 Species vary somewhat in the number of primaries they possess . The number in non @-@ passerines generally varies between 9 and 11 , but grebes , storks and flamingos have 12 , and ostriches have 16 . While most modern passerines have ten primaries , some have only nine . Those with nine are missing the most distal primary ( sometimes called the <unk> ) which is typically very small and sometimes rudimentary in passerines . 
