We have a lot of Canadian geese, many living year round in our area. There is a coal fired electric plant near where I live on the Lake Erie shoreline that has a warm water discharge that keeps open water for them during the winter. They utilize my pasture and I enjoy watching them. From what I have read, they can fly much farther as a group in V formation because the lead bird breaks the air resistance and the rest have easier flying in the slipstream created. The lead bird does tire more quickly and will drop back and another will take the lead. Some claim that dominate females usually are the leaders. They definitely make quite a racket calling back and forth while in flight. I don't know why one side of the V formation is longer than the other, it isn't like that all the time, but it does happen quite frequently. Big John's explanation sounds logical though.