right and a wrong in the universe, and the distinction is not hard to make
lift ,gravity,drag and pressure are the forces necessary for an object to leave the earth`s surface for birds we talk about wing span or length as it affects all the above forces hence its eventual flight capabilities