Many birds migrate to where they can find food for the winter months.

Birds have to eat a lot of food to store fat for their journey.

Birds fly at different times of the year. This depends on how far north they live, and when their food supply is disappearing.

It requires a lot of energy to make the trips, so birds must find places to get food during their flights. If they can't find food, they weaken and are caught by predators (enemies).

Farmers do not want ducks and geese to settle on their fields and eat the grain. Hunters kill ducks and geese.

Strong winds can blow birds off their course.

Birds can get caught in storms and other bad weather.

Sometimes birds fly into tall buildings or towers.

Safe places for birds to stop, rest , and eat are disappearing.

Some birds fly at night and use the stars to help them.

Birds that fly during the day use the position of the sun as a guide.

Waterfowl follow rivers.

Hawks and eagles follow mountain ranges.

Scientists cannot fully explain how birds find their way.