ADDO, South Africa — Through the narrow slit of the underground hide in front of the water hole, an African morning revealed itself. The sun painted the earth orange. A lion stepped out of the bush and a small herd of perfectly camouflaged kudus, a large antelope-like animal, started and bolted away.

Soon a single bull elephant appeared where the lion had been, shaking his head as if scanning the bush. After a while, five female elephants descended the orange hillside to drink.

Even from a distance it was easy to tell they were females; in South Africa’s Addo Elephant National Park, they are almost always the ones without tusks.