Ostrich

Physical features

• Ostriches are the largest and heaviest living species of bird.

• They are sexually dimorphic; males and females differ in coloration and size. Sexually mature males (2-4 years) reach between 6 - 9 feet (1.8-2.7 meters) in height and 198-242 pounds (90-100 kilograms) , while females reach maturity about 6 months earlier and attain heights of 6.5 feet (1.7-2 meters) and weigh 220-287 pounds (100-130 kilograms). Male coloration consists of bright black/white contrasts while females are usually more grey and drab. Males also have more prominent tail plumage.

• Feathers are soft since ostrich are flightless and don’t require rigid airfoil feathers. Feathers are also not waterproof. Wings are used for insulation, shade for chicks, and mating displays. Two “fingers” protruding from leading edge of wings are clawed.

• The ostrich is adapted for running of speeds of over 40 mph rather than for flight, and they lack a keel (an extension of the sternum that provides an anchor for wing muscles).

• They are the only bird to have two toes on each foot. Other birds have three or four. This gives greater strength to the foot. They can kick to defend themselves with their powerful legs and feet, but their first defense is to run.

Diet: Omnivore

• Wild – Plant matter, seeds, occasional insects like locusts, other invertebrates, and sometimes small vertebrates

• Zoo – Ostrich pellet diet (which contains vegetables and grain) in addition to fresh vegetables, greens, fruit; they will also eat leaves and grasses

• Ostriches can go without water for many days, conserving the moisture found in plant matter, but they do enjoy water and will bathe when they have the opportunity. They always have water available at Zoo Atlanta.

• They will swallow small stones and pebbles (gastroliths) to aid in grinding and digestion. Adults typically carry around 2 pounds (1 kilogram) of stones at any given time.

Reproduction

• Males compete for groups of 3-5 hens, using hisses and wing displays. The male will mate with the dominant hen in the group and they will incubate the eggs and care for chicks once they hatch. The other females in the group may mate with the male or may also mate with other lone males that are wandering.

• Eggs are laid in a single communal nest in a shallow pit scraped into the ground. The dominant female lays her eggs in the middle of the nest to ensure their survival. In some regions, a female may nest singly.

• Mating season begins in March/April and can last until September.

• Ostrich eggs are about 6” x 5”, weigh around 3 pounds, and have the volume of over 20 chicken eggs. They are the largest of all eggs, though smallest in ratio to body size of the bird, at only 1% of the female’s body weight.

• A hen can lay 7-10 eggs in a clutch. Communal nests used by multiple females can contain 15-60 eggs. Incubation period is 42-46 days.

• Females incubate the nest during day, and males incubate the nest at night (their coloration is camouflage).

• An ostrich chick is about the same size as a chicken but can grow 1 foot per month and is close to its parents’ size by 6 months of age.

Interpretive Information

• Ostriches are social and live in nomadic groups of 5-50 individuals. They will forage among herds of large mammals like zebras and wildebeests.

• They are part of the ratite group, which includes other flightless birds such as rheas, cassowaries, emus, and kiwi. The flighted tinamous are also related to this group of birds, implying that each lineage independently became flightless.

• In desert areas some African tribes traditionally used ostrich egg shells as containers for water.

• A popular myth is that ostriches bury their head in the sand. When they are sitting on their nests, they will stretch out their long necks out on the ground to hide from danger. From a distance, it can look as if they have buried their heads in the sand, but this is a myth. If they buried their heads in the sand, they would not be able to breathe!

• Ostriches have the largest eye out of any land animal at 2 inches (5 centimeters) across.

• Ostriches are raised on farms for their meat, leather, eggs, and feathers.

• There are two species of ostrich: common ostrich and Somali ostrich. There are four subspecies of common ostrich: The critically endangered North African ostrich, plus south African ostrich, Masai ostrich, and the now-extinct Arabian ostrich. The Somali ostrich was once thought of as another subspecies but has since been identified as its own separate species.

• Though usually silent, they are capable of making a number of vocalizations including a deep booming sound from territorial males during breeding season to attract females and as a warning to other males, a softer sounding contact call, hisses, and beak snapping.

• Ostriches, like other birds, cannot sweat. They survive in very hot climates and will pant to help regulate body temperature.

Updated July 2019