Swifts live in perpetual summer. They inhabit the air like nothing on the planet. They watched the continents shuffle to their present places and the mammals evolve. They are not ours, though we like to claim them. They defy all our categories, and present no passports as they surf the winds across the worlds. They sleep in the high thin air - their wings controlled by an alert half-brain. This is a radical new look at the common swift - a numerous but profoundly un-common bird. Foster follows the swifts throughout the world, manically, lyrically, yet scientifically. The poetry of swifts is in their facts, and this book draws deeply on the latest extraordinary discoveries.