The rivers of the state include a number of small plateau streams flowing southward to the Sao Francisco River, and several large streams in the eastern part flowing eastward to the Atlantic. The former are the Moxoto, Ema, Pajehu, Terra Nova, Brigida, Boa Vista and Pontai, and are dry channels the greater part of the year.
The range in size is a wide one - from the tiny humming-bird to the ema, rhea, or American ostrich.
Among the wading and running birds, of which the ema is the largest representative, there are many species of both descriptions.
Brisson, the name has since passed into general use, especially among English authors, for what their predecessors had called the American ostrich; but on the European continent the bird is commonly called Nandu,2 a word corrupted from a name it is said to have borne among the aboriginal inhabitants of Brazil, where the Portuguese settlers called it ema (see Emeu).