There are over 10,000 species of birds worldwide, and they come in many shapes and sizes. However, in this article, we're interested in the world's largest extant (still alive and not extinct) birds. This list is based and ordered on the mass of the bird.
The biggest bird by mass in the world is the Common Ostrich (Struthio camelus) which lives on the plains of Africa and Arabia. The males can reach heights of 2.8m (9.2 ft) and weigh over 156kg (344 lb). The bird with the largest wingspan is the Wandering Albatross (Diomedea exulans), found in the Sub-Antarctic oceans. The length of these birds, from head to tail, can go up to 1.44m (4.7 ft) with wingspans recorded at 3.65m (12 ft).
The largest bird in the world by mass, the Common Ostrich.
The largest bird in the world by wingspan, the Wandering Albatross
The largest flying bird in the world by wingspan is the Wandering Albatross, also known as the snowy albatross, white-winged albatross or goonie. As mentioned above, these birds can have wingspans of up to 3.65m (12 ft). They use these huge wings to cover thousands of miles in a single journey.
Wandering Albatrosses are known to sometimes go a year or more without setting foot on the ground. They will, however, touch down on the sea to feed on squid and fish.
By average body mass
The largest flying bird by body weight is the Great Kori Bustard (Ardeotis tardi). These birds can reach weights of up to 18kg. Because of their weight, it can be difficult for them to take off, and actually, they take off by running like a aircraft taxiing. They are found throughout Southern Africa and are especially common in Botswana and Namibia.
Like most bustards, the great kori bustard is a ground-dwelling bird and an opportunistic omnivore.
Wandering Albatross in flight
Great Kori Bustard
If you accept new world vultures into the bird of prey category - which most people do consider, then the largest bird of prey is the Andean Condor (Vultur gryphus) found in western parts of South America. These birds can have wingspans of up to 3.2 m (10 ft) and reach weights of 15 kg (33 lbs).
Excluding the above, the next largest bird of prey is the Cinereous Vulture (formerly known as the Black Vulture). These vultures can reach weights of up to 14 kg (31 lb), length of 1.2 m (3.9 ft) and have wingspans of over 3 m (10ft). These scavengers were renamed to avoid confusion with the much smaller and separate species known as the American Black Vulture.
Andean Condor in flight
Cinereous Vulture (formerly the Black Vulture) in flight
The largest bird in history was the Elephant Bird (Aepyornis) which lived in Madagascar and is believed to have become extinct around 1,000 years ago. These birds reached heights of over 3 m (9.8 ft) and weights of over 500 kg (1,100 lbs). The closest living relative to the elephant bird is the kiwi.
An illustration of the largest birds in history, the Elephant Bird
The largest falcon in the world is the Gyrfalcon (Falco rusticolus). Females are larger than males and can reach weights of 2.1 kg (4.6 lb), wingspans of 1.6 m (5.2 ft) and lengths of 0.66 m (2.2 ft). These falcons are similar in size to most buzzards but are generally heavier in the main.
Gyrfalcons breed on the islands of North America, Arctic coasts and tundra and in the Eurosiberian region - they are mainly resident birds.
Biggest falcon in the world, the Gyrfalcon (Falco rusticolus)
The largest owl in the world is between the Eurasian eagle-owl (Bubo bubo) and the endangered Blakiston's fish owl (Bubo blakistoni) which lives in Japan and coastal Russia. Both of these owls are similar in size and can reach weights of 4.5 kg (9.9 lb), wingspans of 2 m (6.6 ft) and lengths of 0.75 m (2.5 ft).
Not only is the Eurasian eagle-owl the largest owl in the world, but it is also one of the most widely distributed across the world. There is an estimated population of up to 2.5 million of these birds spread across a range of Europe and Asia covering around 32 million km2 (12 million sq mi).
Blakiston's Fish Owl
The largest flamingo in the world is the Greater Flamingo (Phoenicopterus roseus). These flamingos can be found across Eurasia and Asia and are also one of the world's tallest flying birds with a typical height of up to 1.53 m (5 ft) - only the tallest of cranes are taller. Males have been recorded at heights as high as 1.87 m (6.1 ft) and weights of over 4.5 kg (10 lb). As with other flamingos, the wingspans of these birds is relatively small, ranging up to 1.65 m (5.4 ft).
The biggest flamingo in the world, the Greater Flamingo
The largest penguin in the world is the Emperor Penguin (Aptenodytes forsteri) which is found across the Antarctic. These penguins can reach heights of 1.35 m (4.4 ft) and weights of 46 kg (101 lb). They are both the tallest and heaviest penguin globally, and like all other penguins, they are flightless birds.
The emperor penguin is the only penguin that breeds during the Antarctic winter and will trek distances of up to 120 km (75 miles) over the ice to reach breeding colonies containing several thousands birds.
The largest penguin in the world, the Emperor Penguin