Identification

Huge, heavily built and robust but stately in appearance. Adult males with bulging neck, heavy chest and characteristically cocked tail adding to stocky appearance. Shape is similar to goose, but much bigger with considerably longer legs and a straighter neck. Gait slow and deliberate but capable of surprisingly fast dashes. Feeding action is a swift pick-up of food from the ground and fast ‘snatching’ of vegetation, often done with apparent petty scrutiny. Very wary nature, will often withdraw into tall vegetation but never into bushes or trees. Unable to perch, so only ever seen on the ground. Flight between 30-100 m above ground, action noticeably regular and uninterrupted, never glides, beats slow and majestic, but progress rapid. Wings long and deeply ‘fingered’ appearing mostly white. Silent, unless flushed or threatened at very close range then nasal bark sometimes heard. 

Plumage

Head and neck pale blue-grey, body and tail rufous brown with black bars, underparts white. Wings mostly white with dark secondaries and primary tips and brown forewing.

Males in breeding plumage grow large white moustachial whiskers (20 cm) and become more vividly coloured on their back and tail, also developing a band of russet coloured feathers on their lower neck and breast, amount dependent on age.

Size

Marked difference in size between male and females, termed sexual size dimorphism. Great Bustards actually exhibit the largest sexual size dimorphism of any bird species and even most other vertebrates! Female Great Bustards can be as much as 50 % smaller than males.

Males: Standing height 90-105 cm. Wingspan 210-250 cm. Weight 8-16 kg but reports of over 20 kg make them the world’s heaviest flying bird!
Females: Standing height 75-85 cm. Wingspan 170-190 cm. Weight 3.5-5 kg.

Voice

Adults 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 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, first heard from the egg prior to hatching which continues until chicks are several months old.