The ostrich, running in herds in southern Africa, is the largest bird in the world. As well as being able to run at enormous speed from danger, the ostrich has powerful legs and sharp claws, which can deliver a kick hard enough to kill many predators.
The largest extant bird species, a member of the struthioniformes, is the ostrich (Struthio camelus), from the plains of Africa and Arabia. A large male ostrich can reach a height of 2.8 metres (9.2 feet) and weigh over 156 kilograms (344 pounds). A mass of 200 kg (440 lb.) has been cited for the ostrich but no wild ostriches of this massive weight have been verified. Eggs laid by the ostrich can weigh 1.4 kg (3.1 lb.) and are the largest eggs in the world today.
The largest extant bird by wingspan is the Wandering Albatross of the sub-Antarctic oceans. The maximum dimensions in this species are a length of 1.44 m (4.7 ft.) and a wingspan of 3.65 m (12.0 ft.).
The largest bird in the fossil record may be the extinct elephant birds of Madagascar, whose closest living relative is the kiwi. They exceeded 3 m (9.8 ft.) in height and 500 kg (1,100 lb.). The last of the elephant birds became extinct about 300 years ago. Of almost exactly the same upper proportions as the largest elephant birds was Dromornis stirtoni of Australia, part of a 26,000-year-old group called mihirungs of the family Dromornithidae. The largest carnivorous bird was Brontornis, an extinct flightless bird from South America which reached a weight of 350 to 400 kg (770 to 880 lb.) and a height of about 2.8 m (9 ft 2 in). The tallest bird ever however was the giant moa (Dinornis maximus), part of the moa family of New Zealand that went extinct around 1500 CE. This particular species of moa stood up to 3.7 m (12 ft) tall, but weighed about half as much as a large elephant bird or mihirung due to its comparatively slender frame.
The heaviest bird ever capable of flight was Argentavis magnificens, the largest member of the now extinct family teratornithidae, found in Miocene-aged fossil beds of Argentina, with a wingspan up to 5–6 m (16–20 ft.), a length of up to 1.26 m (4.1 ft), a height on the ground of up to 1.5–2 m (4.9–6.6 ft.) and a body weight of at least 71 kg (157 lb.). Rivaling Argentavis in wingspan if not in bulk and mass, another contender for the largest known flying bird ever is Harpagornis moorei, which had a wingspan of up to 7.3 m (24 ft.).
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