Why do ducks geese etc fly in uneven v formation?

Birds flying in V-shaped formations save energy by utilizing the updraft created by the bird in front of them, allowing them to fly far with minimal effort. This updraft is created as the bird's wings push air downwards and backwards. The bird behind can then use this rising column of air to gain lift, reducing the amount of energy they need to expend in order to fly. By flying in this V formation, the entire flock benefits from the energy savings as they can cover longer distances without needing to rest. This adaptation is particularly important during long migrations or when carrying heavy loads.