An adult kagu is about the size of a domestic chicken, with a head-and-body length of about 22 inches (55 centimeters), and a weight of 1.5 to 2.5 pounds (24 to 40 ounces). A kagu resembles a small crane with a coat of very light gray feathers, a short tail, and reddish-orange beak, eyes, legs, and feet. A crest of feathers crowns the kagu's head. When not raised for display, the crest lays down towards the back of the head.
The beak is long and slender. The edges of the nostrils are raised into ringlike flanges, making the nostrils look like short tubes. The flanges keep soil from getting into the nostrils as the bird forages in leaf litter and soil for food. The scientific name of the bird, Rhynochetos jubatus, from the Latin, translates as "tube-nosed, head-crested."
The wings are light gray with black, dark, lighter gray, and brownish spots arranged in rows or bars along the outer sides of the open wings. The dark spots are covered when the wings are closed. Although the wings are large and look flightworthy, kagus cannot fly, since they have lost most of the mass of their once-powerful flight muscles. The open wingspan can reach 32 inches (80 centimeters).
Although most bird species that spend time on forest floors are camouflaged (KAM-uh-flajd), the adult kagu doesn't follow that rule, being light-colored and very obvious in a dark forest. It may be that kagus never needed camouflage before people brought dogs, cats, and other predators, animals that hunt them for food, to Grand Terre. Or, the light coats may have evolved for a territorial role, enabling kagus to easily spot other kagus, during mating times or for defending territories. Kagus are always ready to chase off other kagus that intrude on individual territories. Kagu chicks are brown and light brown colored, which does help them to blend into the colors of the forest floor.