Crane

Cranes are very large birds, often considered the world's tallest flying birds. They range in size from the demoiselle crane, which measures 90 cm in length, to the sarus crane, which can be up to 176 cm, although the heaviest is the red-crowned crane, which can weigh 12 kg prior to migrating. They are long-legged and long-necked birds with streamlined bodies and large, rounded wings. The males and females do not vary in external appearance, but males tend to be slightly larger than females.

The plumage of cranes varies by habitat. Species inhabiting vast, open wetlands tend to have more white in their plumage than do species that inhabit smaller wetlands or forested habitats, which tend to be more grey. These white species are also generally larger. The smaller size and colour of the forest species is thought to help them maintain a less conspicuous profile while nesting; two of these species (the common and sandhill cranes) also daub their feathers with mud which some observers suspect helps them to hide while nesting.

The Crane

The long coiled trachea that produces the trumpeting calls of cranes (sarus crane, Antigone antigone). Most species of cranes have some areas of bare skin on their faces; the only two exceptions are the blue and demoiselle cranes. This skin is used in communication with other cranes, and can be expanded by contracting and relaxing muscles, and change the intensity of colour. Feathers on the head can be moved and erected in the blue, wattled, and demoiselle cranes for signaling, as well.

Also important to communication is the position and length of the trachea. In the two crowned cranes, the trachea is shorter and only slightly impressed upon the bone of the sternum, whereas the trachea of the other species is longer and penetrates the sternum. In some species, the entire sternum is fused to the bony plates of the trachea, and this helps amplify the crane's calls, allowing them to carry for several kilometres.