Many of the birds we encounter in our daily lives are small, often weighing just a few grams. However, some bird species are surprisingly large, towering over even the tallest humans.
The biggest birds in the world are typically flightless. Their inability to fly allows them to develop denser bones and heavier bodies. Instead of flight, they have evolved other adaptations for survival, such as powerful leg muscles that enable them to run at remarkable speeds to escape predators.
Despite their impressive size, none of today’s big birds come close to the elephant birds, members of an extinct family of ratites. The largest of these, Vorombe titan, was a true giant, weighing over 700 kg and standing approximately 3 metres tall, making it the biggest bird to have ever lived.
The common ostrich (Struthio camelus) is the largest living bird in the world, with an average weight of 104 kg and a length of 210 cm. It lays the largest eggs of any bird and holds the record for the fastest land speed, reaching up to 70 km/h. Ostriches are also believed to have the largest eyes of any land vertebrate, measuring an impressive 50 mm in diameter. Native to Africa, ostriches are now farmed worldwide, primarily for their feathers, leather, and meat.
In 2014, the Somali ostrich (Struthio molybdophanes), also known as the blue-necked ostrich, was officially recognised as a distinct species from the common ostrich. Slightly smaller than its relative, the Somali ostrich is distinguished by its blue skin on the neck and thighs, compared to the pink skin of the common ostrich.
The southern cassowary (Casuarius casuarius), also known as the double-wattled cassowary, Australian cassowary, or two-wattled cassowary, is the largest of the three cassowary species. It typically weighs around 45 kg and reaches an average length of 155 cm. It is found in north-eastern Australia, Indonesia, and New Guinea.
Slightly smaller, the northern cassowary (Casuarius unappendiculatus), also called the single-wattled cassowary, one-wattled cassowary, or golden-necked cassowary, has an average weight of 44 kg and a length of about 149 cm. It has a slightly smaller bill than the southern cassowary but longer toes. The species is endemic to the coastal swamps and lowland rainforests of northern New Guinea.
The dwarf cassowary (Casuarius bennetti), also known as Bennett’s cassowary, little cassowary, mountain cassowary, or muruk, is the smallest of the three species. Weighing around 20 kg and measuring approximately 125 cm in length, it inhabits the montane cloud forests and tropical rainforests of New Guinea.
Endemic to Australia, the emu (Dromaius novaehollandiae) is the second-tallest living bird in the world, reaching heights of up to 190 cm. It weighs up to 60 kg and measures between 140 cm and 165 cm in length. Female emus are generally larger than males, with noticeably wider rumps.
Emus have evolved for speed, and despite being flightless, they have vestigial wings, which they flap while running to help with stability. They have only three toes and a reduced number of bones and foot muscles, adaptations that enhance their running efficiency.
Uniquely among birds, emus have an unusual gastrocnemius muscle, a large, two-headed muscle in the calf responsible for ankle and foot movement. Unlike other birds, which typically have three muscle bellies – the thicker, central parts where the muscle fibres are most concentrated – emus have four, allowing for greater strength and endurance when running.
The emperor penguin (Aptenodytes forsteri) is endemic to Antarctica and is the tallest and heaviest of all living penguin species. It typically measures 115 cm in length and stands around 90 cm tall, with a weight ranging between 22 and 45 kg. Males are heavier than females.
In comparison, the similar-looking king penguin (Aptenodytes patagonicus) is about 25% shorter and weighs 33% less. It breeds on Subantarctic islands, as well as Tierra del Fuego, the Falkland Islands, and other temperate islands of the region.
During the breeding season, male emperor penguins can lose up to 15 kg, as they endure more than two months of fasting while protecting their eggs from the extreme cold.
Like all penguins, emperor penguins are flightless, but they have evolved remarkable adaptations to survive in one of the coldest environments of any breeding bird. Their dense feathers provide up to 90% of their insulation, and they can thermoregulate their core body temperature without increasing their metabolism, conserving energy in the harsh Antarctic climate.
The greater rhea (Rhea americana) is a flightless bird native to South America, also known as the grey rhea, common rhea, or American rhea. It is the largest native bird in the Americas, with an average mass of 23 kg, a length of 134 cm, and a height of around 150 cm.
A small population of greater rheas has established itself in Germany after a male and five females escaped from a farm in August 2000. They survived the winter and began breeding, and today, the population is estimated to be around 600 birds.
Initially classified as domestic animals, they were protected from hunting. However, since 2018, hunting and egg destruction have been permitted to control their numbers.
The lesser rhea (Rhea pennata), also known as Darwin’s rhea, is found in the Altiplano and Patagonia regions of South America. It weighs an average of 13.5 kg and measures about 96 cm in length. Although there is some overlap in weight between the two species, the lesser rhea has shorter legs and a shorter neck, giving it a more compact appearance compared to the taller and more elongated greater rhea.
The wild turkey (Meleagris gallopavo) is one of the largest flying bird species. Weighing between 5 and 11 kg and averaging 124 cm in length, it is surprisingly agile in flight despite its size. However, they tend to stay close to the ground and can only fly short distances, usually no more than 400 metres at a time.
Wild turkeys and domesticated turkeys belong to the same species. Native to North America, wild turkeys got their name from the domestic turkey, which was originally bred from a southern Mexican subspecies. However, early European traders misidentified it as an unrelated species imported from the Ottoman Empire, leading to the misleading name.
Until the 1950s, farmed turkeys closely resembled their wild counterparts. However, to meet growing demand, American farmers selectively bred them for size and faster growth. In the 1930s, an average domestic turkey weighed around 6 kg, whereas today’s farmed turkeys weigh 13.5 kg, more than twice the size.
Unlike their wild relatives, domestic turkeys cannot fly due to their excess weight. Because they do not use their breast muscles for flight, their breast meat is white, whereas wild turkeys have dark breast meat with a richer, game-like flavour.
The trumpeter swan (Cygnus buccinator) is the largest species of waterfowl, with an average weight of 12.7 kg and a length of 138–165 cm. However, males can grow even larger, exceeding 180 cm in total length, and the heaviest recorded individual weighed 17.2 kg. With a wingspan of up to 300 cm, the trumpeter swan holds the title of both the heaviest and longest native bird in North America.
The mute swan (Cygnus olor) is only slightly smaller, with an average weight of 11.87 kg and a length of 100–130 cm. A Polish mute swan cob (C. o. morpha immutabilis), a morph of the mute swan with pure white plumage and pink legs instead of black, holds the record as the heaviest flying bird, weighing 23 kg. However, it is uncertain whether this particular individual was actually capable of flight due to its weight.
The whooper swan (Cygnus cygnus), the Eurasian counterpart of the trumpeter swan, has an average weight of 11.4 kg and measures 140–165 cm in length.
The Kori bustard (Ardeotis kori) is Africa’s largest flying bird and a strong contender for the heaviest living flying bird. It has an average weight of 11.4 kg, a length of 150 cm, and a wingspan of 230–275 cm. However, males in Serengeti National Park are significantly heavier, averaging 12.2 kg, with some individuals reaching 20 kg. There are unverified reports of outsized individuals weighing nearly 40 kg.
Females are much smaller, with an average weight of 5.6 kg, which lowers the overall species average compared to other large bird species that exhibit less pronounced sexual dimorphism in mass.
The great bustard (Otis tarda) averages 10.6 kg in weight and measures 115 cm in length. It breeds in open grasslands across southern and central Europe and Asia, with 60% of the population residing in Spain and Portugal. Once driven to extinction in the UK by trophy hunters in the 1830s, great bustards have since been reintroduced and are now breeding on Salisbury Plain.
The heaviest verified great bustard, recorded in Manchuria, weighed 21 kg, though larger specimens have been reported but remain unverified. The great bustard is also one of the most sexually dimorphic bird species, with adult males in Spain almost 2.5 times the weight of females. The only bird with an even greater size difference between sexes is the green peafowl (Pavo muticus), where males are nearly four times heavier than females.
The wandering albatross (Diomedea exulans), also known as the snowy albatross, white-winged albatross, and goonie, weighs an average of 11.9 kg and measures up to 135 cm in length. Immature birds have been recorded weighing as much as 16.1 kg during their first flights, though they still retain fat reserves that will be shed as they continue to fly.
The species holds the record for the longest wingspan of any living bird, ranging from 2.5 m to 3.5 m. There are unverified reports of wingspans reaching up to 4.22 m and 5.3 m.
Wandering albatrosses spend most of their lives in flight, landing only to breed and feed. Thanks to their long wingspans, they can remain airborne for several hours without flapping, travelling 22 meters for every metre of altitude drop. They are known for their vast ranges, with some individual wandering albatrosses even circumnavigating the Southern Ocean three times in a single year. While the exact distances travelled are difficult to measure, one banded bird was recorded flying 6,000 km in just twelve days.
The Dalmatian pelican (Pelecanus crispus) is the largest member of the pelican family and perhaps the largest freshwater bird in the world, rivalled in length and weight only by swans. They weigh on average 11.5 kg and are 183 cm in length. It has a wingspan similar in size to the great albatrosses and is one of only 4 species of birds having verified wingspans of over 350 cm, the others being the wandering albatross, the southern royal albatross, and the great white pelican.
Dalmatian pelicans are found in lakes, rivers and estuaries in south east Europe, Russia, India and China. During the 20th century the population underwent a drastic decline in numbers most likely due to habitat loss caused by the drainage of wetlands.
13 Responses
wheres big bird from sesame street
Saw a massive pigeon on boro high street the other day. Where’s that on this list eh??? Bollocks
Surprised the bald eagle doesn’t appear here
What about Cassowaries … native to Australia.
Cassowaries are in the list I noticed, Eileen
bro moa is biggest ?? ? ?
I can’t believe the biggest bird is ?
Biggest yes but exstinced it is. Hunded 1400 bc to 500 years ago. They are no longer the biggest bird of our time
Where is peacock
I don’t know ????♂️ to
Never realised penguins were so big. Thought they were small birds until I read this. Is it ok to share on my Facebook? Thanks in advance.
Any info is okay to be shared. But yes I was also surprised that one of the biggest birds are penguins. Flightless yes but they still follow the genetic and evolutionary code of other species of bird.