Page 152 - Wonderful Creatures: Children! Have You Ever Thought ?

WONDERFUL CREATURES

BIRDS’ TECHNIQUES

FOR GLIDING

It requires a great deal of energy to fly. However, birds are small
creatures and the energy they can store in their bodies is limited.

Birds obtain most of the energy they need by means of applying
special flying techniques. Gliding in the air without flapping their

wings is one of the techniques that they use most. For example,
vultures employ a special method based on rising heat currents in

order to glide at a convenient altitude. Gliding from one current to
another, they can cover a vast area in a day.

Migratory birds, too, make use of gliding techniques to save energy.
Storks, for example, use heat currents to fly during migration.

White storks of central Europe migrate to spend winter in Africa
and cover a distance of about 7,000 kilometers (4,350 miles). If

they were to flap their wings all the way to their destination, they
would have to take four breaks during the journey. Yet white

storks complete their journey in three weeks by gliding between
the heat currents for 6-7 hours a day and thus saving most of their

energy.

Since the sea warms up more slowly than the land, there are no
heat currents over the sea. For this reason, migratory birds prefer

to migrate over land instead of making long sea journeys. You may
have seen flocks of storks that cover the sky at certain times of the

year. That is because storks, too, prefer to migrate over land. You

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