[22] The long neck and legs keep their head up to 2.8 m (9 ft 2 in) above the ground, and their eyes are said to be the largest of any land vertebrate – 50 mm (2.0 in) in diameter[24] – helping them to see predators at a great distance.

[45][46] However, a study analysing the postcranial skeleton of all living and recently extinct species and subspecies of ostriches appeared to validate S. c. spatzi based on its unique skeletal proportions.

[15] Today common ostriches prefer open land and are native to the savannas and Sahel of Africa, both north and south of the equatorial forest zone.

[15] During breeding season and sometimes during extreme rainless periods ostriches live in nomadic groups of five to 100 birds (led by a top hen) that often travel together with other grazing animals, such as zebras or antelopes.

[56][57] When lying down and hiding from predators, the birds lay their heads and necks flat on the ground, making them appear like a mound of earth from a distance, aided by the heat haze in their hot, dry habitat.

[61] They mainly feed on seeds, shrubs, grass, fruit, and flowers;[15][22] occasionally they also eat insects such as locusts, small reptiles such as lizards, and animal remains left by carnivorous predators.

[65] The female common ostrich lays her fertilized eggs in a single communal nest, a simple pit, 30 to 60 cm (12 to 24 in) deep and 3 m (9.8 ft) wide,[66] scraped in the ground by the male.

[70] As a flightless species in the rich biozone of the African savanna, the common ostrich faces a variety of formidable predators throughout its life cycle.

[80] Overall, due to their speed, vigilance, and possibly dangerous kick, ostriches are usually avoided by most predators, including lions, leopards, wild dogs, and cheetahs.

The use of air sacs forms the basis for the three main avian respiratory characteristics: Inhalation begins at the mouth and the nostrils located at the front of the beak.

The common ostrich air sacs play a key role in respiration, since they are capacious, and increase surface area (as described by the Fick Principle).

[90] To compensate for the large "dead" space, the common ostrich trachea lacks valves to allow faster inspiratory air flow.

[88] Hot, dry, and moisture lacking properties of the common ostrich respiratory medium affect oxygen's diffusion rate (Henry's Law).

[86] The use of such mechanisms demonstrates an increase in the later stages of lung development, along with elaborate parabronchial vasculature, and reorientation of the gas exchange blood capillaries to establish the crosscurrent system at the blood-gas barrier.

The deep branches of the coronary arteries found within the heart tissue are small and supply the interventricular and right atrioventricular valve with blood nutrients for which to carry out their processes.

[99] The majority of phosphate concentration switches from 2,3- DPG to IPP, suggesting the result of the overall low oxygen affinity is due to these varying polyphosphates.

[99] Concerning immunological adaptation, it was discovered that wild common ostriches have a pronounced non-specific immunity defense, with blood content reflecting high values of lysosome and phagocyte cells in medium.

This is in contrast to domesticated ostriches, who in captivity develop high concentration of immunoglobulin antibodies in their circulation, indicating an acquired immunological response.

[87] Common ostriches have two kidneys, which are chocolate brown in color, are granular in texture, and lie in a depression in the pelvic cavity of the dorsal wall.

Hence, common ostriches drink relatively large volumes of water daily and excrete generous quantities of highly concentrated urine.

Thus in response to the dehydration, ostrich kidneys secrete small amounts of very viscous glomerular filtrates that have not been broken down and return them to the circulatory system through blood vessels.

[87] In comparison to smaller birds ostriches have a lower evaporative water loss resulting from their small body surface area per unit weight.

[90] Both of these antidiuretic hormones work together to maintain water levels in the body that would normally be lost due to the osmotic stress of the arid environment.

[87] Common ostriches display a feather fluffing behavior that aids them in thermoregulation by regulating convective heat loss at high ambient temperatures.

[106] This ostrich will also cover its legs to reduce heat loss to the environment, along with undergoing piloerection and shivering when faced with low ambient temperatures.

[88] As ambient air becomes hotter, additional evaporation can take place lower in the trachea making its way to the posterior sacs, shunting the lung surface.

[15][115][116] The presence of such eggshells with engraved hatched symbols dating from the Howiesons Poort period of the Middle Stone Age at Diepkloof Rock Shelter in South Africa suggests common ostriches were an important part of human life as early as 60,000 BP.

[119] This myth likely began with Pliny the Elder (23–79 CE), who wrote that ostriches "imagine, when they have thrust their head and neck into a bush, that the whole of their body is concealed.

[125] Common ostrich meat tastes similar to lean beef and is low in fat and cholesterol, as well as high in calcium, protein, and iron.

Similar behaviors are noted in captive or domesticated common ostriches, which retain the same natural instincts and can occasionally respond aggressively to stress.