Question: Can you name one adaptation that has made it easier for birds to fly?
Answer: Most, but not all, birds have hollow bones which make them weigh less and thus fly easier.
For instance the Brown Pelican, although the smallest of the pelicans, is a good sized bird with a length of four feet and a wing span of seven feet. But it only weighs 6 pounds. Ever wonder what it would weigh with solid bones?