Common ostrich
Common ostriches usually weigh from , or as much as two adult humans. The Masai ostriches of East Africa ("S. c. massaicus") averaged in males and in females, while the nominate subspecies, the North African ostrich ("S. c. camelus"), was found to average in unsexed adults. Exceptional male ostriches (in the nominate subspecies) can weigh up to . At sexual maturity (two to four years), male common ostriches can be from in height, while female common ostriches range from tall. New chicks are fawn in colour, with dark brown spots. During the first year of life, chicks grow at about per month. At one year of age, common ostriches weigh approximately . Their lifespan is up to 40–45 years.
Bustard
Bustards are all fairly large with the two largest species, the kori bustard ("Ardeotis kori") and the great bustard ("Otis tarda"), being frequently cited as the world's heaviest flying birds. In both the largest species, large males exceed a weight of , weigh around on average and can attain a total length of . The smallest species is the little brown bustard ("Eupodotis humilis"), which is around long and weighs around on average. In most bustards, males are substantially larger than females, often about 30% longer and sometimes more than twice the weight. They are among the most sexually dimorphic groups of birds. In only the floricans is the sexual dimorphism reverse, with the adult female being slightly larger and heavier than the male.