Ornate hawk-eagle

The ornate hawk-eagle is a member of the booted eagle subfamily, with the signature well-feathered tarsi present on both tropical and temperate species (and shared, presumably through convergent evolution, with a pair of buteonine hawks). The history of the American Spizaetus genus has been indicated by the diversity of hawk-eagles found in the fossil records in the United States and Mexico. At least five such species have been described, having presumably radiated from basal hawk-eagles of Asian origin across the Bering Land Bridge. Some of these are ancestors of modern Spizaetus species, with the genera having been present in North America at least since the Pliocene. Some forms were considerably more massive than any extant hawk-eagle and indeed were likely to have exceeded the size of any living booted eagle. Fossil species such as Spizaetus willetti may have grown to similar sizes as the modern harpy eagle (Harpia harpyja). Genetic markers indicate the black-and-white hawk-eagle (Spizaetus melanoleucus) and especially the black-and-chestnut eagle (Spizaetus isidori) are closely related to the ornate hawk-eagle, resulting in their respective former genera of Spizastur and Oroaetus being eliminated. The fourth neotropical hawk-eagle, the black hawk-eagle (Spizaetus tyrannus), has been found to be basal to the other extant species. The subspecies seem to differ mostly in the plumage characteristics of adults. Whereas the nominate birds are a more cinnamon-hued color on the neck with slightly paler ground color and sparser markings about the head and undersides, S. o. vicarius, tends to be darker overall, with a richer, deeper. more rufous color around the neck, denser and darker markings overall, and broader bands on the tail. == Description ==

(Panama) This is a medium to large-sized species of raptor, but small for an eagle. Average total length is estimated at for males and for females. The wingspan may range from . The average weight of five adult males was while another five males averaged . The average weight of four adult females was , while a sample of 11 averaged . 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. 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. Distant gray-bellied hawks are best told apart by their very different proportions and build both in flight and perched. The gray-bellied hawks are typical of an Accipiter, having broader and much shorter wings, relatively more elongated tail and signature flap-flap-glide flight style. Although the gray-bellied hawk is by a slight margin the largest member of that genus in South America, it is still considerably smaller than the hawk-eagle, averaging about a third smaller in length. At close range, it may noticeably differ, beyond the size discrepancy, by the hawk being crestless and bearing relatively long, featherless and yellow legs. The juvenile ornate hawk-eagle is potentially confusable with the black-and-white hawk-eagle but the latter is smaller with boxier wings, shorter crest, a bold orange cere, a strong black mask and a blacker upper-body with white leading edges. Also the black-and-white bears no spots or barring on its wings and has a plain white underbody. Juvenile hook-billed kite (Chondrohierax uncinatus) are also potentially confusable with juvenile ornates but the kite is much smaller and more dumpily built with more paddle-shaped wings, a squarer tail, with clearer bars on remiges and rectrices and bare tarsi. Another kite, the gray-headed kite (Leptodon cayanensis) can be considered similar in plumage in its adult plumage to the juvenile ornate but it is rather smaller with very different shape in all respects (especially in its small, pigeon-like head), completely different underwing pattern and unmarked body but for grey crown and nape. Despite its somewhat similar plumage and appearance to the crested eagle, the harpy eagle is far more massive than the ornate hawk-eagle (nearly five times heavier on average) and unlikely to be confused with any plumage of the smaller species. Unlike the call of the black hawk-eagle, similarly done in flying display, the ornate hawk-eagle the introductory series of notes is more hurried and the last note more drawn out. It has been noted by some authors that the ornate species' call in nearly a reverse of the pattern of the calling black hawk-eagle which calls , the first note being longest and slurred, second note highest, followed by descending short notes. == Range and habitat ==

, Mexico showing characteristic preference for dense forest with tall trees The ornate hawk-eagle has the largest distribution of the nine species of eagle endemic to the neotropics, ranging over an estimated 20.2 million square kilometers in total. Reportage of the species is known in the Mexican states of Guerrero and Nayarit but these could pertain to wandering individuals. Nesting remains unconfirmed throughout west Mexico and since most birds seen are juveniles, these could refer to post-dispersal wanderers. The species is found almost continuously through Central America in Belize, Guatemala, El Salvador, Honduras and Nicaragua into Costa Rica and Panama (including the isle of Coiba). In Brazil, it occupies nearly two-thirds of the large country south to Paraná and marginally into Santa Catarina and Rio Grande do Sul but is largely (if not entirely) absent from Mato Grosso do Sul, Minas Gerais and more or less the entirety of the northeast region. More so than black hawk-eagles, the ornate hawk-eagle tends to be found primarily only in unbroken primary forest tracts. The ornate hawk-eagle may be found at sea level to , also rarely to about . However, they've been recorded wandering to in Costa Rica. The species adapts quite well to cloud forest habitat, which are usually at higher elevations than typical rainforest habitats (i.e., in primary cloud forest of southern Mexico, the ornate hawk-eagle was one of the two most frequently recorded raptor species). In some areas, the hawk-eagles may occasional habituate partially to edges, riversides and other openings, also into gallery strips and relatively short swamp forest. In Guatemala, they are often fairly distant from openings and dwell almost entirely in primary forest, especially areas where at least one very tall tree emerged above the average canopy level and there is less forest understory to more easily execute hunting. The Guatemalan hawk-eagles preferred fairly homogenous forest in drier upland parts of the humid forest, since the hilly areas of the forest tended to have more of the aforementioned habitat characteristic. However, the hawk-eagles here did sometimes occur in scrub-swamp forests as long as it retained tall trees, however the ornate hawk-eagles who nested in scrub-swamp forest type often went to the upland areas to hunt. == Dietary habits ==

, are often favored in the diet. The ornate hawk-eagle is a powerful predator that readily varies its prey selection among two main prey groups. Largely the most significant prey for the species are medium to large sized birds. The other main prey type are a variety of small to medium-sized mammals. On occasion, reptiles may form a seldom part of the diet. The agility imparted by its relative small and broad wings and longish tail and talent for tail-chases in enclosed woods and thickets are why this and similar eagles are referred to as "hawk-eagles", in reference to similar hunting styles in the "true hawks" (i.e., the members of the Accipiter and Astur genera). In size, tail length and hunting style, the ornate hawk-eagle in particular is quite similar to the largest races of the larger Astur species (formerly Accipiter), the Eurasian goshawk (Astur gentilis). Most witnessed tail-chases by this species have involved chasing various gamebirds, with about equal accounts of successful and unsuccessful pursuits. In Guatemala, most attacks were launched when the hawk-eagle was from its quarry, with all successful attacks on prey on ground or low bushes and were from perches at high or lower in the trees. In attacking Guianan cock-of-the-rock (Rupicola rupicola) on their mating lek, 2 of 8 attempted attacks by ornate hawk-eagles were successful (and were the only successful attacks of 56 total attempts, the other 48 by different raptor species). The hawk-eagles made bold, fast dives into the middle of the leks, quickly grabbing a male cock-of-the-rock. Subsequently, one hawk-eagle consumed the bird right on the spot in one case and the other took its catch to a nearby perch. Reported instances of "power dives" into troops of monkeys and even heronries are probably similar in nature to the cock-of-the-rock attacks. In one case, an ornate hawk-eagle was able to capture a black vulture (Coragyps atratus) that had come to the carcass of a monkey that the hawk-eagle itself may have also killed. In general, a picture has emerged that the ornate hawk-eagle is a particularly opportunistic predator, attracted to conspicuous prey behaviors and less deeply searching in its foraging than most co-existing forest eagles. Of particularly broad import to ornate hawk-eagles are the cracid family of gamebirds such as chachalacas, guans and curassows. In fact, local names refer to this species at times as the "guan hawk" or the "curassow hawk". At least twelve species of cracid are taken quite often where available (including the crested guan [Penelope purpurascens]), and this is probably only a partial list of the species they hunt. However, the ornate hawk-eagle is far from specialized on cracid prey and takes more or less any medium-sized or larger avian prey they opportune upon. In Tikal, Guatemala, the most often identified avian prey on 10 ornate hawk-eagle territories was the keel-billed toucan (Ramphastos sulfuratus), accounting for 11.3% of 408 prey items, followed by the plain chachalaca (Ortalis vetula) (6.5%) and great tinamou (Tinamus major) (4%) (in by far the largest dietary study conducted for this hawk-eagle). In total, birds were 56.3% of the foods for the species at the Tikal study. However, at both Tikal and Manaus, the most often identified prey species types were mammals. In Tikal, the similar Yucatan squirrel (Sciurus yucatanensis) and the Deppe's squirrel (Sciurus deppei) lead the food by number, accounting for 28.2% of the foods. Among mammals, these medium to fairly large rodents regardless of whether they show terrestrial (agoutis and similar species) or arboreal (tree squirrels) tendencies make up the largest known portion of the food, perhaps most key being partially diurnal habits. Another widely recorded mammalian prey group are procyonids despite a slight penchant for more nocturnal activity, including such prey as raccoon (Procyon lotor), white-nosed coati (Nasua narica), kinkajou (Poto flavus) and cacomistle (Bassariscus sumichrasti). Usually the hawk-eagles are likely to target juveniles of the larger species of procyonid, although adults at least up to the size of kinkajous may be taken. However, certainly the most well-studied mammalian prey for ornate hawk-eagles are New World monkeys, which they do not hunt necessarily seem to hunt preferentially. However, they are unlikely to ignore an opportunity to prey upon primates. Among monkeys, mainly those of a smaller size class are hunted, largely such groups as squirrel monkeys, tamarins, marmosets and titi monkeys are attacked. In most such monkey species, adults usually weigh less than , and juveniles may be slightly more regularly taken even for species this small. Larger primates, those averaging over , are on occasion vulnerable to predation by ornate hawk-eagles including white-faced sakis (Pithecia pithecia), Guatemalan black howler (Alouatta pigra) (certainly only juveniles of this very large howler monkey) and some species of capuchin monkey. Due to the range of predators that they attract given their relatively smaller size, monkeys in the neotropics are highly wary and have well-developed anti-predator defenses, especially a variety of alarm calls, grouping techniques, great arboreal agility and aggressive defensive attacks by top males, all of which make monkeys more difficult to attack than more solitary, terrestrial and/or slower-moving mammal prey of similar size. Relatively few mammalian prey are taken outside of rodents, procyonids and monkeys, but ornate hawk-eagles are also known to take Jamaican fruit bats (Artibeus jamaicensis), other leaf-nosed bats, a few species of opossum, silky anteaters (Cyclopes didactylus) and even apparently bush dogs (Speothos venaticus). Apart from mammals and birds, only rarely does the ornate hawk-eagle seem to hunt reptiles (i.e., lizards and unidentified snakes). In the Tikal study, mean prey size was estimated at , with avian prey averaging an estimated and mammal prey (which consisted largely of squirrels) averaging an estimated . Mammalian prey taken can reach an estimated in the case of a Central American agouti (Dasyprocta punctata). When capturing such large prey, ornate hawk-eagles are incapable of flying with them. In the case of agoutis and curassows killed in Tikal, the hawk-eagles would return repeatedly to feed on their kill, ultimately consuming about half of the bodies before decomposition sets in. A male ornate hawk-eagle that had killed a great tinamou of roughly equal weight to itself (both around ) was similarly grounded after being unable to fly with its kill (only consuming the head before being flushed by researchers). To the best knowledge of ornithologists and other researchers, the most likely form of partitioning comes in the form of the dietary preferences. Other (but not all) studies also indicate a preference for mammals of varying sizes (perhaps to the size of raccoons) in the diet of black hawk-eagles. Meanwhile, black-and-white hawk-eagles have been indicated to show a preference for slightly smaller birds than those selected by ornate hawk-eagles, such as medium-to-large passerines, pigeons and smallish toucans (such as aracaris and toucanets), though capable of preying on adult ducks and even monkeys quite as large as those taken by the ornate. Other eagle-like forest raptors such as solitary eagles (Buteogallus solitarius), whose mountainous range (similar to the black-and-chestnut) barely abuts the altitudinal range with ornate hawk-eagle, have strongly different dietary preferences (e.g., snakes) while other Buteogallus species tend to be much more aquatically based both in diet and habitat preferences. Overlap in the prey spectrum is known with both crested and harpy eagles, but dietary preferences differ considerably. In the harpy eagle, preferred prey are sloths (which have never been known to fall prey to ornate hawk-eagles) and larger sized New World monkeys. Meanwhile, the crested eagle seems to prefer intermediately sized mammals, including monkeys mostly between tamarin and capuchin monkey-sized, but to also seemingly take prey of more varied classes than other lowland forest eagles. In Tikal, like the black hawk-eagle, the crested eagle appears to prefer nocturnal mammals, mostly various opossums, and presumably has a more intensive searching method of hunting rather than the opportunistic hunting typical of the ornate species. The various forest eagles of the neotropics appear to be surprisingly tolerant of other species, with almost no aggressive interspecies interactions known in the literature. Indicating a lack of interspecies aggression, one active harpy eagle nest was set with a camera trap captured photographs of a pair of ornate hawk-eagles in a breeding display in the immediate vicinity of the nest, with both species apparently indifferent to each other's presence. == Breeding ==

Ornate hawk-eagles, like most but not all raptors, live solitarily or in pairs. In the much sparser population of the Atlantic Forest of Brazil, it was estimated that there was one pair per each . The Tikal studies shows evidence of pairs shifting their territorial boundaries, in some cases this has been apparently and surprisingly due to the intrusion of another ornate hawk-eagle. Per the study: "Perhaps in these formidably armed bird predators, territory occupants sometimes readjust their patterns of spatial use rather risk outright aggressive contest". The breeding season of ornate hawk-eagles normally falls between December and September in Central America, while it is largely in August–January in Brazil. In Trinidad and Tobago, nest building is around November while in Venezuela was reportedly in March. However, in captivity, at least one female has been known to lay a two egg clutch. In interspecies comparisons, Tikal studies showed that black hawk-eagles are independent slightly faster at around 12 months old but, like the ornate, also reach maturity roughly in the zone of 2 to 3 years of age while crested eagles take 22.7–30 months until independence and start breeding somewhere around 3 to 4 years of age. In many of the larger eagles, including the harpy eagle, whether tropical or temperate zone dwelling, the minimum age of maturity seems to be around 5 years of age and in some large Afro-tropical species, possibly ranges up to more than 7 years of age. == Status ==

The ornate hawk-eagle is, like many large birds of prey, probably naturally scarce. Currently the total population is estimated at between 13,300 and 33,300 individuals, a very small population considering the species' ample range. The species is locally extinct in several former parts of the range. It is thought to have gone extinct early due to increased extensive 19th century colonization in Tumbes, Peru as well as the Belém and probably the São Francisco regions of Brazil. More recently, the continued presence of breeding ornate hawk-eagles was considered doubtful or at critical threat level in western Ecuador and local biologists considered the species to be extirpated from Colima, Mexico. Increases or apparent breeding records of the species in new areas are likely not correlated to actual population increases but are more likely cases of the species being driven from adjacent areas as habitats become unacceptable, accounting for increased records of the species at drier forests (i.e., in Mexico) or in higher elevations (i.e., in Colombia). What were considered possible range expansions in different areas of Brazil, such as the Caatinga (Serra das Confusões National Park) and Rio Grande do Sul, as well as in northwestern Peru, may be more likely mere cases of more extensive bird surveying in previously little studied areas. The ornate hawk eagle has a status of rare but persisting on Panamanian islands, Coiba and Barro Colorado Island. The leading cause, by far, for the species decline is epidemic levels of deforestation. Declines are correlated to deforestation in most parts of the species' range, all the way from the northern limits in Mexico down to the southern limits in Argentina. Even where lands become protected, it is in many cases too late due to forest fragmentation prior to conservation, resulting in stands too fragmented to support extensive use by the ornate hawk-eagles. Beyond deforestation, human hunting is also causing declines of this species. Little overarching conservation efforts are known to have been implemented specifically pertaining to this species' declines, beyond the general retention and conservation of existing forests. == References ==