Ornate Hawk-eagle

This is a medium-to-large sized species of raptor but a fairly small eagle. In the ornate hawk-eagle, the sexes are similar in appearance and overlap in size but like most birds of prey do show reverse sexual dimorphism, in which females outsize males to the contrary of most non-raptorial birds. The biggest female ornate hawk-eagles are 13% larger than biggest males, with an average of about 8% greater in nominate race. In Central America, in extreme cases, the largest females are as much as 50% heavier than the smallest males. The species is slightly smaller than the largest members of widespread raptor genera such as the largest Buteo and Falco species but is usually larger than other forest raptors in its range apart from vultures and other eagle species. The total length of full grown ornate hawk-eagle is 56.0 to 68.5 cm (22.0 to 27.0 in). Average total length is estimated at 60 cm (24 in) for males and 63 cm (25 in) for females. The wingspan may range from 117 to 142 cm (3 ft 10 in to 4 ft 8 in). Body mass can vary in males from 835 to 1,215 g (1.841 to 2.679 lb) and in females from 950 to 1,760 g (2.09 to 3.88 lb). The average weight of five adult males was 1,009 g (2.224 lb) while another five males averaged 1,035 g (2.282 lb). The average weight of four adult females was 1,421 g (3.133 lb) while a sample of 11 averaged 1,452 g (3.201 lb). Among standard measurements, wing chord measures from 312 to 360 mm (12.3 to 14.2 in) in males and 320 to 405 mm (12.6 to 15.9 in) against S. o. vicarius in which wing chord is known to measure 337.8 to 349.3 mm (13.30 to 13.75 in) in males and 353.3 to 388 mm (13.91 to 15.28 in). In tail length, males vary from 244 to 268 mm (9.6 to 10.6 in) and females from 266 to 290 mm (10.5 to 11.4 in). The culmen from cere measures 25.5 to 29 mm (1.00 to 1.14 in) in males and 27 to 31.5 mm (1.06 to 1.24 in). In tarsus length, males may measure 87 to 92 mm (3.4 to 3.6 in) and females may measure 89.5 to 100 mm (3.52 to 3.94 in). Average wing chord lengths from Guatemala (S. o. vicarius), showed 7 males to average 339.8 mm (13.38 in) and 8 females to average 377.8 mm (14.87 in). Meanwhile, in the same sample, mean tail length was 255.6 mm (10.06 in) in males and 281.6 mm (11.09 in) in females and mean tarsus length was 89 mm (3.5 in) and 94.1 mm (3.70 in) in the sexes, respectively. The largest rear talon (or hallux claw) present on all accipitrids (usually the main killing tool in these predator's arsenal) is particularly enlarged on the ornate hawk-eagle relative to its size, averaging about 36.7 mm (1.44 in) in males and 39.1 mm (1.54 in) in females from Guatemala, with an average foot span for both sexes measuring around 13.5 cm (5.3 in). Ornate hawk-eagles largely perch within the tree canopy, but will sometimes be out on exposed branches especially earlier in the morning. Usually soaring activity peaks in the late morning. Brown & Amadon (1986) described the species are “rather stolid and buteonine, despite the long tail and crest”. Adults are largely distinguishable by their rufous cowls and bold barring below. Furthermore, all ornate hawk-eagles bear a long erectile crest, which may variously be laid flat against the head, protrude straight up like a spike or sometimes hang at a slight curve. Adults when perched have an obvious black crown, crest and malar stripes (continuing to sides as isolated streaks) sets off by the rufous color on their cheeks, ear-coverts and sides of the neck and chest (sometimes completely covering their upper chests), the rufous shading into a somewhat browner rufous nape. On the upperside, they are barred blackish to dark brown with usually apparent white tips on the mantle and lesser wing coverts. Meanwhile, on the underside, they have a whitish base color which, other than the often plain throat, is boldly overlaid with black barring. This barring extends down to the abdomen and legs, while the crissum is spotted black. Like many forest raptors, the species has relatively short wings and a longish tail. When perched, their wing tips slightly exceed their tail base. The tail is blackish with a creamy whitish tip and three broad pale bands, which are greyish above and whitish below, the basal bar often being obscured. According to Brown & Amadon “the perched bird seemingly has legs set very far forward, almost under the chest, thus giving the impression of posed readiness. The position of the black crest hints at the bird's temper at the moment”. Juvenile differ conspicuously in many respects, generally lacking most of the pigment visible in adults. Juveniles lack the adults’ rufous collar, malar stripes and underside barring. Instead, the juvenile's whole head and underparts are white excepting thin black streaks on the crown and the tip of their crest. Some juvenile ornate hawk-eagles do, however, show variable, light dark brown barring and spotting on the flanks and thighs, at even may manifest a vestigial moustache on the face. The juvenile's back and wings are dark brown with white-tipped blackish shoulders. The tail is somewhat similar to the adult's but has a broader white tip and at least 4-5 thinner bands, which like those of the adult are greyish above and whitish below. By their 2nd year, the young hawk-eagles enter an intermediate or subadult plumage that quickly starts to resemble that of the adults but is rather more faded in appearance. The subadult's face is a sandy to pale rufous color with an indistinct malar stripe, while the flanks, belly and legs increasingly start to manifest barring and spotting. The subadult's back is still largely dark brown but tends to appear increasingly blackish. Adults have orangish-yellow eyes, with a dull greenish to grey color on the cere and bare lores, while the feet are rich cream to pale yellow. Juveniles have white to whitish-yellow eyes, a yellow to bluish-grey cere and brighter yellow to orange feet. Apparently, the legs of juveniles are often less thickly feathered than those of adults. In flight it may appear intermediate in size, being large relative to most forest raptors but rather small and slender-bodied for an eagle. The flying ornate hawk-eagle is prominent headed with short, broad rounded wings that show an emphasis on the bulging secondaries and pinch in at the bases of the trailing edges. Flight of the species is deep and powerful with the wings held flattish and pressed slightly forward, while the tail may be closed to slightly spread. From above, adult has a rufous cowl, a blackish mantle and a slightly brownish black back and wings with white-tipped shoulders and tail coverts. Below the underwing is paler looking relative to body with flecking or speckling only on the hand and thinly barred flight feathers. In flight, the juvenile ornate hawk-eagle is mainly dark brown above with whitish scaled blackish-brown shoulders. Below, the juvenile's wings have scattered spots on the axillaries and great wing-coverts, blackish tips to the white based outer primaries and thin barring on the other flight feathers, at times matching the patterning of the tail. By the 2nd year, there is an only moderate increase to the flecks and spots on the wing linings, as the flight feathers and tail are the last to molt away from the juvenile-like look to those like adults.