- Order: Accipitriformes
- Family: Accipitridae
Crested Eagle has a broad diet of various arboreal and terrestrial prey. In one nest near Manaus, Brazil, Bierregaard (1984) noted the following prey items over the course of several months: six snakes, three of which were emerald tree boas (Corallus caninus), one unidentified frog, and eight small mammals, two of which were kinkajous (Potus flavus), the others were likely myomorpha or hysticomorpha rodents or marsupials. Also noted was the attempted take of a Gray-winged Trumpeter (Psophia crepitans). In Brazil, Crested Eagles have been observed sitting in ambush under fruiting trees and waiting for guans and trumpeters to come to feed (Sick 1993). Crested Eagles have also been seen attacking Guianan Cock-of-the-rock (Rupicola rupicola) (Bierregaard 1994). Other regular prey items include monkeys, other arboreal mammals (including opossums and squirrels), iguanas, and birds (Brown and Amadon 1968). Oversluijs Vasquez and Heymann (2001) report two successful attacks of Crested Eagles on juvenile tamarin monkeys (Saguinus mystax and Saguinus fuscicollis) in Peru. Similarly, Crested Eagles have been known to prey on juvenile spider monkeys (Ateles paniscus) in French Guiana (Julliot 1994).
Little is known about the behaviors of Crested Eagle other than nest observations and limited foraging observations.
Foraging behavior has rarely been observed, but prey is seemingly taken while in flight (Julliot 1994). In contrast to Harpy Eagle (Harpia harpyja), Crested Eagle regularly soars, either in pairs or solitary; this is generally assumed to be a foraging behavior (Wetmore 1965, Bierregaard 1994). In two specific instances, Crested Eagle behavior in taking juvenile tamarins has been reported: 1) a tamarin was taken while in flight after the eagle was seen soaring overhead (attack in exposed canopy at height of twenty meters). 2) The tamarin was taken in flight, but the eagle was seen perched about ten meters from the feeding tree before the attack (attack in sub-canopy at height of 13 meters) (Vasquez and Heymann 2001). In other observations, Crested Eagles have often been seen perched on tall roosts for long periods, possibly watching for prey (Bierregaard 1994). Most attacks on prey are in forest interior.
There is little data on territoriality for Crested Eagle. Pairs may have a range of over 100 km2, but there is no evidence that pairs defend these ranges (Galetti et al. 1997). Threat displays by juveniles and brooding females towards passing vultures may or may not indicate territoriality (Whitacre et al. 2002). Thiollay (1989) estimated a density of 4 individuals/100 km2 in French Guiana. Galletti et al. (1997) reports Crested Eagles from multiple locales that are characterized by a minimum area of 320 km2 of continuous forest. Galletti et al. (1997) also suggest that each pair of Crested Eagles may have a home range of more than 100 km2.
Little is known about courtship. Bierregaard (1984) witnessed that copulation is brief (less than ten seconds) and seems to occur in the nest. After copulation, the male hopped from perch to perch in the nest tree and gave a single high pitched whistle, but no other courtship was displayed.
Social and interspecific behavior
Solitary, except when breeding.
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.
Populations and Demography
Very little demographic data is available for this species. Females may be able to produce eggs as early as two years of age (Kiff et al. 1989). One female in captivity lived until the age of eleven years, but her cause of death is not reported (Kiff et al. 1989).
Smith, Jedediah W. 2012. Crested Eagle (Morphnus guianensis), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=129076