Booted eagles

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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.

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They may be treated as an informal group, as distinct from "fish eagles" (or "sea eagles"), "snake eagles", and "giant forest eagles". [note 1] They may also be treated as a formal taxon, either as a tribe (Aquililae)[ citation needed ] or subfamily (Aquilinae).

The booted eagles, sea eagles, harpy eagles and buteonine hawks are heavily built birds that have traditionally been classified together in the large subfamily Buteoninae. In 2005, Heather Lerner and David Mindell [2] proposed separating the eagles into their own subfamilies Aquilinae, Haliaeetinae, and Harpiinae, leaving only the buteo–buteogallus clade in a more restricted Buteoninae.

Included in the booted eagles are the genera Aquila, Hieraaetus and Clanga; all species described as "hawk eagles" including the genera Spizaetus and Nisaetus ; as well as assorted monotypical genera such as Oroaetus , Lophaetus , Stephanoaetus , Polemaetus , Lophotriorchis and Ictinaetus .

Hawk eagles

Aquila eagles

The genus Aquila is distributed across every continent but for South America and Antarctica. Up to 20 species have been classified in the genus but the taxonomic placement of some of the traditionally included species has recently been questioned. Traditionally, the Aquila eagles have been grouped superficially as largish, mainly brownish or dark-colored booted eagles that vary little in transition from their juvenile to their adult plumages.

Genetic research has recently indicated a clade containing the near-circumpolar golden eagle (Aquila chrysaetos), Verreaux's eagle (A. verreauxii) of Africa, Asian Gurney's eagle (A. gurneyi) and the Australian wedge-tailed eagle (A. audax). This identification of this particular clade has long been suspected based on similar morphological characteristics amongst these large-bodied species. [3]

More surprisingly, the smaller, much paler-bellied species pair Bonelli's eagle (A. fasciatus) and African hawk-eagle (A. spilogaster), previously included in the genus Hieraaetus, have been revealed to be genetically much closer to the Verreaux's and golden eagle lineage than to other species traditionally included in the genus Aquila. [4] [5] [2]

Other largish Aquila species, the eastern imperial eagle (A. heliaca), the Spanish imperial eagle (A. adaberti), the tawny eagle (A. rapax) and the steppe eagles (A. nipalensis), are now thought to be separate, close-knit clade, which attained some similar characteristics to the golden eagle clade via convergent evolution. [5] [2]

Spotted eagles

Genetically, the "spotted eagles" ( A. pomarina, A. hasata & A. clanga ), have been discovered to be more closely related to the long-crested eagle (Lophaetus occipitalis) and the black eagle (Ictinaetus malaiensis), and many generic reassignments have been advocated. [5] [6] Some authorities[ who? ] place the spotted eagles in a separate genus, Clanga .

Hieraaetus

The genus Hieraaetus , including the booted eagle (H. pennatus), little eagle (H. morphnoides) and Ayres's hawk-eagle (H. ayresii), consists of much smaller species, that are in fact the smallest birds called eagles outside of the unrelated Spilornis serpent-eagle genus. This genus has recently been eliminated by some authorities and its members included in Aquila, although not all ornithological unions have followed this suit in this re-classification. [4] [2] [7] The small-bodied Wahlberg's eagle (H. wahlbergi) has been traditionally considered an Aquila species due to its lack of change from juvenile to adult plumage and brownish color, but it is genetically aligned to the Hieraaetus lineage. [5] [8] Cassin's hawk-eagle (H. africanus) is also probably closely related to the Hieraaetus group rather than the Spizaetus/Nisaetus "hawk-eagle" group (in which it was previously classified) which is not known to have radiated to Africa. [9]

Notes

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

Related Research Articles

<span class="mw-page-title-main">Eagle</span> Large carnivore bird

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. Outside this area, just 14 species can be found—two in North America, nine in Central and South America, and three in Australia.

<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">Golden eagle</span> Species of eagle

The golden eagle is a bird of prey living in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. They are one of the best-known birds of prey in the Northern Hemisphere. These birds are dark brown, with lighter golden-brown plumage on their napes. Immature eagles of this species typically have white on the tail and often have white markings on the wings. Golden eagles use their agility and speed combined with powerful feet and large, sharp talons to hunt a variety of prey, mainly hares, rabbits, and marmots and other ground squirrels. Golden eagles maintain home ranges or territories that may be as large as 200 km2 (77 sq mi). They build large nests in cliffs and other high places to which they may return for several breeding years. Most breeding activities take place in the spring; they are monogamous and may remain together for several years or possibly for life. Females lay up to four eggs, and then incubate them for six weeks. Typically, one or two young survive to fledge in about three months. These juvenile golden eagles usually attain full independence in the fall, after which they wander widely until establishing a territory for themselves in four to five years.

<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">African hawk-eagle</span> Species of bird

The African hawk-eagle is a large bird of prey. Like all eagles, it belongs to the family Accipitridae. This species’ feathered legs mark it as a member of the Aquilinae subfamily. The African hawk-eagle breeds in tropical Sub-Saharan Africa. It is a bird of assorted woodland, including both savanna and hilly areas but the tend to occur in woodland that is typically dry. The species tends to be rare in areas where their preferred habitat type is absent. This species builds a stick nest of around 1 m (3.3 ft) across in a large tree. The clutch is generally one or two eggs. The African hawk-eagle is powerfully built and hunts small to medium sized mammals and birds predominantly, occasionally taking reptiles and other prey as well. The call is a shrill kluu-kluu-kluu. The African hawk-eagle is considered a fairly stable species and a species of Least Concern per the IUCN.

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

Wahlberg's eagle is a bird of prey that is native to sub-Saharan Africa, where it is a seasonal migrant in the woodlands and savannas. It is named after the Swedish naturalist Johan August Wahlberg. Like all eagles, it belongs to the family Accipitridae.

<span class="mw-page-title-main">Changeable hawk-eagle</span> Crested hawk-eagle (Nisaetus cirrhatus) from South and Southeast Asia

The changeable hawk-eagle(Nisaetus cirrhatus) or crested hawk-eagle is a large bird of prey species of the family Accipitridae. More informal or antiquated English common names include the marsh hawk-eagle or Indian crested hawk-eagle. It is a member of the subfamily Aquilinae, with signature feathers, absent in tropical raptors from outside this subfamily, covering the tarsus. It was formerly placed in the genus Spizaetus, but studies pointed to the group being paraphyletic resulting in the Old World members being placed in Nisaetus and separated from the New World species. It is a typical “hawk-eagle” in that it is an agile forest-dwelling predator and like many such eagles readily varies its prey selection between birds, mammals or reptiles as well as other vertebrates. Among the members of its genus, the changeable hawk-eagle stands out as the most widely distributed, adaptable and abundant species. Individuals show a wide range of variation in plumage from pale to dark, varying with moult and age giving rise to the name "changeable".

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

The mountain hawk-eagle or Hodgson's hawk-eagle, is a large bird of prey native to Asia. The latter name is in reference to the naturalist, Brian Houghton Hodgson, who described the species after collecting one himself in the Himalayas. A less widely recognized common English name is the feather-toed eagle. Like all eagles, it is in the family Accipitridae. Its feathered tarsus marks this species as a member of the subfamily Aquilinae. It is a confirmed breeding species in the northern part of the Indian subcontinent, from India, Nepal through Bangladesh to Thailand, Taiwan, Vietnam and Japan, although its distribution could be wider still as breeding species. Like other Asian hawk-eagles, this species was earlier treated under the genera of Spizaetus but genetic studies have shown this group to be paraphyletic, resulting in the Old World members being placed in Nisaetus and separated from the New World species. As is typical of hawk-eagles, the mountain hawk-eagle is a forest dwelling opportunistic predator who readily varies its prey selection between birds, mammals and reptiles along with other vertebrates. Although classified currently as a least-concern species due its persistence over a rather wide distribution, this species is often quite rare and scarce and seems to be decreasing, especially in response to large-scale habitat degradation and deforestation.

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

The rufous-bellied eagle or rufous-bellied hawk-eagle is a bird of prey in the family Accipitridae that is found in the forested regions of tropical Asia. Relatively small for eagles and contrastingly patterned like a falcon, this species was earlier placed in the genus Hieraaetus and sometimes also in the genus Aquila but thought to be distinctive enough to belong to a separate genus.

<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.

<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.

<span class="mw-page-title-main">Little eagle</span> One of the closest living relatives of the Haasts eagle, along with the booted eagle

The little eagle is a very small eagle endemic to Australia.

<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">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">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.

<i>Nisaetus</i> Genus of birds

Nisaetus is a genus of subfamily Aquilinae found mainly in tropical Asia. They were earlier placed within the genus Spizaetus but molecular studies show that the Old World representatives were closer to the genus Ictinaetus than to the New World Spizaetus. They are slender-bodied, medium-sized hawk-eagles with rounded wings, long feathered legs, barred wings, crests and usually adapted to forest habitats.

<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.

References

  1. Stalcup, Carolyn. "All About Eagles". The American Eagle Foundation. Archived from the original on 2014-07-14. Retrieved 25 May 2014.
  2. 1 2 3 4 Lerner, Heather R.L.; Mindell, David P. (2005). "Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA" (PDF). Molecular Phylogenetics and Evolution. 37 (2): 327–346. doi:10.1016/j.ympev.2005.04.010. PMID   15925523 . Retrieved 2013-04-22.
  3. Eagles, Hawks and Falcons of the World by Leslie Brown & Dean Amadon. The Wellfleet Press (1986), ISBN   978-1555214722.
  4. 1 2 Watson, Jeff (2010). The Golden Eagle. A&C Black. ISBN   978-1-4081-1420-9.
  5. 1 2 3 4 Helbig, A.J., Kocum, A., Seibold, I. & Braun, M.J. (2005). "A multi-gene phylogeny of aquiline eagles (Aves: Accipitriformes) reveals extensive paraphyly at the genus level" (PDF). Molecular Phylogenetics and Evolution. Elseveir. 35 (1): 147–164. doi:10.1016/j.ympev.2004.10.003. PMID   15737588. Archived from the original (PDF) on 2012-08-13. Retrieved 2013-04-23.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. "Lophaetus pomarinus". The Peregrine Fund. Retrieved 2013-04-22.
  7. "Aquila morphnoides". The Peregrine Fund. Archived from the original on 2012-10-28. Retrieved 2013-04-22.
  8. "Aquila wahlbergi". The Peregrine Fund. Retrieved 2013-04-23.
  9. "Aquila africana". The Peregrine Fund. Archived from the original on 2012-10-26. Retrieved 2013-04-23.