Big Birds Can't Fly

It may seem strange that among the more than 10,000 bird species in the world today is a group that literally cannot fly or sing, and whose wings are more fluff than feather. These are the ratites: the ostrich, emu, rhea, kiwi and cassowary. How and why these birds abandoned flight has puzzled scientists since Darwin’s time, but DNA and dedicated research are helping to solve these mysteries.