The cranes are the largest of the Gruiformes and among them is the tallest flying bird on the planet—the sarus crane which stands over 5 feet tall. Cranes have long legs and long necks and an impressive wingspan measuring between 6 and 7 feet. Most cranes are predominantly pale grey or white in color with accents of red and black feathers on their face. The black-crowned crane is the most ornate of all cranes with a tuft of golden bristle-plumes atop its head. There are 15 species of cranes worldwide.
The rails, another subgroup of the Gruiformes, are smaller than cranes. The rails include crakes, coots, and gallinules. Although some species of rails undergo seasonal migrations, most rails are not powerful in flight and show a preference to running along the ground instead of taking to the air. Species that have colonized islands where there are few predators have in many cases lost their ability to fly over the course of their evolution. Their flightlessness has made them vulnerable to invasive predators such as snakes, rats and feral cats.