Why they fly the way they do, birds that is

Canada geese fly in a diamond formation
The U S Navy Blue Angles also use this formation
Photo: Jennifer Viegas

Shore birds fly at low level in a Hover formation
Photo: Jennifer Viegas

  Birds are just like a lot of us, do things the easy way, including flying.  Some birds fly alone, and some fly in neat formation and some in "swarms", I'll give you a link for more photos.
  Birds have flight feathers that can feel the air pressure, wind and direction of the wind, they use vision, and pick which ever "feels" the easiest.   They also make pretty pictures.
Visit this link:

http://news.discovery.com/animals/impressive-bird-flying-formations-photos-140116.htm