Turkey Vultures is search of an updraft.

Ever wonder why vultures circle like this? It's not always what you think. They are circling and not flapping their wings but getting higher. This is because they are saving energy by utilizing the thermals or updrafts created by rising air on a sunny dry day. If you watch them circling notice they don't flap their wings but get higher and higher as the updraft takes them higher. They then can search for their next meal without working too hard.