They say a bird is three things – feathers, flight and song. But what happens when you’re a bird who can’t fly, who can’t sing and whose feathers are closer to fluff? Is this an evolutionary joke? Flightless birds include ostriches, emus, rheas, cassowaries and kiwis; all have evolved independent of each other on different continents.
Nature: Big Birds Can't Fly, Wednesday at 8 p.m. on PBS 6.