Ostrich

Quick Take

• Aristotle studied the ostrich and still couldn't decide what it was, and the reason for his uncertainty reveals just how unlike any other creature on Earth it really is. Explore its classification →
• The popular image of an ostrich burying its head in sand is wrong, and what it actually does instead is far stranger. See the head-burying myth →
• An ostrich's foot can kill a lion, yet most predators don't even bother trying to outrun one. The reason why reveals a cunning ambush strategy. Meet the ostrich's predators →
• In an ostrich's communal nest, not every egg has an equal shot at survival. One bird holds a hidden advantage over all the others. Discover the communal nest →

The ostrich looks like an unusual chimera cooked up in a lab. When writing about it, the Greek philosopher Aristotle did not know whether to classify it as a bird or a mammal. The ostrich belongs to an unusual group of flightless birds well-adapted for life on the ground. Years of hunting almost drove them to extinction, but numbers have recovered sufficiently so that the ostrich now roams the plains of Africa once again.

Incredible Ostrich Facts

• The ostrich eye, at around 2 inches across, is the largest of any known land animal worldwide.
• The ostrich is the only bird with two toes. Every other type of bird has three or four.
• The ostrich was once hunted or farmed in large numbers for its feathers, dating back to ancient Egypt, Babylon, and Assyria. These feathers were used by royalty, upper-class women, and even medieval knights. By 1913, as hunting subsided, more than a million ostriches were raised on farms. However, a fall in the popularity of ostrich feathers caused the farms to decline as well.

Scientific Name and Species

The scientific name of the ostrich genus is Struthio, derived from the Ancient Greek term for the ostrich and the sparrow. Struthio camelus is also known simply as the common ostrich. (Camelus, as you might expect, is a Latin word meaning camel, derived from the Greek kamelos, which was itself borrowed from a Semitic language, perhaps named for the animal’s ability to go long periods without water.) 

There are two species of ostrich: the Somali ostrich (Struthio molybdophanes) and the common ostrich (Struthio camelus). Subspecies of the common ostrich include the Masai ostrich (a pink-skinned variety also called East African ostrich), the nominative ostrich (red-necked ostrich or Barbary ostrich), the South African ostrich (Black-necked ostrich or Cape ostrich), and the Arabian ostrich (a Syrian or Middle Eastern ostrich, now extinct). 

The ostrich is an example of a ratite, a member of a group of distantly related large flightless birds, including the kiwi, the emu, and the rhea. It was once assumed that the ratites belonged to a single order. However, genetic analysis suggests that these birds had separate evolutionary lineages, so they were placed in different orders entirely. The ostrich is now the only living member of its family and order.

Evolution

The earliest ostrich fossils date back around 20 to 25 million years. Around 12 million years ago, ostriches evolved to the larger size they are known for. This was also when they began to leave Africa for the rest of Eurasia. All of these non-African species are now extinct.

One interesting trait that the ostrich developed in its evolution is its two toes, whereas most birds have four. The two-toed structure of this ratite helps the ostrich run at high speeds. It’s believed that ostriches evolved in the steppes of Central Asia and then spread to Africa 20 million years ago. In the early Cenozoic (40 million years ago), their ancestors inhabited much of the Northern Hemisphere.

Little is known about their early ancestors or why these birds developed their large size. Their closest relative is the elephant bird, an extinct species that once lived on the island of Madagascar. It is speculated that early kiwis could fly, which would explain why they ended up so geographically distant from their much larger relatives.

Appearance

The ostrich is easily distinguishable from all other birds by its sheer size. Dressed in soft black and white plumage, the male ostrich stands up to 9 feet high and weighs up to 320 pounds. The female, which measures up to 6 feet tall and weighs up to 242 pounds, is much smaller. She and her young chicks have more gray-brown feathers around the body. Regardless of sex, the ostrich’s long, sinewy neck, head, and legs are almost completely bare except for a thin layer of down. The skin is either pink or gray, but the exact colors and patterns may vary by the subspecies.

Given the ostrich’s large size, it’s no surprise that the wings are completely incapable of flight. Evidence suggests that the wings, along with the tail, help the bird maintain balance and court females. The incredibly soft feathers, which lack the waterproof quality of many other birds, hang rather loosely off the body.

Behavior

The ostrich is a social species that congregates in flocks of around 10 birds during the breeding season and smaller groups of two to five members throughout the rest of the year. These flocks are often seen in the company of other grazing animals like antelopes and zebras. However, this tolerance for other species doesn’t necessarily extend to different flocks since these birds will guard their territory fiercely from outside intruders. Unlike the rich sounds of many other birds, the ostrich can make a roar and a sharp hiss, often used by males to intimidate each other. Ostriches also make booming sounds or low drumming calls when agitated.

These birds spend almost all day grazing and foraging for food, which is abundant in the African savannas. Although they can go for long periods without liquids, ostriches appear to have a strong affinity for large bodies of water, where they often take baths to clean themselves off.

Contrary to popular myth, ostriches do not bury their heads in the sand when threatened; rather, they press their heads and necks flat against the ground, perhaps to avoid detection. Their first instinct is to run away or hide from danger, but that does not mean the bird lacks defenses. The ostrich has a rather vicious clawed foot that can kill a predator as large as a lion.

Habitat

These birds inhabit the savannas, woodlands, and deserts of Africa. They are endemic to a large strip of land between Western Africa, the Horn of Africa, and Southern Africa. The savanna sometimes provides brush cover for the ostrich to hide in, but when cover is sparse, the bird relies on its speed and agility to evade predators.

Diet and Digestion

These birds enjoy an omnivorous diet heavy in plant material. The bird’s diet comprises seeds, grass, fruits, and flowers. It sometimes supplements this with insects, reptiles, or other meat left over by carnivores. 

This bird has an intestinal tract more than 70 feet long, enabling it to extract as many nutrients as possible. It swallows stones and sand along with food, then grinds everything in its gizzard. These birds can also survive without a single drop of water for several days. They can lose up to a quarter of their body weight in water before they need to drink again.

Predators and Threats

The biggest threat to these birds has been human hunting. The drive to harvest their feathers almost led to the ostrich’s extinction in the 19th century. As ostrich farming became more common, this practice lost some appeal. However, hunting, habitat loss, and even predation still pose some risks to the ostrich.

Despite its formidable size, the bird is threatened by all kinds of carnivores, including lions, cheetahs, leopards, hyenas, and African hunting dogs. Vultures, warthogs, and mongooses also raid nests for their eggs. Except for the cheetah, most predators cannot keep up with the ostrich’s impressive speed, so they wait to ambush the unsuspecting bird.

Reproduction, Babies, and Lifespan

The breeding season lasts from March to September of each year. The male performs an elaborate dance in which he bows toward the ground and shakes his feathers — first one wing, then the other — while his tail bobs up and down. The dance is intended to display the male’s strength and health so that the female can assess his fitness. The most territorial male will mate with groups of three to five hens at a time, but forms a pair bond only with the most dominant hen. Other males will also have the opportunity to mate with the remaining females.

Together, the fertilized females deposit their eggs into a communal nest — simply a hole dug in the ground. The dominant hen places her eggs at the center, giving them the best chance at survival, but all of the eggs have a better chance to survive than if they were incubated in a separate nest. Each female can lay seven to 10 eggs, but the communal nest can hold up to 60 eggs. Weighing more than 3 pounds, these eggs are the largest of any species on the planet. They are nearly as large as some dinosaur eggs. Males and females take turns guarding the nest. The group’s females watch over it during the day, while the males take over at night.

After an incubation period of 42 to 46 days, the chicks will emerge from the eggs with stiff down, measuring about the same size as a chicken. After they leave the nest, the parents will shelter the chicks to protect them from harsh sunlight or rain. When threatened, the male will attempt to distract the predator with a display of loud noises and an outstretched neck, while the females and chicks attempt to find cover.

The baby bird grows quickly; at about six months, it is almost the same size as the adult bird. It reaches sexual maturity after three to four years, which is relatively late compared to most birds. The regular lifespan of these birds is about 30 to 40 years in the wild and about 50 years in captivity.

Population

The IUCN Red List considers the common ostrich a species of least concern, while the Somali ostrich is potentially vulnerable to extinction. Both species appear to be decreasing slightly in number, and it is estimated that no more than 150,000 ostriches remain in the wild.