Dzanga Bai is a clearing of sand and mineral pools in the rainforest of the Dzanga-Ndoki national park, in the far southwest of the Central African Republic, where more than two hundred forest elephants gather at once to dig for salt, the largest gathering of the species known anywhere, watched from a platform at the edge of the forest through the afternoon. The bai is a natural opening in the forest where mineral-rich water seeps up through the sand, and the elephants come out of the tree wall at their own pace, a calf glued to its mother's flank, cross the open ground to the pits and dig with their trunks and tusks for the salts they cannot get from leaves; the count fills and empties over hours and peaks in the middle of the afternoon, with bongo and forest buffalo among them. Researchers have picked out more than 4,000 individual elephants here since 1990, about 85 per cent of them returning, and much of what the animals say to each other in the clearing is pitched too low for human ears, infrasonic rumbles that carry through the forest far beyond the bai.
The forest elephant is a separate species from the savanna elephant, smaller and straighter-tusked, and among the slowest breeders in the forest, a female having her first calf at around 23 and then one every five or six years. The park is reached from the village of Bayanga, and the Ba'Aka, the forest people of the Sangha, are its trackers: they lead groups of no more than three off the trail to a habituated family of western lowland gorillas, reading broken stems and the previous night's nests, and take visitors on a morning's net hunt, stringing long nets between the trees and driving the undergrowth toward them with shouts and song. From December to March the pan dries and the roads stay passable. Dzanga Bai is a salt lick that the forest elephants have made a meeting place, and the platform is the seat.