Common ostriches usually weigh from 63 to 145 kilograms (139–320 lb), or as much as two adult humans. The Masai ostriches of East Africa (S. c. massaicus) averaged 115 kg (254 lb) in males and 100 kg (220 lb) in females, while the nominate subspecies, the North African ostrich (S. c. camelus), was found to average 111 kg (245 lb) in unsexed adults. Exceptional male ostriches (in the nominate subspecies) can weigh up to 156. 8 kg (346 lb). At sexual maturity (two to four years), male common ostriches can be from 2. 1 to 2. 8 m (6 ft 11 in to 9 ft 2 in) in height, while female common ostriches range from 1. 7 to 2. 0 m (5 ft 7 in to 6 ft 7 in) tall. New chicks are fawn in color, with dark brown spots. During the first year of life, chicks grow at about 25 cm (9. 8 in) per month. At one year of age, common ostriches weigh approximately 45 kilograms (99 lb). Their lifespan is up to 40–45 years.