The family Balaenicipitidae also comprises only one species - the shoe-bill stork or whalehead stork, Balaeniceps rex. This bird stands 39-47 inches. high, on long legs, and has a fairly short neck, a large head and a broad ungainly bill, 8 inches long and shaped like a shoe. It is difficult to account for this shape, as the diet is similar to that of numerous other birds. Perhaps it is useful for probing in the mud for lung-fish, its favourite food. Besides fish it also feeds on frogs, turtles, young crocodiles and small mammals. This pale-grey bird inhabits the papyrus swamps of the upper White Nile and its tributaries on central East Africa.