I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "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."? 

While saving energy is a big benefit, which feathered animals experience another benefit of getting to their destination sooner?