Ostriches : Things you might not about these big birds. The biggest birds on the planet

Among all the species of birds, most of them which can fly, we don't often see birds that are very huge in size. The largest flying bird on the planet, which is the Wandering Albatross, is surely large, but not that large as compared to the bird which we are going to talk about today. The "Ostrich" holds the title of the biggest, tallest and heaviest bird on the planet, although ostriches can't fly as we all know. Let's learn about various features, characteristics, their huge size and  lifecycle of these birds as well as about what makes them flightless. let's start.

Struthio camelus (Common Ostrich)

General Info

Ostriches are large-sized flightless omnivorous birds which are known for their big body structure and their inability to fly. They are most commonly found in the continent of Africa in dry parts of woodlands and savannas. However, they can be also found in some Asian and Australian countries like Iraq, Iran, Southern Australia and Saudi Arabia. Their are 2 known and living species of ostriches with one of them having 4 sub-species in it. These are:

1) Common Ostriches

• Northern African Ostriches

• East African Ostriches (Masai Ostriches)

• Middle-eastern Ostriches (Arabian Ostriches) (extinct)

• Southern African Ostriches 

2) Somali Ostriches

The exact population of these birds is not known although it is said that their population is decreasing. Among the common ostriches, the Northern African, East African Ostriches (Masai Ostriches) and the Southern African ostriches are stable in population and are at the spot of "Least Concerned (LC)" species on the IUCN red list ,while the East African Ostriches (Masai Ostriches) are extinct. As for the Somali Ostriches, they are low on population and are currently on the spot of "Vulnerable (VU)" species on the IUCN red list. Also the average lifespan of ostriches is from 40 to 45 years but can also live from 50 to 60 years, depending upon the species, region and type of environment (in the wild or in captivity).

Physical Characteristics

Ostriches are very large birds with a long neck, strong and long legs and a small head. Their height can be anywhere from 5 ft 7 inches to 9 ft 2 inches (~1.7 to 2.8 meters) and weigh from 143.3 to 319.6 pounds (65 to 145 Kg). Both the height and the weight depends upon the type of species and their gender (as males are slightly taller and heavier than the females.) As for their appearance, the males and females also look slightly different from each other with the males having black wings and white underparts and the females having light brown wings and white underparts.

Northern African Ostrich (top left), Southern African Ostrich (middle on the top), East African Ostrich or Masai Ostrich (top right), Middle-eastern Ostrich or Arabian ostrich (bottom left) and the Somali Ostrich (bottom right)  

Their beak is flat and broad, with a rounded tip. The bird has just two toes on each foot (most birds have four), with the nail on the larger, inner toe and the outer toe has no nail. They have 50–60 tail feathers, and their wings have 16 primary, four alular and 20–23 secondary feathers.

The ostrich has no crop, and it also lacks a gallbladder. They have three stomachs, and the caecum is 28 inches (71 cm) long. They also have unique pubic bones that are fused to hold their gut. Unlike most birds, the males have a copulatory organ, which is retractable and 8 inches (20 cm) long.

With the help of their long and strong legs, they become the fastest birds on land with an average speed of 44.74 miles per hour (72 Km/h) to a maximum speed of 60 miles per hour (96.6 Km/h). They are mostly seen running at a speed of around 30 miles per hour (48.28 Km/h) without any problem and rarely run at their maximum speed, and if they do, it only lasts for a short period of time. Also, while running at peak speed they take long strides measuring from 10 to 16 feet (3.04 to 4.87 meters) in length.

Behavior and Lifestyle

Ostriches are generally not aggressive and tends to escape when they sense danger. In case of humans, this is also true as they quickly run away if they are spooked or disturbed. However, they can be very aggressive specially in those cases where they are cornered. With the help of their strong and long legs, they can unleash a devastating kick towards the danger which can cause serious injury or even death.

They usually live solitary or in a pair. Only 16% of common ostrich sightings were of more than two birds. 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 like wildebeest, antelopes and zebras. 

As for their diet, they mostly eat grass, shrubs, fruits, flowers and seeds and sometimes also eats insects. They have a very solid inner system and can survive without water for many days or sometime even more than 2 weeks. Due to dehydration, they can loose 25% of their body weight and can still survive even after that.

Biological Features

Metabolism

They have a very stable and well designed metabolic system which helps them to maintain the necessary energy requirements of their body with the help of oxidation process of their absorbed nutrients.

Heat regulation and breathing

Since ostriches has no sweat glands, they completely rely on panting (quick or short breaths) to increase the evaporative heat and ultimately loosing body heat from their respiratory surfaces. 

Kidneys

Being capable of surviving without water for days does not mean that they don't drink water often. In actual, they drink large quantity of water when it is readily available. That's why they have large kidneys to filter large amount of water which further leads to excretion of highly concentrated urine.

Stomach and Digestion 

Ostriches don't have teeth, therefore they swallow pebbles and stones to use them as grinders inside their stomachs. They have 3 stomach which is used to digest and metabolize the tough plant matter properly.

Heart

They have a large conical shaped heart which uses a closed and contractile chamber system. The structure of ostrich's heart is quite complex which has a double circulatory plan in place possessing both a pulmonary circuit and systemic circuit.

Composition of blood

The red blood cells (RBC) in their blood are 3 times bigger than that of human beings. Also, the red blood cell count per unit volume in the ostrich is about 40% of that of a human.

Reproduction

Ostriches reach the stage of sexual maturity at the age of 2 to 4 years old. The females mature about six months earlier than males. As with other birds, an individual may reproduce several times over its lifetime. The mating season begins in the month of March or April and ends sometime before the month of September. The mating process differs in different geographical regions.

Territorial males typically get active in the defense of their territory and harem of two to seven hens. The successful male may then mate with several females in the area, but will only form a pair bond with only one “major” female. They use certain gestures and movements to attract the females. The males performs with the help his wings, alternating wing beats, until he attracts a mate. They will go to the mating area and he will maintain privacy by driving away all intruders. They graze until their behavior is synchronized, then the feeding becomes secondary and the process takes on a ritualistic appearance. The male will then excitedly flap alternate wings again, and start poking on the ground with his bill. He will then violently flap his wings to symbolically clear out a nest in the soil. Then, while the hen (female) runs a circle around him with lowered wings, he will wind his head in a spiral motion. She will drop to the ground and he will mount for copulation.

The female common ostrich lays her fertilized eggs in a single communal nest, a simple pit, scraped in the ground by the male. The dominant female lays her eggs first, and when it is time to cover them for incubation she discards extra eggs from the weaker females, leaving about 20 in most cases. A female common ostrich can distinguish her own eggs from the others in a communal nest. Ostrich eggs are the largest of all eggs, though they are actually the smallest eggs relative to the size of the adult bird – on average they are 5.9 inches (15 cm) long, 5.1 inches (13 cm) wide, and weigh 3.08 pounds (1.4 Kg) on an average and ranges from 2.42 to 4.30 pounds (~ 1.1 to 1.95 Kg).

The eggs are incubated by the females by day and by the males by night. This uses the coloration of the two sexes to escape detection of the nest, as the drab female blends in with the sand, while the black male is nearly undetectable in the night. The incubation period is 35 to 45 days, which is rather short compared to other flightless birds. This is believed to be the case due to the high rate of predation. Typically, the male defends the hatchlings and teaches them to feed, although males and females cooperate in rearing chicks. Fewer than 10% of nests survive the 9-week period of laying and incubation, and of the surviving chicks, only 15% of those survive to 1 year of age.

FAQ

Does ostriches bury their heads in sand if they sense danger or take some sort of defensive gesture/stance by burying their head in order to avoid danger ?

The straight answer is "NO", they do not bury their heads in the sand, at least not to avoid danger or something like that. However they are often seen to sticking their head inside the holes where their eggs are laid. In order to provide proper heat and air flow to the eggs, the parents regularly stick their head into the holes to rotate and move the eggs which makes them look like they are burying their head in order to avoid danger.

Facts and summary

• Ostriches are large-sized flightless omnivorous birds and are the largest, tallest and heaviest birds on the planet.

• They are most commonly found in the continent of Africa in dry parts of woodlands and savannas. However, they can be also found in some Asian and Australian countries like Iraq, Iran, Southern Australia and Saudi Arabia.

• Their are 2 known  species of ostriches with one of them having 4 sub-species in it (Common Ostriches and the Somali Ostrich).

• The average lifespan of ostriches is from 40 to 45 years but can also live from 50 to 60 years, depending upon the species, region and type of environment (in the wild or in captivity).

• They have no teeth, crop , sweat glands or gallbladder. They swallow pebbles in order to use them as grinder inside their stomachs.

• Ostriches have 3 stomachs.

• They are the fastest birds on land with an average speed of 44.74 miles per hour (72 Km/h) to a maximum speed of 60 miles per hour (96.6 Km/h). They are mostly seen running at a speed of around 30 miles per hour (48.28 Km/h) without any problem and rarely run at their maximum speed, and if they do, it only lasts for a short period of time. Also, while running at peak speed they take long strides measuring from 10 to 16 feet (3.04 to 4.87 meters) in length.

• With the help of their strong and long legs, they can unleash a devastating kick towards the danger which can cause serious injury or even death.

• Ostriches fight with their feet. They can only kick forward because that's the direction in which their legs are bent.

• The red blood cells (RBC) in their blood are 3 times bigger than that of human beings. Also, the red blood cell count per unit volume in the ostrich is about 40% of that of a human.

• They have a complex heart structure.

• Male ostriches are referred as "Cocks" or "Roosters" while the females are referred as "hens".

• A group of ostriches is called as "Flock" or sometimes a "Herd".

• They do not bury their heads in the sand, at least not to avoid danger or something like that. (Reason/Answer in the FAQ above)

• Ostriches raised entirely by humans may direct their courtship and attaching behavior not at other ostriches, but towards their human keepers.

• They have the biggest eggs as compared to any bird on the Earth and can weigh over 20 times the weight of a chicken's egg. On average they are 5.9 inches (15 cm) long, 5.1 inches (13 cm) wide, and weigh 3.08 pounds (1.4 Kg) on an average and ranges from 2.42 to 4.30 pounds (~ 1.1 to 1.95 Kg).

• They can survive without water for several days or sometimes up to 2 weeks. Also, they can still survive, even after losing 25% of their body weight due to dehydration.

• In some countries in Africa, Ostrich races are held,  with special saddles and equipment.

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