Migrating birds fly in a V formation because it gives them the best of both worlds, reducing air resistance while allowing the geese or ducks in the back to see where they’re going.
Think of the V formation as the front of a boat cutting a path through water.
The first fowl in the V formation cuts through the air and blocks some of the air and wind resistance for the two birds behind it, allowing them to glide through the air using less energy.
Those birds do the same for the ones behind them, and so on all the way through the V. In this way, the birds can travel long distances with fewer rest stops during migration.
When the front bird gets tired, it drops back, and another takes its place at the front.