Why do birds have wings?

Interesting theory......I would say that birds have wings mainly as an aid to almost evrything they do. Carnivorous birds need their wings to swoop down on smaller birds. All birds( that have wings and are capable of flying) use their wings to evade predators and humans. They use them to hunt, to migrate, to collect materials for their nests....many things would not be available to brids if they did not have wings, and most of those things neccesary, hence the answer. They just need them.