Classification The monophyletic order Gruiforme comprises Rallidae (Rails, Gallinules, Crakes and Coots), Gruidae (Cranes), Aramidae (Limpkin), Psophiidae (Trumpeters), in addition to Heliornithidae (Finfoots) and Sarothruridae (Flufftails) not shown here. These "core gruiformes" exclude orders and families now known to have a distinct ancestor, among which are Seriemas (Cariamiformes), Mesites (Mesitornithiformes), Sunbittern and Kagu (Eurypygiformes), and Bustards (Otidiformes).
Rallidae are medium-size running, wading and swimming marsh inhabitants; they are one of the world most widespread bird families. They look like chicken, as shown by such names as "swamp hens", "moor hens". Coots have a frontal shield and are good swimmers and divers, have lobate-webbed toes similar to those of grebes. Gallinules also have a frontal shield as well as greatly elongated webbless toes to support them in marsh vegetation. Rallidae are often weak fliers; flight has been lost in at least one fourth of all rails, living or extinct.
Gruidae (Cranes) fly with neck straight out and superficially resemble storks. They are very gregarious and fly in large flocks, forming a strong V or an an extended echelon, often at high altitudes, up to 2 miles.They are known for their extraordinary dancing parties, part of their courtship, but also throughout the year as an expression of their natural liveliness.
Aramidae (Limpkins), named from their limping gait, are the link between Rallidae and Gruidae. They can swim and are primarily marsh birds but can perch in trees. Their main food is mollusks, both univalve and bivalve, which they extract with their powerfull beak.
Psophiidae (Trumpeters) are a family of three species of ground-dwelling, gregarious birds of northeastern South American forests, which emit loud trumpeting and booming calls from which their name come. They are weak-winged and would rather run than fly. They can swim. They are sociable, easily captured and domesticated.
Austin O.L., Jr, Singer A.(1961): Birds of the World, Golden Press, New York.
Feduccia A. (1996): The Origin and Evolution of Birds (Yale Univ Press, New Haven, CT). Chapter 6 discusses the evolution of flightlessness.