Contrary to popular belief, only one species of flightless bird belongs to the ostrich family - African ostrich. According to the zoological classification, emus, nandus and cassowaries are not ostriches, although they have an external resemblance to them. Let’s try to figure out what is the difference between these unusual representatives of the fauna, and also find out how much the real ostrich and its closest brothers weigh.
Giant from the expanses of hot Africa
Ostriches living on the African continent are divided into several subspecies. They are distinguished by the color of the limbs and plumage. In the eastern part of the mainland, black birds with reddish legs and necks predominate. The birds, who have chosen the southwestern and northern regions of Africa, have blue paws and a grayish-brown color of feathers.
A distinctive feature of a true ostrich is its bare neck and powerful two-toed legs, whose fly-force is so great that at moments of danger the bird is able to immediately kill a predator, for example a lion. This is not surprising, given how much the ostrich weighs - the body weight of large males can reach 160 or more kilograms with an increase of about three meters. The sizes of medium-sized individuals are slightly smaller, but also impressive: their length is 180–230 cm in height and their weight is from 120 to 150 kg.
In nature, ostriches are kept in herds of ten to fifty heads. Although these birds are deprived of the opportunity to fly, rarely can anyone compete with them in speed of running. On a flat terrain without obstacles, an ostrich is capable of speeds up to 90 km / h, on average - 50 km / h with a step length of three to four meters.
Features of reproduction of African ostrich
Females have a more modest color and relatively small sizes (from 100 to 120 kg), which roughly corresponds to how much the ostrich weighs per year. During the mating season, the herds are divided into small "harems" of 3-5 females under the leadership of the male.
A common clutch of 15-20 (less often 30) eggs during daylight hours is selected by a selected pair of birds in turn. At night, only the head of the "harem" is engaged in hatching. Chicks are born in 35-45 days, breaking through a thick shell with their heads. Because of this, they form bruises on the back of the head, absorbable as the babies grow older. The mass of the newly hatched ostrich is 0.9–1.2 kg, and its length is about 25 cm. In the first week of life, the chicks do not eat or drink anything, and then begin to grow by 1-2 centimeters daily and gain weight quite quickly .
Considering how much an adult ostrich weighs, it can be assumed that from the moment of birth, the chick gains 10-12 kilograms per month, since at the age of 1 year, his body weight already exceeds a centner. But puberty in these birds occurs only with two, and sometimes with four years. Interestingly, the lifespan of these giants can reach 70-75 years, half of which they do not lose the ability to reproduce offspring.
South American Rhea
The flightless bird native to South America looks very much like an African relative. However, this species belongs to the order of nanduiformes, its neck is covered with feathers, and on each paw there are three fingers. The growth of the rhea compared to the real ostrich is small - only about one and a half meters. The raucous voice of a feathered runner resembles either a cat hiss or a formidable lion's roar, in which the sound of “nan-do” is heard, which is why the bird got its name.
Zoologists have not been able to determine exactly how much the ostrich rhea weighs . According to some reports, the maximum mass of his body is 40 kg, according to others - no more than 30. The inhabitants of the South American savannah move quite quickly - up to 60 km / h. They also know how to swim well and defend themselves from enemies with the help of legs and sharp claws on the wings. There is an opinion that the Nandus lived on our planet already during the Paleocene, that is 66 million years ago and, thus, are the oldest species of all the birds existing today.
Australian emu
The handsome emu is a native of the Green Continent. This bird, like its closest relatives, is not able to fly, but runs great, developing a speed of up to 50 km / h. Unlike the African ostrich, the emu has thinner, but rather strong legs. Each paw is equipped with three clawed fingers and soft pads on the feet.
The mismatch in the structure of the limbs has become one of the main reasons that emu and African ostrich are classified as different types of birds. Aussie is only slightly smaller than a true ostrich. Mature individuals reach a size of 1.7-1.9 meters.
How much an ostrich emu weighs depends a lot on his living conditions. In the wild, where birds are forced to travel long distances in search of food and escape from enemies, their weight rarely exceeds 50-55 kg. When breeding on farms, due to intensive feeding and care, individual specimens reach sizes of about 70-75 kilograms.
Emu propagation in nature and captivity
Male and female individuals are practically indistinguishable by color, height, and body structure. They can only be recognized by the timbre of sounds made during the mating season. As with the African flightless birds, the male takes care of the future offspring without leaving the nest for 55-60 days, eating only dew drops.
Knowing how much an adult ostrich emu weighs, it is easy to guess that a selfless dad in two months is greatly depleted. But this does not prevent him from subsequently taking care of the chicks with equal care, taking them for a walk, and protecting them from attack by predators.
In artificial conditions, for the same period, eggs are laid in an incubator. After the due period of young green eggs amicably emerges from dark green eggs. The mass of each chick is usually 300-500 grams. The baby's body has a beautiful striped color, and black and white spots are clearly visible on the head.
Who are cassowaries
Until recently, emu was classified as ostrich-shaped. In the eighties of the last century, scientists, having studied the structural features of the African ostrich and other birds similar to it, came to the conclusion that emu is an independent species from the order of cassowary. The second representative of the family is cassowary.
On the head of these large birds living in New Guinea and northeastern regions of Australia, there is a kind of growth, for which they are called "helmet-bearing". In growth, they are slightly inferior to emu, but surpass them in body weight. The height of the cassowary is 1.5-1.8 meters, and the weight can reach 80 kilograms.
These birds run fast, swim perfectly and are able to jump up to one and a half meters. A sharp long claw on the middle finger of the feathered three-toed paw allows him to deliver fatal blows to enemies. It is believed that, unlike the friendly emu, cassowaries have a non-existent character and prefer to stay away not only from other animals, but also from their blood relatives.