The great bustard (Otis tarda) is a bird in the bustard family, and the only living member of the genus Otis. It breeds in open grasslands and farmland from northern Morocco, South and Central Europe to temperate Central and East Asia. European populations are mainly resident, but Asian populations migrate farther south in winter. Endangered as of 2023, it had been listed as a Vulnerable species on the IUCN Red List since 1996.
Portugal and Spain now have about 60% of the world's great bustard population. It was driven to extinction in Great Britain, when the last bird was shot in 1832. Since 1998 The Great Bustard Group have helped reintroduce it into England on Salisbury Plain, a British Army training area. Here, the lack of public access and disturbance allows them the seclusion they desire as a large, ground-nesting bird.
The adult male great bustard is amongst the heaviest living flying animals. A male is typically 90–105 cm (2 ft 11 in – 3 ft 5 in) tall, with a length of around 115 cm (3 ft 9 in) and has a 2.1–2.7 m (6 ft 11 in – 8 ft 10 in) wingspan. The male can range in weight from 5.8 to 18 kg (13 to 40 lb). The heaviest verified specimen, collected in Manchuria, was about 21 kg (46 lb), a world record for heaviest flying bird. In a study in Spain, one male weighed as much as 19 kg (42 lb). Larger specimens have been reported but remain unverified. Average male weights as reported have been fairly variable: in Russia, males weighed a median of 9.2 kg (20 lb); in Spain, males weighed a mean of 11.62 kg (25.6 lb) during breeding season and 9.65 kg (21.3 lb) during non-breeding; in Germany, males weighed a mean of 11.97 kg (26.4 lb); and the Guinness World Records has indicated that male bustards in Great Britain weighed an average of 13.5 kg (30 lb). Average weight of males is almost an exact match to that of male Kori bustards. Among all flying animals and land birds, male Andean condors (Vultur gryphus) may match or exceed the mean body masses of these male bustards but not their maximum weights. Furthermore, male swans of the two largest species (trumpeter and mute) may attain a similar average mass depending on season and region. Among both bustards and all living birds, the upper reported mass of this species is rivaled by that of the kori bustard (Ardeotis kori), which, because of its relatively longer tarsi and tail, is both longer and taller on average and is less sexually dimorphic. In terms of weight ranges reported, the great Indian bustard (Ardeotis nigriceps) also only lags slightly behind these species.
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