Why don't birds flap their wings sometimes?

Answer 1

Birds ride thermals, as you would if you took a balloon ride. This saves energy. Imagine the hummingbird, who flies 3000 miles one way during migration. It takes too long to stop and eat all the time, so they ride the thermals. Different sizes and shapes of birds allow for differences in the way they fly. These differences are also helpful in identifying birds in the field. For example, ducks flap their wings very quickly, geese at a steady pace, and pelicans flap a few times and then glide for a few seconds. Generally, birds with larger wings do not have to flap as often but do not fly as quickly as birds with smaller wings.