
I know that the answer to the question "For heavier feathered animals, how can traveling with friends be helpful?" is in "Many, if not most, birds migrate in flocks. For larger birds, flying in flocks reduces the energy cost. Geese in a V-formation may conserve 12–20% of the energy they would need to fly alone. Red knots Calidris canutus and dunlins Calidris alpina were found in radar studies to fly 5 km/h (3.1 mph) faster in flocks than when they were flying alone.". Can you tell me what it is? 


reduces the energy cost
