Bustards are a family of large terrestrial birds native to the Old World, the only one in the order of bustards. Includes 26 species and 11 genera.
Traditionally, bustards were classified as a crane-like order, and later, on the basis of molecular data, they were isolated into an independent order. Their closest relatives turned out to be cuckoo, the time of separation is estimated at about 50-60 million years ago, and more distant - turacs, these three groups form the clade Otidimorphae.
It is believed that the bustard originated in Africa on this continent, they gave significant adaptive radiation in the first half of the Tertiary period. The oldest reliably identified fossil remains of bustards belong to the Pliocene of Eurasia and North Africa, there are also dubious finds of the Miocene age.
All but one species inhabit the steppes, savannas and semi-deserts of Africa, Asia and southern Europe, and one species, the Australian bustard Ardeotis australis, is found in Australia and New Guinea. 16 species of bustard live exclusively in the tropical zone of Africa, 2 more times appear in its northern part.
Most prefer open spaces with good visibility over a considerable distance.Some African species, such as the lesser bustards Eupodotis, the crested bustards Lophotis, and the black-bellied bustards Lissotis, are tolerant of various arboreal vegetation such as acacia groves or thorny shrubs, while the small Indian bustards Sypheotides and Houbar floricans are usually found in tall areas.
The size and weight of birds varies significantly from 40 to 120 cm and from 0.45 to 19 kilograms, respectively, an inaccessible link, the largest representative of the family is considered the African great bustard Ardeotis kori, reaching a height of 110 cm and weighing up to 19 kg, which makes it one of the most massive flying birds on Earth.
The physique is strong. The head is relatively large, slightly flattened in the upper part. Male bustards Otis, great bustards Ardeotis, African bustards Neotis, black-bellied bustards Lissotis, beauty bustards Chlamydotis and floricans Houbaropsis have a feathery crest on their heads, which is especially noticeable during mating games. The beak is short and straight. The neck is long, slightly thickened. The wings are large and strong; when danger appears, the birds most often try to fly away. The legs are long, with wide and relatively short toes, on which there are rigid corpus callosities in the lower part, the hind toe is absent, which indicates their terrestrial lifestyle. Bustard males are larger than females, which is most noticeable in large species - the difference in their size reaches up to 1/3 of the length of the other sex, in smaller species the difference is less noticeable.
The plumage is mainly of protective shades: in the upper part it is brown or finely cross-striped, which well merges the bird pressed to the ground with the environment.In the lower part, the plumage is different: in species that inhabit open spaces, it is often white, and sometimes black in dense vegetation. Many species have black-and-white spots on their wings, which are invisible on the ground and are clearly visible during flight. Males, as a rule, are more brightly colored than females, at least during the breeding season, with the exception of the genus Eupodotis, where the plumage of both sexes looks the same.
Bustards are exclusively terrestrial, never using trees or shrubs. Several species, such as the bustard Otis tarda or the little bustard tetrax, gather in schools, the latter living in groups of several thousand individuals. Desert-adapted species such as the beauty bustard Chlamydotis live more secluded. Some species gather in groups only during the mating season. They can often be seen among herds of grazing animals, where they hunt disturbed insects and are more protected from attacks by predators.
Only a few populations are exclusively sedentary, while the majority are nomadic or migratory birds. Species that breed in Asia migrate long distances in winter.
Bustards are omnivores and have a very wide dietary range. However, in most species, plant food still predominates. They consume young shoots, flowers and leaves of herbaceous plants, dig up soft roots, feed on fruits and seeds. In addition, they feed on various insects: beetles, grasshoppers and other arthropods.Sometimes they eat small vertebrates: reptiles, rodents, etc., not disdaining carrion. Birds can do without water for a long time, but if it is available they drink it well.
The breeding season usually coincides with the heavy rainy season when food is abundant. When courtship, males of many species arrange magnificent demonstrations, in which they are capable of ruffling their necks, emitting an impressive drumming, as well as inflating it like a balloon. Small species, especially those living among tall grass, jump high in the air or make small flights so that it is noticeable from a distance.
As a rule, there is no long-term relationship between the female and the male, and after fertilization, the female incubates the eggs and hatches the chicks alone. The nest is arranged on the ground, in a small depression covered with grassy vegetation. The female lays 1 - 6, most often 2 - 4 eggs for several days. The incubation period is different for different species, but generally lasts in a small interval of 20 - 25 days. Chicks are of the brood type and are able to leave the nest within a few hours after birth.