The mud flats surrounding Delta, B.C., are a magnet to the giant flocks of Western Sandpiper that feed along the water line, and to bird watchers who try to catch a glimpse of the tiny timid bird during the yearly migration from South America to Alaska every spring. The flight of the birds, which individually weigh less than an iPhone, create giant waves in the sky. Between now and the first week of May, hundreds of thousands of the birds will make their way through the flats.