An Andean condor soars near a pinnacle high over a glacially formed valley between the Chilean and Argentinian regions of Patagonia. With wing spans that sometimes reach more than 10 feet, the condor of the Andes is the largest flying bird in the world. Because they are so large, they use thermals to keep them afloat as they search for carrion on the ground below. Roosting condors will pluck a feather and toss it into the air to check for the presence of active thermals. If the feather rises rather than falls, they will leap into the air and begin their graceful gliding motion, flapping their huge wings as little as possible.