Lapped-faced vulture (korvakorppikotka, Torgos tracheliotus) and three white-backed vultures (savannikorppikotka, Gyps africanus, also sitting in the top of the dead tree) stopping at a waterhole in Kgalagadi Transfrontier Park in South Africa.
Vultures have keen eyesight. It is believed they are able to spot a three-foot carcass from four miles away on the open plains. In some species, when an individual sees a carcass it begins to circle above it. This draws the attention of other vultures that then join in. (Source)