28. Otidiformes (Bustards)

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 20 kg (44 lb), weigh around 13.5 kg (30 lb) on average and are capable of attaining a total length of 150 cm (59 in). The smallest species is the Little Brown Bustard (Eupodotis humilis), which is around 40 cm (16 in) long and weighs around 600 g (1.3 lb) on average.

Bustards are omnivorous, feeding principally on seeds and invertebrates. They make their nests on the ground, making their eggs and offspring often very vulnerable to predation. They walk steadily on strong legs and big toes, pecking for food as they go. Most prefer to run or walk over flying. They have long broad wings with "fingered" wingtips, and striking patterns in flight. Many have interesting mating displays, such as inflating throat sacs or elevating elaborate feathered crests. The female lays three to five dark, speckled eggs in a scrape in the ground, and incubates them alone. Bustards are gregarious outside the breeding season, but are very wary and difficult to approach in the open habitats they prefer.