Hieraaetus
Encyclopedia
The genus
Hieraaetus, sometimes known as hawk-eagles, denoted a group of smallish eagle
s usually placed in the Buteoninae
subfamily of accipitrid
s.
At present, 3 species
of medium-sized birds of prey inhabiting Africa
and New Guinea
are retained in this group. These are:
The Booted Eagle
(formerly Hieraaetus pennatus), Bonelli's Eagle
(formerly H. fasciatus), the Little Eagle
(formerly H. morphnoides) and the Rufous-bellied Eagle
(formerly H. kienerii) have been determined by recent genetic
research to be polyphyletic and clustered along with the eagles of the genus Aquila
rather than to their traditional group.
This creates a taxonomic problem: The Booted Eagle is the type species
of Hieraaetus, making that name a junior synonym of Aquila. Consequently, should any hawk-eagles be retained as a distinct group, they need to get a different genus name.
Sometimes the entire genus is merged into Aquila. That the remaining 3 species are probably still not a monophyletic group is apparent by their biogeography
, which would quite implausibly require that a number of relatives living between Africa and New Guinea had become extinct prehistorically without leaving any trace or descendants.
Christidis and Boles (2008) use an alternative approach. Accepting that both Aquila and Hieraaetus are polyphyletic, they move spilogaster and fasciatus with the Aquila genus and retain the other former Hieraaetus group along with morphnoides and Aquila wahlbergi within the new delimitation of Hieraaetus.
Whether the fossil
"Hieraaetus" edwardsi (Middle -? Late Miocene of SW Europe) belongs to the hawk-eagles proper (if there is such a thing) or into Aquila has not been determined.
Hieraaetus kienerii was found to be distinct and may well need to be assigned to a new genus.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Hieraaetus, sometimes known as hawk-eagles, denoted a group of smallish eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
s usually placed in the Buteoninae
Buteoninae
Buteoninae is a bird of prey subfamily which consists of medium to large broad-winged species.They have large powerful hooked beaks for tearing flesh from their prey, strong legs and powerful talons...
subfamily of accipitrid
Accipitridae
The Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds 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...
s.
At present, 3 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of medium-sized birds of prey inhabiting Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
are retained in this group. These are:
- African Hawk-Eagle, "Hieraaetus" spilogaster
- Little EagleLittle EagleThe Little Eagle is a very small eagle native to Australasia, measuring 45–55 cm in length and weighing 815 g – roughly the size of a Peregrine Falcon. It tends to inhabit open woodland, grassland and arid regions, shunning dense forest...
, "Hieraaetus" morphnoides- Pygmy Eagle, "Hieraaetus" morphnoides weiskei
- Ayres's Hawk-EagleAyres's Hawk-eagleAyres's Hawk-Eagle is a species of bird of prey in the Accipitridae family. It is found throughout Sub-Saharan Africa. Its name honours South African ornithologist Thomas Ayres.-References:...
, "Hieraaetus" ayresii
The Booted Eagle
Booted Eagle
The Booted Eagle is a medium-sized bird of prey. It is about in length and has a wingspan of . Like all eagles, it belongs to the family Accipitridae....
(formerly Hieraaetus pennatus), Bonelli's Eagle
Bonelli's Eagle
The Bonelli's Eagle is a large bird of prey. Like all eagles, it belongs to the family Accipitridae.It breeds in southern Europe, Africa both north and south of the Sahara Desert and across southern Asia to Indonesia...
(formerly H. fasciatus), the Little Eagle
Little Eagle
The Little Eagle is a very small eagle native to Australasia, measuring 45–55 cm in length and weighing 815 g – roughly the size of a Peregrine Falcon. It tends to inhabit open woodland, grassland and arid regions, shunning dense forest...
(formerly H. morphnoides) and the Rufous-bellied Eagle
Rufous-bellied Eagle
The Rufous-bellied Hawk-Eagle is a bird of prey in the family Accipitridae, which also includes the buzzards, hawks and Old World vultures. It was earlier placed under the genus Hieraaetus but this eagle may well belong to a separate genus. The name of Kienastur had been suggested.Rufous-bellied...
(formerly H. kienerii) have been determined by recent genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
research to be polyphyletic and clustered along with the eagles of the genus Aquila
Aquila (genus)
Aquila is the genus of true eagles. It is often united with the buteos, sea eagles and other more heavyset Accipitridae, but more recently it appears as if they are less distinct from the more slender accipitrine hawks than believed...
rather than to their traditional group.
This creates a taxonomic problem: The Booted Eagle is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of Hieraaetus, making that name a junior synonym of Aquila. Consequently, should any hawk-eagles be retained as a distinct group, they need to get a different genus name.
Sometimes the entire genus is merged into Aquila. That the remaining 3 species are probably still not a monophyletic group is apparent by their biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
, which would quite implausibly require that a number of relatives living between Africa and New Guinea had become extinct prehistorically without leaving any trace or descendants.
Christidis and Boles (2008) use an alternative approach. Accepting that both Aquila and Hieraaetus are polyphyletic, they move spilogaster and fasciatus with the Aquila genus and retain the other former Hieraaetus group along with morphnoides and Aquila wahlbergi within the new delimitation of Hieraaetus.
Whether the fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
"Hieraaetus" edwardsi (Middle -? Late Miocene of SW Europe) belongs to the hawk-eagles proper (if there is such a thing) or into Aquila has not been determined.
Hieraaetus kienerii was found to be distinct and may well need to be assigned to a new genus.