Researchers have finally found out just why many birds fly in a V-formation.
A team of scientists fitted tiny little computers to a flock of birds as they migrated south for the winter.
They found that flying near to each other helped the flock fly more easily through the air.
They time when they flap their wings to make the most of the upwards wash of air from the bird in front.
Flying this way means they save energy.
Lead researcher Dr Steven Portugal explained:
"They're seemingly very aware of where the other birds are in the flock and they put themselves in the best possible position."