Birds have adapted to flight through various anatomical features, and one of the key adaptations is their possession of lightweight bones.

Birds' bones are hollow and have a unique structure filled with air sacs, making them significantly lighter than the bones of most other vertebrates.

This reduction in bone mass allows birds to achieve the necessary strength and structural integrity for flight while minimizing their overall weight, which is crucial for powered flight.

Therefore, the possession of light bones is a critical feature that enables birds to fly efficiently.