Why do vultures, eagles, kite,etc fly usually in a circular motion

i have often seen them fly like that. Why they do so? and which one according to u can fly to the most height?

They usually do it to gain altitude. It is called riding a thermal.

"Thermals are updrafts of warm air that rise from the ground into the sky. By flying a spiraling circular path within these columns of rising air, birds are able to 'ride' the air currents and climb to higher altitudes while expending very little energy in the process. Solitary birds like eagles and hawks often take advantage of thermals to extend their flight time as they search for food. Social birds that fly in large flocks also use thermals to gain altitude and extend their range during migration."

http://www.aerospaceweb.org/question/nat…

Of course, a large predatory bird can ride the thermal in relative safety, because only another bird of prey can attack it with sufficient force to cause danger. Smaller birds that try to do it alone will probably end up being a meal for a falcon or hawk. Since predators cannot predict when their next meal is likely to come, they try to conserve energy by riding a thermal to gain altitude before they start soaring. Many migrating birds also use the thermals to gain altitude before they cross a body of water.

They soar on uplifting air currents and the most efficient way of doing it is by moving in circles. In this way they can gain height using almost no energy. All these birds have superb eyesight and can spot possible food from a great altitude, but vultures soar the highest, having been observed at a height of seven miles above the African Rift Valley..

because there hovering over their prey, or it could be them soaring in a breeze which is circular, hpe it helped

kite because of the string birds because they want to