Flight: They move about by flying and prefer the higher altitude pressures. They are able to remain in flight for months until their seasonal migration to warm climates. But they don't rely on their fins to keep them aloft, rather, they use giant balloon like organs inside their bodies to stay afloat.
They fill these organs with gasses obtained by eating large amounts of earth and plant life from the ground.

Echolocation: By making long mournful sounds they are able to detect anything around them in a three mile radius.

The Sky Whales are normally docile creatures that float high in the atmosphere eating bugs and other tiny creatures as their mainstay.

However, whenever they "beach" themselves in order to restore their gasses they become very aggressive and will attack any sort of threat that comes near them.

During their seasonal migration these sky whales are known to sometimes beach themselves right on top of small villages, eating anything nearby to restore their gasses.