The largest bird that ever lived is the elephant bird or vouron patra (Aepyornis maximus) which became extinct about 1,000 years ago (although sightings were reported as late as 1658). This flightless bird from the island of Madagascar grew to around 3-3.3 m (10-11 ft) tall and weighed about 1,100 pounds. 

Only the Moas from New Zealand were taller than the Elephant bird (some reached thirteen feet) but they were not so massively built. The Elephant bird’s eggs were larger than those of any dinosaur, and are the largest single cell ever to exist on Earth. They had a liquid capacity of 2.25 gallons, the equivalent of 7 ostrich and 12,000 hummingbird eggs.