Harpy eagles are the largest species of eagle with a body length that can range from 89 to 102 cm and a wing span of 2 m. Their talons can be up to 12.5 cm long. Females are normally larger with an average weight of 7 to 9 kg, while the males weigh an average of 5 to 8 kg. The mantle, scapulars, the top of the secondaries and primaries, secondary coverts, greater primary coverts, and the rump are slate black in color, but can vary to gray. The tail is made up of long gray feathers with horizontal black bars. The breast, belly, and flanks, are light grey with horizontal black stripes. The head, thighs and vent are light gray and the nape has a dark band across it. The crown of harpy eagles consists of long black feathers which raise when threatened, though some theorize they also raise them to direct sound to their ears. Their bills are black and their feet are yellow with black talons.
Range mass: 5 to 9 kg.
Average length: 89 to 109 cm.
Average wingspan: 2 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; female larger