Why swiftlets flying high in the sky?

It is a common scene that swiftlets flying round and round above the canopy of the trees. Do they flying for fun?

Study showed that swiftlets are foraging for food during flying high in the sky. One would wonder if there is anything high up in the sky.

Actually, small insects are floated up by hot air in the bushes or jungle during day time. They are plenty in the sky. Unfortunately, we cannot see them by our naked eyes.

Swiftlets pick up these insects while flying. Some make the insects into a small ball to feed the infants. See how wonderful the nature is!

Posted by Chai Yong of http://www.banyan-bird-nest.com