Question

The first person to anwcer the question i will put you as brain list

Answer 1

Answer:

So they are lighter and move quicker.

Explanation:

With the small wings and bodies birds have it would be hard for them to escape predators and lift their own weights if their bones were dense like humans' bones. The hollow part of the birds' bone is connected to their lungs so they have enough oxygen to fly easily. Hope this can help you! :)