What makes bird bones light?

Since most of the birds are flying, this has led to a significant reduction in their body. After all, the heavier the animal, the more energy it spends for movement. This is especially noticeable during the summer. For this reason, the birds have improved their aerodynamics and their skeletons have become lighter. This happened due to the fact that their bones do not consist of a solid mass, but have holes that are filled with air. But do not think that their bones have become weak because of this. The bones are even stronger than those of their reptile ancestors.