Lake Natron is an alkaline lake from tectonic origin, adjacent to the Ol Doinyo Lengai, the only active volcano in Tanzania. Fed only by rainwater and a few small streams, Lake Natron is endorheic, meaning that the water is discharged through evaporation. This water is extremely loaded salts which give rise to micro-organisms. The lesser flamingo - Phoeniconaias minor - find in this water an ideal food and Lake Natron is therefore an ideal reproduction of this species. The largest gatherings of lesser flamingo can reach 2.5 million.