“We discovered this tiny sandy island in the Okavango,” says Dereck. “It is extraordinary because it became totally isolated from the mainland 15 years ago when the course of the river changed, and a huge herd of buffalo and lions were trapped on a piece of land measuring 200 square kilometres.”

Through this twist of geographical fate, these two ancient species are now engaged in a desperate battle of survival — watched by six bemused refugee wildebeest and a handful of similarly outnumbered warthogs.

Thus, the island has become a unique, ecological experiment. In order to exist without the customary spectrum of weaker African prey like zebra, giraffe and impala, the Duba lions have had to develop distinct strategies in order to trap the single available food source.