Great bustard is one of the world’s largest flying birds:

• adult males stand about 105cm tall and weigh up to 18kg
• females are smaller - about 75cm tall and about 4.5kg

The bird has a stout body, long legs and neck and an upright stance. They are best known as ground birds, walking with a deliberate gait, but with a wingspan of up to 2.5m in males, they are also strong fliers. However, while capable of powerful sustained flight, they are poor gliders.Non-breeding males and females have:

• gold and black barred upperparts
• white underparts
• pale grey head, neck and breast

Breeding males differ, with long whitish chin whiskers, russet breast and lower neck. Great bustard is the only species in the genus Otis, but key features shared with other bustards are:

• no hind toe
• no preen gland
• distinctive pinkish coloured down feathers

Otis tarda was formally named by Linnaeus in 1758. However, the species was already well known to naturalists, mentioned in books back to Pliny the Elder (23–79AD), who called it avis tarda. Otis is an early Greek name for bustard, while tarda seems to come from a lost Spanish word related to ‘tread’. However, in Latin, tarda can also suggest slow and deliberate.