Nesting behavior is perhaps the best documented aspect of Crested Eagle behavior. The discussion that follows is from observations by Bierregaard (1984, 1994), Kiff et al. (1989) and Whitacre et al. (2002).
Nest trees are usually emergent, or at least afford a clear view of the canopy. The two nest trees documented by Bierregaard (1984) and Kiff et al. (1989) were a jobillo tree (Astronium graveolens) and a tree in Lecythidaceae; nest heights were 16.4 m and 28 m respectively. The nest is constructed of bulky sticks in the crotch of trees (Bierregaard 1994). During incubation, the male is the sole provider for both adults, returning food to the incubating female. When disturbed by humans, the female does not go far from the nest (less than 20 m) and returns nearly instantly to incubate the eggs. Also, no aggressive behavior appears to be displayed towards humans. Nesting has been reported in May and April with copulation occurring in early March. A typical clutch size of two eggs is likely, although only one young has ever been reported to be reared. The eggs from two captive females (one in Los Angeles Zoo and one in the Center for Propagation of Endangered Panamanian Species in Panama) were both dull white in color and unmarked aside from nest stains. The eggs were noted to be short, sub-elliptical in shape. Egg dimensions were 64.0 x 50.7 mm; dry shell weight of 7.614 grams, fresh weight of 90.5 grams, egg shell thickness of 0.565 mm (one egg from Center for Propagation of Endangered Panamanian Species in Panama)
Hatchlings (Bierregaard 1994, Whitacre et al. 2002): Covert feathers emerge from quills around twenty-one days of age. By four weeks, primary feathers are emerging from sheaths. By day ninety-four, the primaries are hard-penned and the tail was still growing. Chicks fledge around 100-110 days of age.
Once the egg hatches, the female is nearly always in attendance and broods until she starts to deliver food to the chick (about a month after hatching). On sunny days, the female allows the chick to move around and sit in her shade. She also broods over the chick in the rain. When the male brings food, he announces his arrival with a call and remains at the nest for only a few minutes. Once the female starts foraging, she rarely returns without food or fresh sticks to be placed in the nest. The female is the only parent that feeds the young and keeps the nest clean.
The nestling can stand and move about the nest by 30 days of age, vocalizes in response to threats by 40 days (threats consist of passing birds), can stand for extended periods by 60 days, can feed itself (from prey brought to the nest by an adult) by 80 days and fledges at about 110 days. Even after the chick has fledged, it is still dependent on its parents for food. It remains in the general vicinity of the nest and returns to the nest when an adult brings food. This behavior continues up to 16 months of age. Due to this long development time, mating pairs are likely to nest and fledge young only every two or three years.