There are over 60 species of flightless birds living around the world today These flightless birds are bird species that through evolution have lost the ability to fly, whilst carving out a new evolutionary niche.
It’s a valid question to ask why birds would ever give up the ability to fly, given how the many advantages flying gives over terrestrial animals. Flying birds are able to quickly escape potential threats, nest in places out of reach of predators, and easily cover long distances in search of mates, food, water, and a better climate.
The thinking as to how birds became flightless is that when food was readily available, predators were absent and the climate moderate year-round, birds had no reason to fly. Over time their muscles deteriorated through lack of use until they were eventually grounded permanently.
Flightless birds all have what are known as vestigial wings. (A vestigial feature is one that had a necessary function for a species’ ancestors, but is not particularly important for modern species.) The wings of a flightless bird are anatomical, rudimentary wings, but are so small or powerless as to be useless to enable flight. They are not completely useless however, and used for balance during running, as well as in courtship displays.
With the lack of flight, many bird species experienced a big increase in size, along with strong legs to support the extra weight. So much so that flightless birds make up the heaviest and largest birds on the planet.
With this context in mind, in the below article we look at 17 iconic species of flightless birds from around the world, listing them in reverse size order:
Up to 0.5 meters tall and 2 kg
There are five species of flightless kiwis – all brown chicken-sized birds endemic to New Zealand. Like all other flightless birds kiwis have ‘vestigial wings’, and their feathers are hairlike and soft. Unusually for birds, kiwis’ nostrils are on the tip of their bills rather than at the base. Unique kiwi fact, females lay eggs that are up to 0.5 kgs – the biggest egg relative to body size of any living species.
Takahe (Porphyrio hochstetteri)
Up to 0.5 meters tall and 4.2 kg
As with many of New Zealand’s flightless birds, the takahe was thought to be extinct from the late 1800s, until it was rediscovered alive and well in 1948. This small-medium sized ground-dwelling bird has short wings, large feet with long toes, along with bright coloration consisting of a red and blue plumage and a red bill and legs.
Weka (Gallirallus australis)
Up to 0.6 meters tall and 1.6 kg
The brown, chicken-sized weka bird is an unremarkable flightless bird endemic to New Zealand. They were an important food source for native New Zealanders and European settlers, and their numbers have declined dramatically over the past few hundred years. Although wekas are not able to fly, they do possess some serious swimming skills!
Kakapo (Strigops habroptilus)
Up to 0.6 meters tall and 4 kg
The kakapo is another New Zealand flightless bird, that also goes by the name of the owl parrot and the mighty moss chicken. It’s an unusual-looking nocturnal bird with finely blotched yellow-green plumage that allows it to camouflage as a shrub in its ground nest. Their small but heavy bodies give them the title of the world’s heaviest parrot, and their special skill is a super-loud booming call that can be heard up to 1 kilometer away.
Macaroni Penguins (Eudyptes chrysolophus)
Up to 0.69 meters tall and 6.4 kg
As with birds generally, most penguin species mate for life. Marconi penguins (also known as Royal Penguins) take loving relationships to a new level, however, performing an ‘ecstatic display’ when they see each other after being apart, puffing up their chests, swinging their heads around, and making a gurgling sound. Once their chick is hatched, the father stays with the offspring while the mother heads off to hunt for food for the family.
Dwarf Cassowary (Casuarius bennetti)
Up to 1 meter tall and 13 kg
The smallest of the cassowary species, but still big enough to make this list, the dwarf cassowary (Casuarius bennetti) also goes by the names of Bennett’s cassowary, little cassowary, mountain cassowary, and mooruk. Dwarf cassowaries are only found in mountain forests up to elevations of 3,300 meters in New Guinea, New Britain, and Yapen Island
King Penguin (Aptenodytes patagonicus)
Up to 1 meter tall and 18 kg
King penguins (Aptenodytes patagonicus) live on selected islands in the outer reaches of Antarctica, as well as Tierra del Fuego on the tip of the South American continent. They are the second species of penguins on this list, reaching heights of 1 meter and weights of 18 kilograms – around the same weight as the largest flying birds.
Lesser Rhea (Rhea pennata)
Up to 1 meter tall and 20 kg
The lesser rhea – or Darwin’s rhea – (Rhea pennata), stands up to 1 meter tall and weighs in at around 20 kilograms. It’s found in South America, roaming both the Andean altiplano and the open Patagonian steppe. Lesser rheas occur singly or in small groups, and males take care of their young birds.
Domestic Turkey (Meleagris gallopavo f. domestica)
Up to 1.3 meters tall and 39 kg
Wild and domestic turkeys are the same species, native to North America. Unlike wild turkeys, however, domestic turkeys (Meleagris gallopavo f. domestica) are not able to fly as they have been selectively bred to be so heavy. Because they’re unable to fly they don’t use their breast muscles, meaning their breast meat is white – unlike wild turkeys which have dark, gamey breast meat.
Emperor Penguin (Aptenodytes forsteri)
Up to 1.3 meters tall and 24 kg
Emperor penguins (Aptenodytes forsteri) are the tallest and heaviest of all penguins, and are found only in Antarctica. Male and female emperor penguins are flightless and similar in size and colouring to females, but perform very different functions in the breeding season.
Hundreds of male Emperor penguins huddle together to protect their eggs from the extreme cold for two months of the dark Antarctic winter as the females head out to sea to hunt. During this time males lose close to half of their body weight.
Up to 1.5 meters tall and 35 kg
Greater rheas (Rhea americana) are the largest birds in the Americas, native to Argentina, Bolivia, Brazil, Paraguay, and Uruguay. As with so many birds on this list, the greater rhea is flightless and and extremely fast bird, able to reach 35 kilometers per hour using their long, powerful legs.
Along with their high speeds, they protect themselves from predators by gathering in flocks of up to 100 birds during the non-breeding season.
Up to 1.7 meters tall and 70 kg
A smaller cousin of the southern cassowary, the northern cassowary (Casuarius unappendiculatus) is endemic to northern New Guinea. The females of the species are larger than the males, weighing up to 70 kilograms and standing 1.7 meters tall. Despite their stocky build, the northern cassowary – also known as the single or one-wattled cassowary or gold-necked cassowary – can run in bursts at 50 kilometers an hour.
Southern Cassowary (Casuarius casuarius)
Up to 1.8 meters tall and 85 kg
The southern cassowary (Casuarius casuarius) is a huge, flightless, black bird found in north-eastern Australia, Indonesia, and New Guinea. One of three cassowary species, they also go by the names double-wattled cassowary, Australian cassowary, and two-wattled cassowary.
As well as being the fourth-largest bird in the world, the southern cassowary has a claim to be the most dangerous bird on Earth. Each of their large feet has sharp 13-centimeters claws they use to kick out in defense, and have been known to kill humans.
Emu (Dromaius novaehollandiae)
Up to 1.9 meters tall and 60 kg
Australia’s emus (Dromaius novaehollandiae) are like a shaggier, slightly smaller ostrich, and like ostriches are not built for flight. The females of the species are larger than the males and can reach 1.9 meters tall – which makes them the third largest bird in the world. Their speed is impressive too, able to reach 48 kilometers per hour, using their three-toed feet and tiny wings to keep them stable when running.
Somali ostrich (Struthio molybdophanes)
Up to 2.7 meters tall and 130 kg
The Somali ostrich (Struthio molybdophanes) was considered a sub-species of common ostrich until 2014, when it was assigned as a distinct species. Native to Somalia and parts of Ethiopia and Kenya, the Somali ostrich is generally a little lighter than it’s common ostrich cousin, but is just as impressive with its running speed, and is able to cover 5 meters in a single stride!
Common Ostrich (Struthio camelus)
Up to 2.8 meters tall and 160 kg
The common ostrich is the tallest, heaviest, and all-round biggest bird in the world, with an average height of over 2 meters (sometimes as tall as 2.7 meters) and a weight of up to 160 kg. At this size, the ostrich is, of course, flightless, but can outrun plenty of animals with its top speed of 69 km per hour.
Their long, powerful legs double up as defensive weapons which pack a powerful kick to would-be predators. Fun ostrich fact – they are able to survive without water for days, generating water internally and extracting water from vegetation.
Bonus semi-flightless birds
Helmeted Guineafowl (Numida meleagris)
Guinea fowl are found in the savannas and grasslands of Africa, with their distinctive bright blue head and neck and hanging red wattle. They are terrestrial birds (though can fly and glide short distances), preferring to run rather than fly when alarmed.
They’re often seen scratching around in loose soil, like chickens, looking for food such as seeds, fruits, greens, snails, spiders, worms, and insects. They also take on larger prey with their strong claws such as frogs and toads, lizards, small snakes, and small mammals. These birds are able to fly, but spend the vast majority of their lives on the ground, only taking to the air when there is imminent danger.
And that’s your lot for our round-up of the most iconic flightless birds. Have you had the opportunity to see any of these stunning avians in real life? Please share your experiences in the comments section below!