Laguna Colorada is the colour of dried blood, and you could wade across it. The lake covers sixty square kilometres of the Bolivian altiplano at 4,278 metres and is nowhere more than thirty-five centimetres deep. That shallowness is the whole story. Rust-red sediment hangs stirred through water too thin to settle it, and algae flood the same water with pigment to screen themselves from the ultraviolet light up here. The colour shifts through the day, brick in the morning and deep crimson in the late afternoon, when the low sun rakes across the shallows. The white patches drifting on the red are not ice but borax, a mineral salt that crusts into pale islands and ridges. The shore is stiff with salt under your boots and edged with low golden reeds, and a rise of bare altiplano behind it takes in the whole basin: red sheet, white lacing, a far wall of volcanoes.
The birds are why the reserve exists. Three flamingo species feed in these shallows at the same time — James's, Andean and Chilean — sweeping their bent bills side to side and stepping slowly over the mineral flats. They do not compete for it: each bill strains a different size of food out of the same water, so thousands feed side by side. From the shore they read as one pink line until you are close enough to separate them. They breed in the southern summer, from November to April, when rain lifts the water and chicks appear on cone-shaped mud nests. Nights at this height drop below freezing in every month of the year. The James's is the one to pick out, paler in the body, with brick-red legs and yellow at the base of the bill, and it was written off as extinct for decades. Then an expedition found it in 1957, nesting out on the borax islands where nothing walking the shore can reach, and that is still where its chicks hatch: on a lake you could cross on foot.