The common swift is a bird of extraordinary. Although we see many times and used to their presence, the Swift is probably better suited to the bird fly around the world.
First, the Swift is considered the fastest bird. Flies at a speed greater than any in its class. While it is true that the Peregrine Falcon can reach speeds higher (200 mph), these speeds are reached in fall, not horizontally.
A Swift may be flying at 150 mph and the alpine swift to 170 mph. A rate is not negligible.
Just see these wonderful birds shows that your body is adapted to speed on the fly. Its anatomy is the most aerodynamic of all birds (like the swallows). It has adapted wellto air your legs have become shorter and useless. Not being almost used weredownsizing and making them almost useless for travel by land. Eat, drink, mates and even sleeps in the air. To sleep in the air at dusk, rise and rise and rise as high as you lose sight, they begin to plan and sleep until dawn.
Another curiosity: When the Swift is subjected to inclement weather or a shortage of food, you can enter a state of near hibernation or "torpor." Thus, they consume less energy. Swifts adults can survive two days in this state and the chicks can survive and even five days.
Another more curious: How many years did not touch the ground only to nest and his paws are not developed, they need to make nests at some point. So drop and start flying as their feet are not allowed to walk, run or jump.