The information scientists have about how many miles a bird flies in a day comes from birds that have been banded or tagged.
This banding usually takes place when birds are migrating from one place to another. A bird is caught at some point on its journey, and a metal band is fitted around its leg.
The scientists then try to find the bird in the area they know will be its future home. According to the records, most birds are in no hurry when they make their long flight. Few travel every day. They may even make a stop for a week or so if food is plentiful.
Birds whose average speeds are 20 or 30 miles an hour usually travel about 160 miles a day.
Strong fliers, such as ducks and geese, cover as much as 332 miles a day. If birds start their travels late in the year, they fly more hours each day and take little time off to eat and rest.
Few birds fly more than eight to ten hours a day.
