Classification As originally defined, the Gruiforme order included the Otitidae family. This definition rendered "Gruiformes" non monophylic since phylogenomic analyses showed that Cuculiformes (Cuckoos) would then be included in it. Monophyly was restored by recognizing Otidiformes, Cuculiformes and the newly defined Gruiformes as separate orders.

All  bustards are shy, wary, keen-sighted birds of the open, treeless country. They normally walk with a dignified, elegant gait. They fly reluctantly, but powerfully and usually depend on running to escape their enemies.

Some of the paleoartic species perform extensive migrations, flying in typical crane fashion.  While the little Bustard, shown in Catalonia (Spain) and several African species are chicken sized, most of them are considerably larger. The Kori Bustard, photographed in Tanzania and Namibia, is the heaviest flying bird (male up to 19 kg, 42 pounds), together with the Great Bustard of Eurasia (the largest male on record weighted 16 kg, 37 pounds). The latter is known for its splendid display, in which he seems "to turn himself inside out".

Bustards feed on ants, crickets, locusts and other insects but plants are also a significant part of their diet. Females lay two, three and occasionally four eggs on the ground, making little or no nest, once a year. Incubation lasts 22 days, but at day 21, chicks make a hole in their shells and they begin to breathe through this hole.

Hackett SJ et al (2008): Phylogenomic Study of Birds

http://en.wikipehttp://en.wikipedia.org/wiki/Bustard

Austin Jr, O.L, (1961), Birds of the World, Golden Press, New York