Chim Ây is the male of the primordial pair of birds in the Mường creation epic Đẻ đất đẻ nước. After earth and water are born and the colossal si (banyan-fig) tree of the world has risen, Chim Ây and his mate Cái Ứa build their nest in its branches and produce a great clutch of eggs. From these eggs hatch the ancestors of the Mường, the Kinh (Việt) and the other peoples, so that the two birds stand at the head of the human genealogy. Sources vary in the number of eggs and in whether the birds are also called chim Tùng and chim Tót, but the mated pair Ây and Ứa is the constant figure of the hatching episode.