This species often overlaps in range with the less scarce Harpy eagle, which is likely its close relative and is somewhat similar to appearance. There is evidence of an interesting interspecific relationship between and adult Crested eagle feeding a juvenile Harpy eagle in Panama, while the adult Harpy eagles were away. During these interactions, the Crested eagle brought new nesting material to the nest and in occasions brought food to the juvenile Harpy eagle. The Crested eagle is roughly half that species' bulk and is clearly more slender. Generally, Crested eagles are silent but do make a call occasionally that consists of a pair of high whistles, with the second whistle being higher pitched than the first.