IT’S AN ASTOUNDING (surprised) FEAT (activity): Every summer, three billion birds of some 300 species—songbirds, waterbirds, and many others—migrate (migration, migratory, migrating)from northern Africa to Europe and Asia. In the winter, they return to Africa’s warmer shores. As they travel from one place to another, they navigate using the sun, the stars, smells, and land forms to help them find their way.Both large and small birds travel thousands of kilometers, often stopping at locations along the way to rest. (a topic sentence)In late fall in the northern hemisphere, for example, golden orioles fly from northern to southern Europe, and then cross the Mediterranean Sea into Africa. The birds often stop at different oases2 in northern Africa before flying almost 1,600 kilometers (over 1,000 miles) across the Sahara Desert and then on to central and southern Africa.(supporting sentences: details)