Most bird bones are so hollow and light, their feathers weigh more than their skeleton!

Birds like flying, you could even say that most of them need to fly. As a result of their winged capabilities, the rest of their body has adapted to making themselves as light as possible.

Some of these minor changes in the birds genetic make up is that most birds, have hollow bones!

Skeletal adaptations are crucial to birds, because they lend strength to to the skeleton so that the thrust generated by the birds wings can result in a perfect lift.

This optimal lift makes it so much easier for birds to move through the air!

Sometimes, the birds feathers are heavier than the bones inside of the bird! Another quick little fact for you to think about is that pigeon feathers make noise if you swing them through the air, while if you swing a hawk's feather through the air - it isn't almost silent!

This is because pigeons don't hunt, so they don't need to be quiet whereas hawks do!

(Source)