Why do Geese Fly in a V

The fall migration of birds is well underway.  In the meadow outside my home in NH, there are flocks of white-throats sparrows and juncos feeding on seeds and insects.  Also there is the lovely sound of geese overhead flying in formation towards the beaver pond down the hill.  Have you ever wondered why geese fly in a V-formation?  Migration uses up lots of precise energy.  By flying in a V, the flock is conserving energy.  How?  Each goose flies slightly above the one in front of it.  This cuts down on wind resistance because the flapping of the bird in front creates an uplifting draft of air making it easier for the bird behind it to fly.  The energy saved in flight can be as much as 50%.  Therefore the lead bird is working the hardest while the rest of the birds can glide more and use less energy.  When the lead bird tires, it will fall back in the formation to an easier flying position and another bird will take over the lead.  This way the flock shares the hardest work.  Also, this type of formation allows for the birds to keep track of each other.  This assists in the communication within the flock and its coordination.  Who are in the flocks? Usually they are individual or multiple family groups.  Research shows that geese families will stay together during migration and in their winter feeding grounds.  It isn't until the springtime when they return to their breeding grounds, that the yearlings will venture off on their own. Fun Fact:  A group of geese on the ground is a gaggle, but a flock in  the air is a skein.  Photo:  About.com - San Francisco