The bones of the modern birds have adapted well for their flight.

The entire skeleton weighs less than the weight of the bird’s feathers!

The bones are hollow and are braced by internal struts.

They are honeycombed and filled with air sacs.

The sacs are connected to the lungs so that

during the fight air flows through them.

This speeds up the supply of oxygen to the body tissues.

Even the beak is modified to reduce weight.

Unlike the human jaw which is made of thick heavy bone,

the bird’s beaks are made of light weight bones and do not have teeth.

The design is so light and strong that the golden eagle which can

have a wing span of 7.5 feet weighs less than four kilograms.