Eagle

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Eagle
Eagles together.jpg
From left to right, top row first: golden eagle (Aquila chrysaetos), brown snake eagle (Circaetus cinereus), solitary eagle (Buteogallus solitarius), black eagle (Ictinaetus malaiensis) and African fish eagle (Haliaeetus vocifer).
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Accipitriformes
Family: Accipitridae
Species

See text

Eagle is the common name for the golden eagle, bald eagle, and other birds of prey in the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. True eagles comprise the genus Aquila . Most of the 68 species of eagles are from Eurasia and Africa. [1] Outside this area, just 14 species can be found—two in North America, nine in Central and South America, and three in Australia.

Eagles are not a natural group but denote essentially any kind of bird of prey large enough to hunt sizeable (about 50 cm long or more overall) vertebrates.

Description

Eagles are large, powerfully-built birds of prey, with heavy heads and beaks. Even the smallest eagles, such as the booted eagle (Hieraaetus pennatus), which is comparable in size to a common buzzard (Buteo buteo) or red-tailed hawk (B. jamaicensis), have relatively longer and more evenly broad wings, and more direct, faster flight – despite the reduced size of aerodynamic feathers. Most eagles are larger than any other raptors apart from some vultures. The smallest species of eagle is the South Nicobar serpent eagle (Spilornis klossi), at 450 g (1 lb) and 40 cm (16 in). The largest species are discussed below. Like all birds of prey, eagles have very large hooked beaks for ripping flesh from their prey, strong, muscular legs, and powerful talons.

The beak is typically heavier than that of most other birds of prey. Eagles' eyes are extremely powerful. It is estimated that the wedge-tailed eagle has a visual acuity twice that of a typical human. [2] [3] [4] This acuity enables eagles to spot potential prey from a very long distance. This keen eyesight is primarily attributed to their extremely large pupils which ensure minimal diffraction (scattering) of the incoming light. Like most diurnal raptors, eagles have little ability to see ultraviolet light. [5] The female of all known species of eagles is larger than the male. [6] [7]

Eagles normally build their nests, called eyries, in tall trees or on high cliffs. Many species lay two eggs, but the older, larger chick frequently kills its younger sibling once it has hatched. The parents take no action to stop the killing. [8] [9] It is said that eagles fly above clouds but this is not true. Eagles fly during storms and glide from the wind's pressure. This saves the bird's energy. Due to the size and power of many eagle species, they are ranked at the top of the food chain as apex predators in the avian world. The type of prey varies by genus. The Haliaeetus and Icthyophaga eagles prefer to capture fish, though the species in the former often capture various animals, especially other water birds, and are powerful kleptoparasites of other birds. The snake and serpent eagles of the genera Circaetus , Terathopius , and Spilornis predominantly prey on the great diversity of snakes found in the tropics of Africa and Asia. The eagles of the genus Aquila are often the top birds of prey in open habitats, taking almost any medium-sized vertebrate they can catch. Where Aquila eagles are absent, other eagles, such as the buteonine black-chested buzzard-eagle of South America, may assume the position of top raptorial predator in open areas. Many other eagles, including the species-rich genus Spizaetus , live predominantly in woodlands and forests. These eagles often target various arboreal or ground-dwelling mammals and birds, which are often unsuspectingly ambushed in such dense, knotty environments. Hunting techniques differ among the species and genera, with some individual eagles having engaged in quite varied techniques based on their environment and prey at any given time. Most eagles grab prey without landing and take flight with it, so the prey can be carried to a perch and torn apart. [10]

The bald eagle is noted for having flown with the heaviest load verified to be carried by any flying bird, since one eagle flew with a 6.8 kg (15 lb) mule deer fawn. [11] [12] However, a few eagles may target prey considerably heavier than themselves; such prey is too heavy to fly with, thus it is either eaten at the site of the kill or taken in pieces back to a perch or nest. Golden and crowned eagles have killed ungulates weighing up to 30 kg (66 lb) and a martial eagle even killed a 37 kg (82 lb) duiker, 7–8 times heavier than the preying eagle. [10] [13] Authors on birds David Allen Sibley, Pete Dunne, and Clay Sutton described the behavioral difference between hunting eagles and other birds of prey thus (in this case the bald and golden eagles as compared to other North American raptors): [14]

They have at least one singular characteristic. It has been observed that most birds of prey look back over their shoulders before striking prey (or shortly thereafter); predation is after all a two-edged sword. All hawks seem to have this habit, from the smallest kestrel to the largest Ferruginous – but not the Eagles.

Among the eagles are some of the largest birds of prey: only the condors and some of the Old World vultures are markedly larger. It is regularly debated which should be considered the largest species of eagle. They could be measured variously in total length, body mass, or wingspan. Different lifestyle needs among various eagles result in variable measurements from species to species. For example, many forest-dwelling eagles, including the very large harpy eagle, have relatively short wingspans, a feature necessary for being able to maneuver in quick, short bursts through densely forested habitats. [10] Eagles in the genus Aquila, found almost exclusively in open country, are noted for their ability to soar, and have relatively long wings for their size. [10]

These lists of the top five eagles are based on weight, length, and wingspan, respectively. Unless otherwise noted by reference, the figures listed are the median reported for each measurement in the guide Raptors of the World [15] in which only measurements that could be personally verified by the authors were listed. [10]

RankCommon nameScientific nameBody mass
1 Philippine eagle Pithecophaga jefferyi8.3 kg (18+14 lb) (Average Weight)
2 Steller's sea eagle Haliaeetus pelagicus7.4 kg (16+14 lb) (Average Weight)
3 Harpy eagle Harpia harpyja6.35 kg (14 lb) (Average Weight)
4 White-tailed eagle Haliaeetus albicilla4.8 kg (10+12 lb) (Average Weight) [16]
5 Martial eagle Polemaetus bellicosus4.6 kg (10+14 lb) [16] (Average Weight)
RankCommon nameScientific nameTotal length
1 Philippine eagle Pithecophaga jefferyi100 cm (3 ft 3 in) [17]
2 Harpy eagle Harpia harpyja98.5 cm (3 ft 3 in)
3 Wedge-tailed eagle Aquila audax95.5 cm (3 ft 2 in)
4 Steller's sea eagle Haliaeetus pelagicus95 cm (3 ft 1 in)
5 Crowned eagle Stephanoaetus coronatus87.5 cm (2 ft 10 in)
RankCommon nameScientific nameMedian wingspan
1 White-tailed eagle Haliaeetus albicilla218.5 cm (7 ft 2 in)
2 Steller's sea eagle Haliaeetus pelagicus212.5 cm (7 ft 0 in)
3 Wedge-tailed eagle Aquila audax210 cm (6 ft 11 in) [18] [19]
4 Golden eagle Aquila chrysaetos207 cm (6 ft 9 in)
5 Martial eagle Polemaetus bellicosus206.5 cm (6 ft 9 in)

Habitat

The eagles are generally distributed in all types of habitats and nearly all parts of the world. The birds can be found in northern tundra to tropical rainforests and deserts. In North America, bald eagles and golden eagles are very common.

Distribution

Groups

Eagles are often informally divided into four groups. [lower-alpha 1] [22]

The snake eagles are placed in the subfamily Circaetinae. The fish eagles, booted eagles, and harpy eagles have traditionally been placed in the subfamily Buteoninae together with the buzzard-hawks (buteonine hawks) and harriers. Some authors may treat these groups as tribes of the Buteoninae; Lerner & Mindell [23] proposed separating the eagle groups into their own subfamilies of Accipitridae.

Fish eagles

Sea eagles or fish eagles take fish as a large part of their diets, either fresh or as carrion.

Proposed subfamily Haliaeetinae. Genera: Haliaeetus , Icthyophaga .

Some authors include Gypohierax angolensis, the "vulturine fish eagle" (also called the palm-nut vulture) in this group. [22] However, genetic analyses indicate it is related to a grouping of NeophronGypaetusEutriorchis (Egyptian vulture, bearded vulture (lammergeier), and Madagascar serpent eagle). [24]

The fish eagles have a close genetic relationship with Haliastur and Milvus ; the whole group is only distantly related to the Buteo group. [24]

Fish eagles exist in every continent throughout the world, except for South America. [25]

Booted eagles

Booted eagle in flight Booted eagle in flight.jpg
Booted eagle in flight

Booted eagles or "true eagles" [22] [26] have feathered tarsi (lower legs).

Tribe Aquililae or proposed subfamily Aquilinae. Genera: Aquila, Hieraaetus; Spizaetus, Oroaetus, Spizastur; Nisaetus; [24] Ictinaetus, Lophoaetus; Polemaetus; and Stephanoaetus. [22] [26]

See comments under eagle species for changes to the composition of these genera.

Snake eagles

Most snake or serpent eagles, as the name suggests, primarily prey on snakes.

Despite filling the niche of a snake eagle, genetic studies suggest that the Madagascar serpent eagle (Eutriorchis) is not related to them. [24]

Harpy eagles

Harpy eagles [22] or "giant forest eagles" [21] are large eagles that inhabit tropical forests. The group contains two to six species, depending on the author. Although these birds occupy similar niches and have traditionally been grouped, they are not all related: the solitary eagles are related to the black hawks and the Philippine eagle to the snake eagles.

Species

Martial eagle in Namibia Martial Eagle in Namibia.jpg
Martial eagle in Namibia
Philippine eagle (Pithecophaga jefferyi) in Southern Philippines Pithecophaga jefferyi.jpg
Philippine eagle (Pithecophaga jefferyi) in Southern Philippines
Wedge-tailed eagle in Australia WedgetailEagleCarrion.jpg
Wedge-tailed eagle in Australia
Eastern imperial eagle in Israel `yt nyTSy.jpg
Eastern imperial eagle in Israel

Major new research into eagle taxonomy suggests that the important genera Aquila and Hieraaetus are not composed of nearest relatives, and it is likely that a reclassification of these genera will soon take place, with some species being moved to Lophaetus or Ictinaetus. [23]

Family Accipitridae

Short-toed snake eagle in flight CircaetusGallicus.jpg
Short-toed snake eagle in flight

In culture

Eagles, a Chinese Ming period painting; Located at the National Palace Museum Lin Liang-Eagles.jpg
Eagles, a Chinese Ming period painting; Located at the National Palace Museum

Etymology

The modern English term for the bird is derived from Latin : aquila by way of French : aigle . The origin of aquila is unknown, but it is believed to possibly derive from aquilus (meaning dark-colored, swarthy, or blackish) as a reference to the plumage of eagles.

Old English used the term earn , related to Scandinavia's ørn/örn . It is similar to other Indo-European terms for "bird" or "eagle", including Greek : ὄρνις (ornís), Russian : орёл (orël), and Welsh : eryr.

In the southern part of Finland, near the Gulf of Finland, is the town of Kotka, which literally means "eagle", while the town of L'Aquila in the central part of Italy literally means "the eagle".

The sculpture of eagle at the top of the fountain at Plac Orla Bialego in Szczecin, Poland Fountain top.JPG
The sculpture of eagle at the top of the fountain at Plac Orła Białego in Szczecin, Poland

In Britain before 1678, eagle referred specifically to the golden eagle, with the other native species, the white-tailed eagle, being known as erne. The modern name "golden eagle" for aquila chrysaetos was introduced by the naturalist John Ray. [27]

The village of Eagle in Lincolnshire, England, has nothing to do with the bird; its name is derived from the Old English words for "oak" and "wood" (compare Oakley). [28]

Religion and spirituality

Representation of an eagle at Rio Carnival, 2014 Desfile Portela 2014 (906185).jpg
Representation of an eagle at Rio Carnival, 2014
Garuda, the vahana (mount) of Vishnu, depicted with an eagle's beak and wings Garuda by Hyougushi in Delhi.jpg
Garuda, the vahana (mount) of Vishnu, depicted with an eagle's beak and wings

In the ancient Sumerian mythology, the mythical king Etana was said to have been carried into heaven by an eagle. [29] Classical writers such as Lucan and Pliny the Elder claimed that the eagle was able to look directly at the sun, and that they forced their fledglings to do the same. Those that blinked would be cast from the nest. This belief persisted until the Medieval era. [30]

The eagle is the patron animal of the ancient Greek god Zeus. In particular, Zeus was said to have taken the form of an eagle in order to abduct Ganymede, and there are numerous artistic depictions of the eagle Zeus bearing Ganymede aloft, from Classical times up to the present (see illustrations in the Ganymede (mythology) page.) [31]

Eagles appear metaphorically in many translations of the Old Testament. God is spoken of as carrying Israel on "eagles' wings" in Exodus 19:4, Isaiah 40:31 compares those who wait on the Lord to flying eagles, and Psalm 103 mentions renewing one's youth "as the eagle". In explaining this rejuvenation, Augustine of Hippo says in his commentary on the Psalms that eagles' beaks overgrow as they age and that they break them against rocks to restore them. [32] The translation, however, is uncertain: the word in the Hebrew, נשר, can also be translated vulture, [33] and is listed alongside specific kinds of vulture in Leviticus' discussion of unclean animals.

The eagle is also often used in Christian iconography to represent the Gospel of John, [34] and eagle-shaped lecterns are common in Anglican and some Roman Catholic churches. [35] The eagle was believed to be able to look directly into the sun in the same way that the Gospel of John looks directly at Jesus' divinity, and the great distances the eagle flies represent the spread of the gospel to the ends of the earth.

The United States eagle feather law stipulates that only individuals of certifiable Native American ancestry enrolled in a federally recognized tribe are legally authorized to obtain eagle feathers for religious or spiritual reasons. [36] In Canada, the poaching of eagle feathers for the booming U.S. market has sometimes resulted in the arrests of First Nations person for the crime. [37]

The Moche people of ancient Peru worshiped the eagle and often depicted eagles in their art. [38]

Heraldry

Coat of arms of Austria. Coat of arms of Austria.svg
Coat of arms of Austria.
Kotka.vaakuna.svg
Coat of arms of Kotka, Finland
Greater coat of arms of the United States.svg
Coat of arms of the United States

Eagles are an exceptionally common symbol in heraldry, being considered the "King of Birds" in contrast to the lion, the "King of Beasts". Whereas the lion (e.g. England) usually represents authority, the eagle is the symbol of power. They are particularly popular in Germanic countries such as Austria, due to their association with the Holy Roman Empire. The eagle of the Holy Roman Empire was two-headed, supposedly representing the two divisions, East and West, of the old Roman Empire. This motif, derived from the Byzantine (Eastern Roman) Empire was also adopted by the Russian Empire and is still featured in the Flag of Albania. The Roman eagle was preceded by the eagle of Ptolemaic Egypt and the Achaemenid Empire. In the coat of arms of Kotka, Finland, the eagle is depicted carrying an anchor and the caduceus on its feet.

Heraldic eagles are most often found displayed, i.e. with their wings and legs extended. They can also occur close, i.e. with their wings folded, or rising, i.e. about to take flight. The heads, wings, and legs of eagles can also be found independently.

Notes

  1. "There are four major groups of eagles: fish eagles, booted eagles, snake eagles and giant forest eagles." [21]

Related Research Articles

<span class="mw-page-title-main">Accipitridae</span> Family of birds of prey

The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds of prey with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a few feeding on fruit. The Accipitridae have a cosmopolitan distribution, being found on all the world's continents and a number of oceanic island groups. Some species are migratory. The family contains 255 species which are divided into 70 genera.

<span class="mw-page-title-main">Booted eagle</span> Species of bird

The booted eagle is a medium-sized mostly migratory bird of prey with a wide distribution in the Palearctic and southern Asia, wintering in the tropics of Africa and Asia, with a small, disjunct breeding population in south-western Africa. Like all eagles, it belongs to the family Accipitridae.

<span class="mw-page-title-main">Buteoninae</span> Subfamily of birds

The Buteoninae are a subfamily of birds of prey which consists of medium to large, broad-winged species.

<span class="mw-page-title-main">Circaetinae</span> Subfamily of birds

Circaetinae is a bird of prey subfamily which consists of a group of medium to large broad-winged species. These are mainly birds which specialise in feeding on snakes and other reptiles, which is the reason most are referred to as "snake-eagles" or "serpent-eagles". The exceptions are the bateleur, a more generalised hunter, and the Philippine eagle, which preys on mammals and birds.

<span class="mw-page-title-main">Crested serpent eagle</span> Bird of prey from tropical Asia (Spilornis cheela)

The crested serpent eagle is a medium-sized bird of prey that is found in forested habitats across tropical Asia. Within its widespread range across the Indian Subcontinent, Southeast Asia and East Asia, there are considerable variations and some authorities prefer to treat several of its subspecies as completely separate species. In the past, several species including the Philippine serpent eagle, Andaman serpent eagle and South Nicobar serpent eagle were treated as subspecies of the Crested serpent eagle. All members within the species complex have a large looking head with long feathers on the back of the head giving them a maned and crested appearance. The face is bare and yellow joining up with the ceres while the powerful feet are unfeathered and heavily scaled. They fly over the forest canopy on broad wings and tail have wide white and black bars. They call often with a loud, piercing and familiar three or two-note call. They often feed on snakes, giving them their name and are placed along with the Circaetus snake-eagles in the subfamily Circaetinae.

<span class="mw-page-title-main">Verreaux's eagle</span> Species of bird

Verreaux's eagle is a large, mostly African, bird of prey. It is also called the black eagle, especially in southern Africa, not to be confused with the black eagle of south and southeast Asia. The Verreaux's eagle lives in hilly and mountainous regions of southern and eastern Africa, and very locally in the Middle East.

<span class="mw-page-title-main">Ornate hawk-eagle</span> Species of bird

The ornate hawk-eagle is a fairly large bird of prey from the tropical Americas. Formerly, some authorities referred to this species as the crested hawk-eagle, a name that may cause some confusion as it is more commonly used for an Asian eagle species. Like all eagles, it is in the family Accipitridae. This species has a feathered tarsus that marks it as a member of the Aquilinae or booted eagle subfamily. This species is notable for the vivid colors and bold markings of adults, which differ considerably from the far more whitish plumage of the juvenile bird. The ornate hawk-eagle ranges from central Mexico south through much of Central America and in a somewhat spotty but broad overall range into South America, including in the west apart from the Andes and broadly on the Atlantic side especially Brazil down to as far as Southeast Brazil and northern Argentina. This species is found largely in primary forests with tall trees, although can be found in many forest types.

<i>Aquila</i> (bird) Genus of birds

Aquila is the genus of true eagles. The genus name is Latin for "eagle", possibly derived from aquilus, "dark in colour". It is often united with the sea eagles, buteos, and other more heavyset Accipitridae, but more recently they appear to be less distinct from the slenderer accipitrine hawks than previously believed. Eagles are not a natural group but denote essentially any bird of prey large enough to hunt sizeable vertebrate prey.

<i>Spizaetus</i> Genus of birds

Spizaetus is the typical hawk-eagle birds of prey genus found in the tropics of the Americas. It was however used to indicate a group of tropical eagles that included species occurring in southern and southeastern Asia and one representative of this genus in the rainforests of West Africa. The Old World species have been separated into the genus Nisaetus. Several species have a prominent head crest. These are medium to large-sized raptors, most being between 55 and 75 cm long, and tend to be long-tailed and slender.

<i>Hieraaetus</i> Genus of birds

The genus Hieraaetus, sometimes known as small eagles or hawk-eagles, denotes a group of smallish eagles usually placed in the accipitrid subfamilies Buteoninae or Aquilinae.

<span class="mw-page-title-main">Congo serpent eagle</span> Species of bird

The Congo serpent eagle is a species of bird of prey in the family Accipitridae. It is the only member of the monotypic genus Dryotriorchis, although it was formerly placed in Circaetus. This species is distributed across the African tropical rainforest, including upper and lower Guinean forests. This serpent eagle specializes in hunting in these forests’ dark understories. It has two subspecies, the nominate subspecies Dryotriorchis spectabilis spectabilis and Dryotriorchis spectabilis batesi. Though monotypic, it appears to be very closely related to Circaetus. This hawk is a medium-sized bird with distinctive short, rounded wings and a long, rounded tail. It is varying shades of brown on its back and has a slight crest. Its breast is white with variable amounts of a rufous wash and, in the nominate subspecies, is covered in round, blackish spots. The subspecies D. s. batesi only has these dots on its flanks. The Congo serpent eagle closely resembles Cassin's hawk-eagle, and some ornithologists believe that this likeness is a rare example of avian mimicry. It is a very vocal raptor, and often is one of the most heard species in its habitat.

<span class="mw-page-title-main">Pygmy eagle</span> Species of bird

The pygmy eagle or New Guinea hawk-eagle is a bird of prey found in New Guinea. Its natural habitats are primarily subtropical or tropical moist lowland forest and subtropical or tropical moist montane forest. It is the smallest species of eagle.

<span class="mw-page-title-main">Black-and-chestnut eagle</span> Species of bird

The black-and-chestnut eagle is a large South American species of bird of prey in the family Accipitridae. It is sometimes called Isidor's eagle. It is often placed in the monotypic genus Oroaetus. However, recent genetic testing indicates that this species is fairly closely related to Spizaetus species and thus the species should be included in that genus. The black-and-chestnut eagle is a typical forest raptor, hunting primarily small to medium-sized mammals and birds and constructing a large nest in a tall tree. Unfortunately, the twin causes of habitat destruction and persecution, justified or not as an occasional poultry killer, have caused strong population declines and the black-and-chestnut eagle is considered to be an Endangered species by the IUCN.

<span class="mw-page-title-main">Andaman serpent eagle</span> Eagle species (Spilornis elgini) from the Andaman Islands

The Andaman serpent eagle, also known as the Andaman dark-serpent eagle or the dark serpent eagle, is a medium-sized bird in the family Accipitridae, the raptor family, that is only found in India on the Andaman Islands. It is currently classified as vulnerable and is experiencing population declines. This species, unlike the Crested serpent eagle, is incredibly understudied and so many things about its behaviour and ecology are still widely unknown.

<i>Spilornis</i> Genus of birds

Spilornis is a genus of bird of prey in the family Accipitridae. As adults all have dark crowns, and bright yellow eyes and cere. These medium-sized raptors are found in forests of southern Asia and are known as serpent-eagles; an English name shared with two African species from the genera Dryotriorchis and Eutriorchis.

<span class="mw-page-title-main">Cassin's hawk-eagle</span> Species of bird

Cassin's hawk-eagle or Cassin's eagle, is a relatively small eagle in the family Accipitridae. Its feathered legs mark it as member of the Aquilinae or booted eagle subfamily. A forest-dependent species, it occurs in primary rainforests across western, central and (marginally) eastern Africa where it preys on birds and tree squirrels. It was named after John Cassin who first described it in 1865. Due to widespread habitat destruction, its populations are steadily declining but have not yet warranted upgrading its status from Least Concern.

<span class="mw-page-title-main">Aquilinae</span> Subfamily of birds

The Aquilinae are a subfamily of eagles of the family Accipitridae. The general common name used for members of this subfamily is "booted eagle", although this is also the common name of a member of the subfamily. At one point, this subfamily was considered inclusive with the Buteoninae based probably on some shared morphological characteristics. However, research on the DNA of the booted eagles has shown that they are a monophyletic group that probably have had millions of years of separation from other extant forms of accipitrid.

Booted eagles are eagles that have fully feathered tarsi. That is, their legs are covered with feathers down to the feet. Most other accipitrids have bare lower legs, scaled rather than feathered.

<span class="mw-page-title-main">Crowned eagle</span> Species of bird

The crowned eagle, also known as the African crowned eagle or the crowned hawk-eagle, is a large bird of prey found in sub-Saharan Africa; in Southern Africa, it is restricted to more easterly areas. Its preferred habitats are principally riparian woodlands and various forests. The crowned eagle is the only extant member of the genus Stephanoaetus. A second species, the Malagasy crowned eagle, went extinct after early humans settled on Madagascar.

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