Ostrich - Longest Legs, Largest Eyes

The Ostrich is the largest living bird and also the heaviest. It is completely flightless but able to cover large distances with speed and stamina on its powerful legs. Due to its size and preferred habitat of open country, it is regularly encountered in wildlife areas where it frequently associates with antelope, zebra and other herbivorous animals.

Vital Statistics

Male Ostriches stand taller than most men, at between 2 and 2.7 metres. They weigh up to 150kg. Females are slightly smaller and lighter. Ostriches have the largest eyes of any terrestrial animal, with a diameter of 50mm (only those of whales, which ironically appear tiny in the gigantic marine mammals, are larger). They have quite a repertoire of noises, including snorts, whistles and a guttural lion-like "booooh".

Varied Diet, No Need to Drink

Ostriches are omnivorous, but feed primarily on seeds, leaves, roots and flowers of various grasses, shrubs and trees. Locusts and other invertebrates are sometimes eaten. Many of the items eaten by Ostriches are unpalatable to other creatures, but are broken down by the bird's 14 metre long intestine. Pebbles and sand are regularly swallowed and stored in the gizzard to help break down tough plant material. Ostrich do not need to drink, as most of their moisture is extracted from succulent plants. On hot days they are able to raise their body temperature by four degrees to reduce water loss.

Breeding Behaviour

Ostriches have quite remarkable breeding behaviour. A dominant male defends a territory of between two and 15 km² (the size depends upon the habitat type). He is usually paired with a single female known as the major hen but will usually also mate with other females within the area. No nest is built but the male excavates a shallow scrape into which the major hen lays a clutch of five to 11 eggs. Minor hens - mated with by the less-than-faithful male - typically add to the clutch with their own eggs (2-6) but play no part in the incubation. The dominant male and major hen share incubation duties between them, with the cryptically-plumaged female on the nest during the day, and the black-plumaged male after dark. Close to 80 eggs may accumulate in a single nest but only 20 or so of these will hatch as this is the approximate number that a single incubating bird can cover. The major hen seems able to distinguish her own eggs from those of other hens and will try to arrange the clutch so that her own eggs are always covered. Banded Mongoose and Egyptian Vultures pose a threat to the eggs, as they are able to crack the shells by repeatedly striking them with small rocks. Adult Ostriches take good care of their young, and will defend them against predators with distraction displays. Interestingly, if two family groups should encounter one another, a clash may break out between the rival adults and the victors often make off with the brood of their opponents!

Predators

Cheetah are probably the main predator of Ostrich, but Lion, Leopard, Wild Dog and Spotted Hyena can also be a threat. Adult males are formidable opponents and have been seen to kick out at, and wound, large predators. For the most part, Ostrich are able to outrun most of their enemies reaching 70km per hour in a short sprint in open country, and 50km per hour over a distance for 30km! Young Ostrich are vulnerable to a whole host of predators, including larger eagles.

Relationship with Mankind

Soft Ostrich feathers (the snow-white tail and wing feathers of the males in particular) were used as adornments by ancient Egyptians and Mesapotamians up to 5000 years ago, and - much more recently in the 18th century - as fashionable avant garde western headgear. The large eggs were valued by early hunter-gatherers, and still are by the modern-day San Bushmen who use them as water containers or make necklaces out of the broken pieces. The skin and meat have been in demand for thousands of years, and Ostrich farms are now viable businesses in several African countries. Today, the demand for Ostrich products is largely met by these commercial farms. Wild populations have however been severely affected by the demand in the past.

Where to see Ostriches on CC Africa properties

Good numbers of Ostrich survive in the Serengeti-Mara ecosystem, so guests at Grumeti River Camp, Klein's Camp, Kichwa Tembo and Siana Springs are all bound to see these impressive birds. A sizeable population also occurs in the Ngorongoro Crater. Fair numbers survive in the dryer parts of the Okavango Delta and may be seen at Nxabega and Sandibe camps. Attempts to reintroduce Ostrich at Phinda have failed (probably due to habitat constraints and predator pressure). Small numbers occur at on the edge of the Kruger National Park. Ostrich survive in the Namib Desert and are among the conspicuous wildlife at Ngala and Sossusvlei Mountain Lodge.

- Duncan Butchart -

Posted: Birds by CC Africa, Date: 21 November 2006