Birds don't need maps!

Many birds make long journeys twice each year as they migrate between their winter and summer homes. Arctic terns fly more than 10,000 miles from the South Pole to northern Maine. Tiny little hummingbirds fly nonstop over the ocean for 500 miles. How do they know which way to fly? Why don't they get lost? Read and find out the many ideas scientists have come up with to explain this mystery.