Bird life on the lakes also varies enormously according to the time of year. From October to April the lakes are alive with waterfowl which have migrated down from the northern hemisphere. For the remainder of the year the resident birds have the lakes to themselves. The commonest water bird on the lakes is the little grebe, a small greyish brown bird with a chestnut-red face and throat, with a high pitched trilling call. Easily distinguished birds are the flamingos.
Lesser flamingos are smaller than the greater flamingo, and their plumage is much pinker.
The bill is dark red in the lesser and pink with a black tip in the greater flamingo. Lesser flamingos feed on algae whilst the greater flamingos eat tiny crustaceans which they filter through their bills. These different diets enable the two species to coexist in the same habitat. In agricultural settlements around Arusha National Park, Egyptian geese often cause damage to newly planted crops like maize. The routes around the lakes have several observation points and hides and they should be taken in an anticlockwise direction.