The secretarybird (Sagittarius serpentarius) is an endangered species, but you do come across them in the Kalahari Desert. In Botswana's Kgalagadi Transfrontier Park, I followed two of them hunting on the ground in a dune valley for a mile or so with my vehicle on a gravel road. They caught the occasional small insect, a small snake, and then all of a sudden one chased this ground agama. It caught and killed the agama with its feet by trampling on and smashing the reptile’s head—the secretarybird is the only bird of prey that kills its prey with its feet. It then took it with its beak and threw it into the air to catch it again and swallow it head first, while closing the nictitating membrane over its eye for protection. It all happened in less than a minute.