On holiday watching hundreds of Swifts. Their flying makes Red Arrows seem like amateurs. Their aerial flying display is breath taking. How come they do not bump into each other? They were flying in groups a few days ago but now seem to be pairing up.
They seem to be catching flies. Do they fly with their beaks open hoping to catch something? Can they see the flies while flying at remarkable speeds, do they echo locate. How many flies do they need to eat to maintain enough energy to fly?