The ostrich is the largest and heaviest living bird, while the Inaccessible Island rail is the smallest living flightless bird. From powerful runners to expert divers, these ten birds and bird groups show how varied life without flight can be.
How we chose these
This editorial selection includes ten remarkable flightless birds and bird groups; the numbers are a display order, not a ranking. We use conservation bodies, museums, zoos and official records for the key facts. Sizes vary between males, females and populations, and population figures are dated.
10. Tasmanian Native-Hen
The Tasmanian native-hen measures about 17–20 inches long (43–51 cm). This flightless rail lives only in Tasmania, where it feeds in open grassy country near fresh water. Brown feathers cover its back and wings, while its underside is slate gray. A yellow bill, red eyes and a long black tail help distinguish it from a domestic hen. It feeds mainly on vegetation, including seeds and leaves, with some insects.
Strong legs make up for its inability to fly. Tasmania’s Parks and Wildlife Service reports speeds of up to 31 mph (50 km/h) and describes the native-hen as a capable swimmer. It is a bird well suited to moving between grassy feeding areas and water, rather than taking to the air.
9. Southern Cassowary
Standing 4–5.6 feet tall (1.2–1.7 m), the southern cassowary is a heavy rainforest bird: females can reach 167 pounds (76 kg), while males reach 121 pounds (55 kg). It lives in northern Queensland and New Guinea. Adults have black feathers; the striking blue is bare skin on the head and neck, accompanied by red wattles. The helmetlike casque on its head has a keratin covering and a spongy interior.
Cassowaries help keep their forests growing. They swallow fruit and disperse its seeds in their droppings, sometimes carrying seeds too large for smaller animals to handle. The male incubates the eggs and cares for the chicks. With its large body, sturdy legs and reduced wings, this bird travels through the rainforest on foot.
8. Inaccessible Island Rail
At about 1.4 ounces (40 g), the Inaccessible Island rail is the smallest living flightless bird. Its chestnut-brown back, gray underside and red eyes belong to a bird found on just one island: Inaccessible Island in the South Atlantic’s Tristan da Cunha group. The island itself is uninhabited.
Inaccessible Island forms part of a UNESCO World Heritage site with neighboring Gough Island. Steep cliffs and difficult landings help explain its name, but remoteness alone cannot protect its wildlife. Introduced species are a major concern for these island ecosystems, so strict biosecurity is essential. For this tiny rail, protecting its one island means protecting its entire natural range.
7. Takahē
The takahē is the world’s largest living rail, weighing about 5.1–8.4 pounds (2.3–3.8 kg). Its deep-blue head and breast, green back, red bill and red legs make it one of New Zealand’s most distinctive birds. It is larger and heavier than the similar-looking pūkeko, which can fly. Takahē use their strong bills to eat the soft bases of grasses and sedges, and their small wings still play a part in displays.
Rediscovered in Fiordland’s Murchison Mountains in 1948, takahē have depended on intensive conservation work. New Zealand classifies them as Threatened–Nationally Vulnerable. In May 2026, the Department of Conservation reported just over 500 birds. Moving birds to protected sites and controlling introduced predators, including stoats, remain central to their recovery.
6. Guam Rail
The Guam rail, or ko’ko’, is about 11 inches long (28 cm) and weighs 7–12 ounces (200–350 g). Its narrow body helps it move through dense vegetation, but flightlessness left it vulnerable to the introduced brown tree snake. The bird disappeared from the wild on Guam in 1987; captive breeding and releases kept the species alive. On December 10, 2019, IUCN announced its move from Extinct in the Wild to Critically Endangered.
The recovery remains fragile. A US Fish and Wildlife Service review using 2025 data estimated 22–48 wild birds, all on Cocos Island, plus about 100 in captivity. Surveys on Rota detected no rails in 2024 or 2025. Brown tree snakes were documented again on Cocos in 2020, making continued snake control crucial. These dated estimates show why the return to the wild is a milestone rather than the end of the conservation effort.
5. Flightless Cormorant
The flightless cormorant averages about 35 inches long (90 cm), with larger birds reaching 39 inches (1 m). Found only on Isabela and Fernandina in the Galápagos, it is the only cormorant that cannot fly. Small wings and powerful swimming legs give it an unusual appearance among the islands’ endemic animals. Underwater, it holds its wings close to its body and uses its feet to pursue fish and other prey.
On shore, it often spreads those short wings to dry, much like flying cormorants. Its diet includes fish, eels and octopuses from coastal waters. The species is classified as Vulnerable; fishing gear can entangle birds, while warmer seas during El Niño events can reduce their food supply. Its small island range makes changes in the surrounding ocean especially consequential.
4. Kiwi
New Zealand has five kiwi species: brown kiwi, great spotted kiwi, little spotted kiwi, rowi and tokoeka. The smallest, the little spotted kiwi, stands about 14–18 inches tall (35–45 cm). Kiwi have hairlike feathers and tiny wings hidden beneath them. Their long bills carry nostrils near the tip, helping them smell food as they probe for worms and other small animals.
Kiwi also have a relatively low body temperature for birds, around 100°F (38°C). Most are active at night, using their strong legs to move around their territories. Their conservation status varies by species and population; they are not all in the same threatened category. Introduced predators remain a major threat: stoats kill chicks, while dogs can kill adults. Predator control and protected habitats are therefore vital to kiwi recovery.
3. Ostrich
The ostrich is the largest and heaviest living bird. Males stand about 6.9–9 feet tall (2.1–2.7 m) and weigh 220–287 pounds (100–130 kg). Their long legs carry them at sprinting speeds of up to 43 mph (70 km/h). Unlike other birds, ostriches have just two toes on each foot, a distinctive feature of these fast runners.
Although it cannot lift that enormous body into the air, an ostrich still puts its wings to use. It spreads them for balance while running and changing direction, and uses them in courtship displays. Males have contrasting black-and-white plumage, while females are generally brown. Among the world’s largest living birds, the ostrich is the clearest example of a body built for speed on land.
2. Kākāpō
The kākāpō is the heaviest parrot, with males weighing up to 8.8 pounds (4 kg), and the world’s only flightless parrot. This nocturnal New Zealand bird has moss-green plumage and a rounded, owllike face. Its coloring helps it blend into vegetation, making it a very different sight from many brightly colored parrot species.
As of September 2026, the population stood at 325, including 90 newly counted chicks. New Zealand lists the kākāpō as Nationally Critical, and the birds receive intensive management at protected sites. Introduced predators, disease and low egg-hatching success are among the challenges facing their recovery. Their survival depends on sustained breeding, monitoring and habitat protection.
1. Penguins
There are 18 penguin species, according to the Australian Antarctic Division. All are flightless, with wings shaped into flippers for swimming. The largest is the emperor penguin: adults can weigh about 88 pounds (40 kg) at the start of the breeding season. Dense feathers and a layer of fat help emperors retain heat, while their close huddles provide shelter through the Antarctic winter.
Breeding on sea ice brings a growing risk. IUCN moved the emperor penguin to Endangered in April 2026, citing the effects of climate change. When sea ice breaks up before chicks develop waterproof feathers, breeding colonies can suffer heavy losses. Adults also need stable ice during their annual molt. The ice that supports their lives on land is therefore as important as the water where they hunt.
