Niokolo-Koba National Park is nine thousand square kilometres of Sudano-Guinean savanna along the upper Gambia river in the Tambacounda region of southeastern Senegal, the last wild home of the western giant eland, the largest antelope on Earth, and a refuge for the lions of West Africa, and it is driven on laterite tracks from the lodge at Simenti, boated on the river and walked with a ranger. The park is the biggest in the country and one of the oldest in West Africa, and its animals have thinned, so that its elephants have all but vanished and a single old bull known to the rangers as Ousmane may be the last; the river circuits out of Simenti follow the Gambia at first light through gallery forest and out onto the floodplain, where roan, kob, waterbuck and buffalo graze and the giant eland is seen with luck, and the boats go out onto a river lined with borassus fan palms, hippos surfacing midstream and crocodiles sliding off the sandbars. On the sandbars patrol the Egyptian plovers, the bird Herodotus claimed walks into a basking crocodile's mouth to pick its teeth.
The pond below the hotel at Simenti draws a steady procession through the dry months, kob and warthog first, then the bigger antelope, all edgy and quick at the water, and by February the seasonal pools have dried and the game is bound to the river, the densest viewing of the year and the hottest. On foot the visitor goes only in a ranger's company, which turns out to be the point, since they read the tracks, the dung and the alarm calls the vehicle drowns out. Around Mont Assirik in the park's heart live chimpanzees in the hottest, driest and most open country any chimpanzee occupies, the northwestern edge of the whole species, studied for decades. Through the northern winter migrants from Europe swell the park's 330 species of bird. Niokolo-Koba is the savanna Senegal kept, and the giant eland has nowhere else.