Fastest flightless bird on land

The world's fastest bird on land is the ostrich (Struthio camelus) which, can reach speeds of up to 72 km/h (45 mph) when running.  Unlike most birds, the ostrich cannot fly, and therefore uses its powerful legs to sprint at such speeds. 

Interestingly, the ostrich has one of the largest strides of any animal, which can exceed 7m (23 ft) at full pace.

Cheetahs also have a long stride, covering 7-8 m (23-26 ft) in one stride.