It is about 81 centimetres (32 in) long, of which more than half is the pointed, graduated tail typical of all macaws, though the scarlet macaw has a larger percentage of tail than the other large macaws. The average weight is about 1 kilogram (2.2 lb). The plumage is mostly scarlet, but the rump and tail-covert feathers are light blue, the greater upper wingcoverts are yellow, the upper sides of the flight feathers of the wings are dark blue as are the ends of the tail feathers, and the undersides of the wing and tail flight feathers are dark red with metallic gold iridescence. Some individuals may have green in the wings.
A typical sighting is of a single bird or a pair flying above the forest canopy, though in some areas flocks can be seen. They may gather at clay licks. Scarlet macaws communicate primarily through raucous honks; however, vocal communication is highly variable, and captive macaws are known to be adept mimics of human speech.
In the wild
The South American range is extensive and covers the Amazon basin; extending to Peru east of the Andes, to Bolivia. In Central American the range extends from extreme eastern and southern Mexico and Panama through Guatemala and Belize, the island of Coiba and infrequently on the mainland of Panama, and two isolated regions on the Pacific Coast of Costa Rica; the Carara National Park and Peninsula de Osa. Scarlet macaws inhabit humid lowland subtropical rain forests, open woodlands, river edges, and savannas.
Scarlet macaws eat mostly fruits, nuts and seeds, including large, hard seeds.