Male great bustards become sexually mature at four to five years of age, while females are known to have bred at just one year of age (5). Males compete in what is known as a lekking system, gathering together at small display grounds (known as a 'lek') from where they attempt to impress females (6). The nests, which are shallow pits on dry, soft slopes and plains, are usually situated close to leks. After the female has chosen a male and mated with him, she lays one to three eggs and incubates them for 21 to 28 days (5) (6). The male does not incubate the eggs or contribute to caring for the chicks. The chicks can stand soon after hatching and will forage alone after ten days. After 30 to 35 days, the fledglings will be able to fly (6). Some great bustard populations are migratory (5), and gather in large numbers at pre-migratory sites in order to move collectively to winter grounds (6). Both winter and summer grounds differ between populations.