What are Great Bustards?
The Great Bustard (Otis tarda) is one of the heaviest flying birds alive today and can be found across Europe, as far south as Spain and as far north as the Russian steppes. The conservation status of the Great Bustard is listed as vulnerable, with populations in many countries being in decline. The species became extinct in the UK in 1832.
Most members of the bustard family are smaller than the Great Bustard - only the Kori Bustard and the Great Indian Bustard are of a similar size. Male Great Bustards grow about 30% larger than the females, reaching up to one metre tall and weighing up to 16kg. The heaviest recorded Great Bustard weighed in at 21kg.
Huge, heavily built and robust but stately in appearance, adult male bustards can be identified by their bulging neck, heavy chest and characteristically cocked tail. Shape is similar to a large goose, but the bustard is much larger with considerably longer legs and a straighter neck. The head and neck are a pale blue-grey, the body and tail rufous brown with black bars, and underparts white. The wings of the Great Bustard are mostly white with dark primary and secondary feathers.
Males in breeding plumage grow large white moustachial whiskers (20cm long) and become more vividly coloured on their back and tail. They also develop a band of russet coloured feathers on their lower neck and breast, which becomes wider and brighter as they get older.
There is a marked difference in size between males and females, termed sexual size dimorphism. Great Bustards actually exhibit the largest sexual size dimorphism of any bird species and most other mammals, birds, reptiles, amphibians, and fish! Female Great Bustards can be as much as 50% smaller than males.
Males: Standing height 90-105cm. Wingspan 210-250cm. Weight 8-16kg.
Females: Standing height 75-85cm. Wingspan 170-190cm. Weight 3.5-5kg.
Adults are usually silent but males can sometimes be heard when fighting in breeding season. They use a variety of gruff nasal barks and also a soft "umb, umb" sound, which is sometimes heard as the gular (throat) pouch is inflated and deflated during display.
The young also have a number of calls including a high plaintive whistle. This is first heard from the egg prior to hatching and it continues until chicks are several months old.
More detailed information on the Great Bustard can be found here.