 The remiges of ratites are soft and downy ; they lack the interlocking hooks and barbules that help to stiffen the flight feathers of other birds . In addition , the emu 's remiges are proportionately much reduced in size , while those of the cassowaries are reduced both in number and structure , consisting merely of 5 – 6 bare quills . Most ratites have completely lost their rectrices ; only the ostrich still has them . 
