The Great Bustard, Otis tarda, is in the bustard family, the only member of the genus Otis. It breeds in southern and central Europe, where it is the largest species of bird, and across temperate Asia. European populations are mainly resident, but Asian birds move further south in winter.

This species is declining due to habitat loss throughout its range. It used to breed more widely and was extinct in the British Isles between 1832 and an artificial reintroduction to Salisbury Plain in 2004. It forms part of the design of the Wiltshire Coat of Arms. It was also found in the B?r?gan region of Romania, but went extinct in 1967. Sizeable populations exist in Hungary, Portugal, Slovakia, Russia and Spain.

The male of this huge bird is possibly the heaviest extant bird capable of flight, alongside the similarly-sized Kori Bustard. An adult male typically is 90-110 cm (3-3.7 ft) long with a 2.1-2.5 m (6.9-8.2 ft) wingspan and usually weigh from 10 to 16 kg (22-35 lb). The heaviest known bird was about 21 kg (46 lb), although larger specimens have been reported and not verified. An adult male is brown above and white below, with a long grey neck and head. The breast and lower neck sides are chestnut. In the breeding season, the male has long white neck bristles. In flight, the long wings show large areas of white.

The female is 30% smaller, typically 80 cm in length and 1.8 m across the wings, and half the weight, averaging 3.5-5 kg (6-11 lb). The breast and neck are buff. Both sexes are usually silent. Immature birds resemble the female.

Before mating, the males moult into their breeding plumage around January. Like other bustards, the male Great Bustard has a flamboyant display showing much white, mainly from the undertail, and withdrawing the head. The Great Bustard breeds in March, and a single male may mate with up to 5 females. All breeding Great Bustards also moult again from June to September.

Great Bustard at the Beijing Zoo.

2-3 olive or tan coloured, glossy eggs are laid in a small ground scrape. The female incubates the eggs alone for around 4 weeks. The chicks almost immediately leave the nest after they hatch, although they do not move very far from their mother until they are at least 1 year old. Males usually start to mate from about 5 years old. Great Bustards typically live for around 10 years, but some have been known to live up to 15 years or more.

This bird's habitat is open grassland, although it can be found on undisturbed cultivation. It has a stately slow walk, and tends to run when disturbed rather than fly. It is gregarious, especially in winter. This species is omnivorous, taking seeds, insects and other small creatures, including frogs and beetles.

Populations

Populations vary from region to region with 1,400 Great Bustard individuals residing in Portugal, another large population of around 6,000-7,000 birds resident near Saratov in Russia and 23,000 individuals in Spain. Sizeable populations still exist in Hungary, where the Eastern European steppe zone ends, near Dévaványa town and also in the Hortobágy, Nagykunság and Nagy-Sárrét regions. There were 1,350 birds in February 2006, down from a population of 10,000-12,000 before the Second World War. The Hungarian authorities seek to preserve the long-term future of the population by active protection measures: the area affected by the special ecological treatment grew to 15 square kilometres by the summer of 2006.

Two very rare albino Great Bustards from the same nest were killed by electricity cables in Hungary in 2000 and 2003. The bustards, despite their large size, are able to fly at a high velocity (60 kilometre/hour) and are often mutilated or killed by the cables which are placed in Hungary just at their flying heights. The electricity companies affected will bury only part of the dangerous cables, therefore the authorities are experimenting with fixing fluorescent "Firefly" devices on the most dangerous cables to provide the birds with warning lights. (The funds available are not sufficient for a full treatment of the problem.)

The Great Bustard, túzok in Hungarian, is a national bird of Hungary and a subject of several proverbs.