>>Genus Spizastur >Spizastur melanoleucus (Black-and-white Hawk-Eagle)

Black-and-white Hawk-Eagle

Black-and-white Hawk-Eagle
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Falconiformes (or Accipitriformes, q.v.)
Family:	Accipitridae
Genus:	Spizaetus
Species:	S. melanoleucus
Binomial name
Spizaetus melanoleucus (Vieillot, 1816)
Synonyms
Buteo melanoleucus Vieillot, 1816 Spizastur melanoleucus (Vieillot, 1816)

The Black-and-white Hawk-Eagle (Spizaetus melanoleucus, formerly Spizastur melanoleucus) is a bird of prey species in the eagle and hawk family (Accipitridae). It is found throughout a large part of tropical America, from southern Mexico to northern Argentina.

Description

As its name suggest, this is a black and white eagle, resembling the small typical eagles sometimes separated in "Hieraaetus". It is some 20-24 in (50–60 cm) long overall and weighs about 30 oz (850 g). The head, neck and body are white; a small crest forms a black spot on top of the head, and the area around the eyes, particularly towards the bill, is also black. The wings are black, and the bird has a brownish tail barred black-dark grey and with white tip. Theiris is orange, the feet pale to bright yellow with black talons. The bill is black with a yellowcere.

The sexes are alike in color, but the female is larger. Immature birds have pale edges on the upperwing coverts and some brownish-grey feathers on the back.

The Black-and-white Hawk-Eagle is hard to confuse with any other bird in its range. The Black-faced Hawk (Leucopternis melanops) is very similar in overall coloration, but it is much smaller and has a black tail with a single bold white bar in the middle. The Ornate Hawk-Eagle(Spizaetus ornatus), presumably a very close relative of S. melanoleucus, looks quite similar when young. However, the wings, back and tail are much lighter in young S. ornatus, and they do not have the black eye-ring.

Distribution and ecology

This species occurs from Oaxaca to Veracruz in southern Mexico southwards throughout Central America, with the exception of most of El Salvador and the Pacific coast of Nicaragua. In South America, it occurs on the Pacific side of the Andes south to Ecuador. The bulk of its range extends along the Caribbean coast from northern Colombia and Venezuela to the Guianas, and south through eastern Brazil, Paraguay and Uruguay to NE Argentina, and from there westwards again to Beni and Santa Cruz in NE Bolivia. A Black-and-white Hawk-Eagle population is also found in the Loreto Region of NE Peru; it is not known in how far this is isolated from the rest of the bird's range. The species is absent from western Amazonia, and it is not common in the lands to the east (e.g. in Minas Gerais).

Its natural habitats are lowland forests of any type, though very dense and humid as well as savanna-like semiarid habitat are not preferred.Habitat fragmentation is not very well tolerated; though the species prefers a diverse habitat of mixed forest and shrubland, it requires large stands of closed-canopy forest to thrive. Its range does not extend very far into the uplands, but one individual was sighted at an altitude of about 4,000 ft (c.1,200 m) ASL in the Buena Vista Nature Reserve in Colombia's Sierra Nevada de Santa Marta.

The food of this carnivore consists of mammals, toads, squamates and in particular a wide variety of birds. Among the latter, it is known to prefer tree-living species, such as oropendolas, aracaris, tanagers and cotingas. But ground- and waterbirds like tinamous, chachalacas,cormorants and the highly threatened Brazilian Merganser (Mergus octosetaceus) have also been recorded as its prey. The Black-and-white Hawk-Eagle has been known to attack small monkeys, though it is not clear with which intent. For as it seems, it has not been recorded to actually kill and eat a monkey.

Its preferred hunting technique is to soar high until it has spotted suitable prey, and then dive down on it, usually right into the forest canopy, but it has also been observed to catch a White Woodpecker (Melanerpes candidus) that had been mobbing it in mid-air, after launching itself from its perch. It likes to hunt along ridges and forest edges where it can access the canopy-level from an oblique direction rather than just from directly above, and where ground-living prey is also more accessible.

It nests in the forest canopy, building a stick nest high up in exposed trees on ridges and similar locations, from where good hunting grounds can be watched. Detailed observations on its nesting habits are nearly non-existent however. In Panama, birds started to construct a nest in September, during a dry spell in the rainy season. But the main nesting season may start before the onset of the rainy season as the nesting attempt was abandoned when heavy rains recommenced. The scant other data agrees with this, and at least in Central America the nesting season seems to run from March to June or so.

There is a general lack of information on the Black-and-white Hawk-Eagle's movements and population status. Each bird seems to require a hunting territory of about 3,500 acres (1,400 hectars) at least. While the variety of habitat types in which it is found suggests that it is not particularly susceptible to changes in land use, it is apparently still a rare and local species almost anywhere in its range. The IUCN until 2000 classified it as a Near Threatened species due to the uncertainties surrounding its status, but as no evidence of a marked decline has been found and as the bird is found across a wide range, it was downlisted to a Species of Least Concern.

Taxonomy and systematics

This species is often placed in the monotypic genus Spizastur, but has recently been moved to Spizaetus e.g. by the American Ornithologists' Union, as it appears that the Ornate Hawk-Eagle (S. ornatus) is its sister taxon.This has created quite some taxonomic confusion, which has largely gone unnoticed however:

Originally, the name Spizaetus melanoleucus was given by Louis Jean Pierre Vieillot to the Black-chested Buzzard-eagle in 1819, while the Black-and-white Hawk-Eagle had been described in 1816 by the very same scientist as Buteo melanoleucus. The former species was placed inGeranoaetus – also a monotypic genus – in 1844, while the Black-and-white Hawk-Eagle had been moved out of Buteo and into Spizastur a few years earlier.

Thus, the identical specific epithets never came into direct conflict until recently. But the Black-chested Eagle-buzzard's placement in a monotypic genus was always disputed, and several authors treated it in Buteo.However, they overlooked that Buteo melanoleucus was the original name of the Black-and-white Hawk-Eagle and thus as a senior homonym could not be applied to the later-described species. The correct specific name for the Black-chested Eagle-buzzard when placed in Buteo, Buteo fuscescens, was reestablished in the mid-20th century for a short time more by accident than anything else;as most late-20th-century researchers argued for retaining Geranoaetus, this name was dismissed as erroneous and essentially forgotten.

As the Black-and-white Hawk-Eagle has not been placed in Buteo since long, Article 59.3 of the ICZN Code applies. According to this, a junior homonym replaced before 1961 is not rendered permanently invalid (as junior homonyms usually are) if "the substitute name is not in use"– which has been the case after Amadon's 1963 revision. Hence, in this case the scientific name Buteo melanoleucus can apply to the Black-chested Eagle-buzzard, even though the Black-and-white Hawk-Eagle was described under exactly that name earlier, while the senior homonym melanoleucus still applies to the latter species when placed in Spizaetus according to the usual ICZN rules. Consequently, the proper name to use for each bird has through a number of coincidences become the senior synonym of the other species.

>>Genus Oroaetus >Oroaetus isidori (Black-and-chestnut Eagle)

Black-and-chestnut Eagle

Black-and-chestnut Eagle
Conservation status
Near Threatened (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Falconiformes (or Accipitriformes, q.v.)
Family:	Accipitridae
Genus:	Spizaetus
Species:	S. isidori
Binomial name
Spizaetus isidori (Des Murs, 1845)
Synonyms
Oroaetus isidori (Des Murs, 1845)

The Black-and-chestnut Eagle (Spizaetus isidori) is a South American species of bird of prey in the Accipitridae family. It is sometimes called Isidor's Eagle. It is often placed in the monotypicgenus Oroaetus.

This is a fairly large eagle at 63–74 cm (25–29 in) long with a wingspan of 147–166 cm (58–66 in). As an adult, this species is glossy black on the head and the back and a streaky chestnut on the underside, much of the wing primaries and legs. The juvenile bird is very different, being whitish over the head and body with a buffy wash underneath and scaly gray on the back and wings. Nest building is February and March, laying eggs in April and May and fledging young by August and September. It builds a huge stick nest about 2 m (6.6 ft) across and 1 m (3.3 ft) deep. Clutches include 1 to 2 fledgings. At the nest area, adults primarily bring squirrels to their young.

They are known to prey on woolly monkeys, porcupines, coatis and other mid-sized arboreal mammals. Large birds such as guans are also taken. They frequently have much abraded tails by plunging after prey through the branches. They overlap in range with several other large forest eagles, including Solitary Eagle and possibly other Spizaetus eagles, but no interactions have been reported and the Black-and-chestnut Eagle is believed to be normally the top avian predator in its range.

It is found humid montane forests, normally at elevations between 1,800-2,500 meters, in theAndes from northern Argentina, through Bolivia, Peru, Ecuador, Colombia, to Venezuela, with isolated populations in the Venezuelan Coastal Range, Serranía del Perijá and Sierra Nevada de Santa Marta. It is generally local and rare.

>>Genus Harpyopsis (Papuan Eagle)

Papuan Eagle

Papuan Eagle
Conservation status
Vulnerable (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Accipitriformes
Family:	Accipitridae
Genus:	Harpyopsis Salvadori, 1875
Species:	H. novaeguineae
Binomial name
Harpyopsis novaeguineae Salvadori, 1875

The Papuan Eagle (Harpyopsis novaeguineae) also known as the Papuan Harpy Eagle, New Guinea Eagle, or Kapul Eagle, is a huge (up to 90 cm long) greyish brown raptor with a short full crest, broad three-banded wings, powerful beak, large iris, long rounded tail and white underparts. It has long and powerful unfeathered legs with sharp claws. The sexes are similar, and the female is slightly larger than the male. It is the only member of the monotypic genus Harpyopsis.

The Papuan Eagle is endemic to undisturbed tropical rainforests of New Guinea, where it became the top predator of the island. The diet consists mainly of phalangers or Kapul in a local language, hence its alternative name. It also feeds on other mammals, birds and snakes.

One of a group of four large eagles, the others being the Crested and Harpy Eagle of South America and the Philippine Eagle of the Philippines, the New Guinea Harpy Eagle is essentially a mountain bird that nests in high forest trees.

Due to ongoing habitat loss, small population size, and hunting for its feathers which are used on ceremonial occasions, the Papuan Eagle is evaluated as Vulnerable on the IUCN Red List of Threatened Species. It is listed on Appendix II of CITES.

>>Genus Pithecophaga (Philippine Eagle)

Philippine Eagle

Philippine Eagle
Conservation status
Critically Endangered (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Falconiformes (or Accipitriformes, q.v.)
Family:	Accipitridae
Genus:	Pithecophaga Ogilvie-Grant, 1896
Species:	P. jefferyi
Binomial name
Pithecophaga jefferyi Ogilvie-Grant, 1897
Range in blue green

The Philippine Eagle (Pithecophaga jefferyi), also known as the Monkey-eating Eagle, is an eagle of the family Accipitridae that is endemic to forests in the Philippines. It has brown and white-coloured plumage, and a shaggy crest, and generally measures 86 to 102 centimetres (2.82 to 3.35 ft) in length and weighs 4.7 to 8 kilograms (10 to 18 lb). Among the rarest, largest, and most powerful birds in the world, it has been declared the Philippine national bird. It is critically endangered, mainly due to massive loss of habitat due to deforestation in most of its range. Killing a Philippine Eagle is punishable under Philippine law by twelve years in jail and heavy fines.

Taxonomy

The first European to discover the species in 1896 was the English explorer and naturalist John Whitehead, who observed the bird and whose servant, Juan, collected the first specimen a few weeks later.The skin of the bird was sent to William Robert Ogilvie-Grant in London in 1896, who initially showed it off in a local restaurant and described the species a few weeks later.

Upon its discovery, the Philippine Eagle was first called the monkey-eating eagle because of reports from natives of Bonga, Samar, where the species was first discovered, that it preyed exclusively on monkeys; from these reports it gained its generic name, from the Greek pithecus ("ape or monkey") and phagus ("eater of"). The specific name commemorates Jeffery Whitehead, the father of John Whitehead. Later studies revealed, however, that the alleged monkey-eating eagle also ate other animals such as colugo, civets, large snakes, monitor lizards, and even large birds like hornbills. This, coupled with the fact that the same name applied to the African Crowned Eagleand the Central and South American Harpy Eagle, resulted in a presidential proclamation to change its name to Philippine Eagle in 1978, and in 1995 was declared a national emblem. This species has no recognized subspecies.

Apart from Philippine Eagle and Monkey-eating Eagle, it has also been called the Great Philippine Eagle. It has numerous local names, including agila ("eagle"), haribon, haring ibon ("bird king") andbanog ("kite").

Evolutionary history

A study of the skeletal features in 1919 led to the suggestion that the nearest relative was theHarpy Eagle. The species was included in the subfamily Harpiinae until a 2005 study of DNAsequences which identified them as non-members of the group, finding instead, that the nearest relatives are snake eagles (Circaetinae) such as the Bateleur. The species has subsequently been placed in the subfamily Circaetinae.

Description

The Philippine Eagle's nape is adorned with long brown feathers that form a shaggy crest. These feathers give it the appearance of possessing a lion's mane, which in turn resembles the mythicalgriffin. The eagle has a dark face and a creamy-brown nape and crown. The back of the Philippine Eagle is dark brown, while the underside and underwings are white. The heavy legs are yellow with large, powerful dark claws, and the prominent large, high-arched, deep beak is a bluish-gray. The eagle's eyes are blue-gray. Juveniles are similar to adults except that their upperpart feathers have pale fringes.

The Philippine Eagle is typically reported as being 86–102 centimetres (2.82–3.35 ft) long, but a survey at several of the largestnatural history collection in the world found that the average was 95 centimetres (3.12 ft) for males and 105 centimetres (3.44 ft) for females. Based on the latter measurements, this makes it the longest extant species of eagle, as the average for the female equals themaximum reported for the Harpy Eagle and Steller's Sea Eagle.The longest Philippine Eagle reported anywhere and the longest eagle outside of the extinct Haast's Eagle is a specimen of unknown sex at the Field Museum of Natural History (FMNH) that is 112 centimetres (3.67 ft), but it had been kept in captivity and therefore may not represent the wild individuals due to differences in the food availability.The level of sexual dimorphism in size is not certain, but it is believed that the male typically is about 10% smaller than the female and this is supported by the average length provided for males and females in one source.For adult Philippine Eagles, the complete weight range has been reported as 4.7 to 8 kilograms (10 to 18 lb), while others have found that the average was 4.5 kilograms (9.9 lb) for males and 6 kilograms (13 lb) for females. It has a wingspan of 184 to 202 centimetres (6.04 to 6.63 ft). The maximum reported weight is surpassed by two other eagles (the Harpy and Steller's Sea Eagle) and the wings are shorter than large eagles of open country (such as the Martial Eagle, Wedge-tailed Eagle and Steller's Sea Eagle), but are quite broad.

The most frequently heard noises made by the Philippine Eagle are loud, high-pitched whistles ending with inflections in pitch. Additionally, juveniles have been known to beg for food by a series of high-pitched calls.

Distribution and habitat

The Philippine Eagle is endemic to the Philippines and can be found on four major islands: eastern Luzon, Samar, Leyte and Mindanao. The largest number of eagles reside on Mindanao, with between 82 and 233 breeding pairs. Only six pairs are found on Samar, two on Leyte, and a few on Luzon. It can be found in Northern Sierra Madre National Park on Luzon and Mount Apo and Mount Kitanglad National Parks on Mindanao.

This eagle is found in dipterocarp and mid-montane forests, particularly in steep areas. Its elevation ranges from the lowlands to mountains of over 1,800 metres (5,900 ft). It is estimated that only 9,220 square kilometers (2,280,000 acres) of old growth forest remain in the bird's range. However, its total estimated range is about 146,000 square kilometers (56,000 sq mi).

Ecology and behavior

Evolution in the Philippine islands, without other predators, made the eagles the dominant hunter in the Philippine forests. Each breeding pair requires a large home range to successfully raise a chick, and thus the species is extremely vulnerable to deforestation. Earlier it has been estimated that the territory is about 100 square kilometres (39 sq mi), but a study on Mindanao Island found the nearest distance between breeding pairs to be about 13 kilometres (8.1 mi) on average, resulting in a circular plot of 133 square kilometres (51 sq mi).

The species' flight is fast and agile, resembling the smaller hawks more than similar large birds of prey.

Juveniles in play behavior have been observed gripping knotholes in trees with their talons and, using its tail and wings for balance, inserting its head into a tree cavity.Additionally, they have been known to attack inanimate objects for practice as well as attempt to hang upside down to work on their balance. As the parents are not nearby when this occurs, it has been suggested that they do not play a role in teaching the juvenile to hunt.

Life expectancy for a wild eagle is estimated to be anywhere from 30 to 60 years. A captive Philippine Eagle lived for 41 years in Rome Zoo, and it was already adult when it arrived at the zoo. However, it is believed that wild birds on average live shorter lives than captive birds.

Diet

The Philippine Eagle was known initially as the Philippine Monkey-Eating Eagle because it was believed to feed on monkeys (the only monkey native to the Philippines is the Philippine long-tailed macaque) exclusively; this has proven to be inaccurate. The primary prey varies from island to island depending on species availability, particularly in Luzon and Mindanao. This is due to the islands being in different faunal regions. For example, Philippine flying lemurs, the preferred prey in Mindanao, are absent in Luzon. The primary prey for the eagles seen in Luzon are monkeys, birds, flying foxes, giant cloud-rats Phloeomys pallidus which can weigh twice as much as flying lemurs (that is, 2 to 2.5 kg), and reptiles such as large snakes and lizards. The eagles prefer flying lemurs and Asian Palm Civets, but they occasionally eat small mammals, birds (owls and hornbills), reptiles (snakes and monitor lizards), and even other birds of prey. There have been reports of eagles capturing young pigs and small dogs. It is estimated that the flying lemur could make up 90% of the raptor's diet in some locations.

Eagle pairs sometimes hunt troops of monkey cooperatively, with one bird perching nearby to distract the primates allowing the other to swoop in unnoticed for the kill.

Reproduction

A Philippine Eagle nestling

The complete breeding cycle of the Philippine Eagle lasts two years. The female matures sexually at five years of age and the male at seven. Like most eagles, the Philippine Eagle is monogamous. Once paired, a couple remains together for the rest of their lives. If one dies, the remaining eagle often searches for a new mate to replace the one lost.

The beginning of courtship is signaled by nest-building and the eagle remaining near its nest. Aerial displays also play a major role in the courtship. These displays include paired soaring over a nesting territory, the male chasing the female in a diagonal dive, and mutual talon presentation, where the male presents his talons to the female's back and she flips over in mid-air to present her own talons. Advertisement displays coupled with loud calling have also been reported. The willingness of an eagle to breed is displayed by the eagle bringing nesting materials to the bird's nest. Copulation follows and occurs repeatedly both on the nest and on nearby perches. The earliest courtship has been reported in July.

Breeding begins between September and February; birds on different islands, most notably Mindanao and Luzon, begin breeding at different ends of this range. The amount of rainfall and population of prey may also affect the breeding season. The nest is normally built on an emergent dipterocarp, or any tall tree with an open crown, in primary or disturbed forest and may be nearly 1.5 metres (4.9 ft) across and about 30 metres (98 ft) above the ground. The eagle's nest resembles a huge platform made of sticks. The eagle frequently reuses the same nesting site for several different chicks. Eight to ten days before the egg is ready to be laid, the female is afflicted with a condition known as egg lethargy. In this experience, the female does not eat, drinks lots of water, and holds its wings droopingly. The female typically lays one egg in the late afternoon or at dusk, although occasionally two have been reported.If an egg fails to hatch or the chick dies early, the parents will likely lay another egg the following year. Copulation may last a few days after the egg is laid to enable another egg to be laid should the first one fail. The egg is incubated for 58 to 68 days after being laid. Both sexes participate in the incubation, but the female does the majority of incubating during the day and all of it at night.

Both sexes help feed the newly hatched eaglet. Additionally, the parents have been observed taking turns shielding the eaglet from the sun and rain until it is seven weeks old. The young eaglet fledges after four or five months. The earliest an eagle has been observed making a kill is 304 days after hatching. Both parents take care of the eaglet for a total of twenty months.

Conservation

A Philippine Eagle named Sir Arny, at Philippine Eagle Center, Davao City.

In 2010, the IUCN and BirdLife International listed this species as critically endangered. TheInternational Union for the Conservation of Nature believes that between 180 and 500 Philippine Eagles survive in the Philippines.They are threatened primarily by deforestation through logging and expanding agriculture. Old growth forest is being lost at a high rate, and most of the eagle's forest in the lowlands is owned by logging companies.Mining, pollution, exposure to pesticides that affect breeding, and poaching are also major threats. Additionally, they are occasionally caught in traps laid by local people for deer. Though this is no longer a major problem, the eagle's numbers were also reduced by being captured for zoos.

The diminishing numbers of the Philippine Eagle were first brought to international attention in 1965 by the noted Filipino ornithologist, Dioscoro S. Rabor, and the then director of the Parks and Wildlife Office, Jesus A. Alvarez. Charles Lindbergh, best known for crossing the Atlantic alone and without stopping in 1927, was fascinated by this eagle. As a representative of the World Wildlife Fund, Lindbergh traveled to the Philippines several times between 1969 and 1972, where he helped persuade the government to protect the eagle. In 1969, the Monkey-eating Eagle Conservation Program was started to help preserve this species. In 1992, the first Philippine Eagles were born in captivity through artificial insemination; however, it was not until 1999 that the first naturally bred eaglet hatched. The first captive-bred bird to be released in the wild, Kabayan, was released in 2004 on Mindanao; however, he was accidentally electrocuted in January 2005. Another eagle, Kagsabua, was released March 6, 2008, but was shot and eaten by a farmer. Killing this critically endangered species is punishable under Philippine law by twelve years in jail and heavy fines.

Its numbers have slowly dwindled over the decades to the current population of 180 to 500 eagles. A series of floods and mud slides, caused by deforestation, further devastated the remaining population. The Philippine Eagle may soon no longer be found in the wild, unless direct intervention is taken. The Philippine Eagle Foundation of Davao City, Mindanao is one organization dedicated to the protection and conservation of the Philippine Eagle and its forest habitat. The Philippine Eagle Foundation has successfully bred Philippine Eagles in captivity for over a decade and conducted the first experimental release of a captive-bred eagle to the wild. The foundation has 32 eagles at its center, of which 18 were bred in captivity.Ongoing research on behavior, ecology and population dynamics is also underway. In recent years protected lands have been established specifically for this species, such as the 700 square kilometers (170,000 acres) Cabuaya Forest and the 37.2 square kilometers (9,200 acres) Taft Forest Wildlife Sanctuary on Samar.However, a large proportion of the population is found on unprotected land.

Relationship with humans

Illustration of a bird kept in captivity in London in 1909–1910

The Philippine Eagle was officially declared the national bird of the Philippines on 4 July 1995 by President Fidel V. Ramos under Proclamation No. 615.This eagle, because of its size and rarity, is also a highly desired bird for birdwatchers.

The Philippine Eagle has also featured on at least twelve stamps from the Philippines, with dates ranging from 1967 to 2007. It was also depicted on the 50 centavo coins minted from 1981 to 1994.

Historically, about 50 Philippine Eagles have been kept in zoos in Europe (England, Germany,Belgium, Italy and France), United States and Japan.The first was a female that arrived inLondon Zoo in August 1909 and died there in February 1910. The majority arrived in zoos between 1947 and 1965. The last outside the Philippines died in 1988 in the Antwerp Zoowhere it had lived since 1964 (except for a period at the Planckendael Zoo in Belgium).The first captive breeding was only achieved in 1992 at the facility of the Philippine Eagle Foundation in Davao City, Mindanao, the Philippines, which has bred it several times since then.

>>Genus Parabuteo (Harris's Hawk)

Harris's Hawk

Harris's Hawk
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Accipitriformes
Family:	Accipitridae
Subfamily:	Buteoninae
Genus:	Parabuteo Ridgway, 1874
Species:	P. unicinctus
Binomial name
Parabuteo unicinctus (Temminck, 1824)
Subspecies
P. u. harrisi P. u. superiorP. u. unicinctus

The Harris's Hawk or Harris Hawk (Parabuteo unicinctus) formerly known as the Bay-winged Hawk or Dusky Hawk, is a medium-large bird of prey which breeds from the southwestern United States south to Chile and central Argentina. Birds are sometimes reported at large in Western Europe, especially Britain, but it is a popular species in falconry and these records almost certainly all refer to escapes from captivity.

It is the only member of the genus Parabuteo. The name is derived from the Greek para, meaning beside, near or like, and the Latin buteo, referring to a kind of buzzard; uni meaning once; andcinctus meaning girdled, referring to the white band at the tip of the tail. John James Audubongave this bird its English name in honor of his ornithological companion, financial supporter, and friend Edward Harris.The Harris Hawk is notable for its behavior of hunting cooperatively in "packs", consisting of family groups while most other raptors hunt in solitary.

Description

Adult male

Individual Harris Hawks range in length from 46 to 76 cm (18 to 30 in) and generally have a wingspan of about 1.1 m (3.6 ft)They exhibit sexual dimorphism with the females being larger by about 35%. In the United States, the average weight for males is about 710 g (25 oz), while the female average is 1,020 g (36 oz).They have dark brown plumage with chestnut shoulders, wing linings, and thighs, white on the base a tip of the tail,long, yellow legs and a yellow cere. The vocalizations of the Harris's Hawk are very harsh sounds.

Juvenile

Juvenile in a falconry demonstration

The juvenile Harris Hawk is mostly streaked with buff, and appears much lighter than the dark adults. When in flight, the undersides of the juveniles' wings are buff-colored with brown streaking. They can look unlike adults at first glance, but the identical chestnut plumage is an aid for identification.

Subspecies

There are three subspecies of Harris's Hawk:

• P. u. superior: found in Baja California, Arizona, Sonora, and Sinaloa. P. u. superior was believed to have longer tails and wings and to be more blackish than P. u. harrisi. However, the sample size of the original study was quite small, with only five males and six females. Later research has concluded that there is not as strong a physical difference as was originally assumed. Other ecological differences, such as latitudinal cline were also brought up as arguments against the validity of the subspecies segmentation.
• P. u. harrisi: found in Texas, eastern Mexico, and much of Central America.
• P. u. unicinctus: found exclusively in South America. It is smaller than the North American subspecies.

Distribution and habitat

Harris's Hawks live in sparse woodland and semi-desert, as well as marshes (with some trees) in some parts of their range (Howell and Webb 1995), including mangrove swamps, as in parts of their South American range.Harris's Hawks are permanent residents and do notmigrate.

Behavior

At one week old, north Cheshire, England1

Feeding

The diet of the Harris's Hawk consists of small creatures including birds, lizards, mammals, and large insects. Because it often hunts in groups, the Harris's Hawk can also take down larger prey, such as jackrabbits.

Breeding

They nest in small trees, shrubby growth, or cacti. The nests are often compact, made of sticks, plant roots, and stems, and are often lined with leaves, moss, bark and plant roots. They are built mainly by the female. There are usually two to four white to blueish white eggs sometimes with a speckling of pale brown or gray. The nestlings start out light buff, but in five to six days turn a rich brown.

Very often, there will be three hawks attending one nest: two males and one female.Whether or not this is polyandry is debated, as it may be confused with backstanding (one bird standing on another's back). The female does most of the incubation. The eggs hatch in 31 to 36 days. The young begin to explore outside the nest at 38 days, and fledge, or start to fly, at 45 to 50 days. The female sometimes breeds two or three times in a year.Young may stay with their parents for up to three years, helping to raise later broods.

Relationship with humans

Adult male

Hunting

While most raptors are solitary, only coming together for breeding and migration, Harris's Hawks will hunt in cooperative groups of two to six. This is believed to be an adaptation to the desert climate in which they live. In one hunting technique, a small group flies ahead and scouts, then another group member flies ahead and scouts, and this continues until prey is bagged and shared. In another, all the hawks spread around the prey and one individual flushes it.

The wild Harris's Hawk population is declining due to habitat loss; however, under some circumstances, they have been known to move into developed areas.

Falconry

Since about 1980, Harris's Hawks have been increasingly used in falconry and are now the most popular hawks in the West (outside of Asia) for that purpose, as they are the easiest to train and the most social.

Training to catch rabbits

In art

John James Audubon illustrated the Harris's Hawk in Birds of America (published, London 1827–38) as Plate 392 with the title "Louisiana Hawk -Buteo harrisi". The image was engraved and colored by the Robert Havell, London workshops in 1837. The original watercolor by Audubon was purchased by the New York History Society where it remains to this day (January 2009).