Watch Attenborough's Big Birds (2015) Official Trailer

Meet the big birds, a feathered family who have never flown a day in their lives! From ostriches to kiwis, these bizarre birds appear to be nature's greatest novelty act. How they came to be and how they continue to survive is a fascinating tale that has long captivated Sir David Attenborough. It is a story of dedicated dads, enormous eggs and a serious need for speed. And far from being the court jesters of the animal world, these flightless curiosities once nearly ruled the land.