If you’ve ever wondered which is the biggest bird in the world you’ve found your answer. The largest and heaviest living bird, the Common Ostrich can be up to 2.7 m (9 ft) high and weigh in up to 160 kg (350 lb). It is a flightless bird but it has unusually massive and powerful legs that allow it to run as fast as 65 km/h (40 mph). Ostriches are primarily herbivores but can on occasion eat insects.