The Congo serpent eagle (''Dryotriorchis spectabilis'') is a species of
bird of prey
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators h ...
in the family
Accipitridae
The Accipitridae is one of the three families within the order Accipitriformes, and is 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-s ...
. It is the only member of the
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Dryotriorchis'', although it was formerly placed in ''
Circaetus
''Circaetus'', the snake eagles, is a genus of medium-sized eagles in the bird of prey family Accipitridae. They are mainly resident African species, but the migratory short-toed snake eagle breeds from the Mediterranean basin into Russia, the ...
''. This species is distributed across the
African tropical rainforest, including
upper and
lower Guinean forests The Lower Guinean forests is region of coastal tropical moist broadleaf forest in West Africa, extending along the eastern coast of the Gulf of Guinea from eastern Benin through Nigeria and Cameroon.
The Dahomey Gap, a region of savanna and dry for ...
. This serpent eagle specializes in hunting in these forests’ dark understories. It has two subspecies, the
nominate subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
''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
Cassin's hawk-eagle (''Aquila africana'') 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 ...
, and some ornithologists believe that this likeness is a rare example of avian
mimicry
In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. Often, mimicry f ...
. It is a very vocal raptor, and often is one of the most heard species in its habitat.
This serpent eagle feeds on snakes, chameleons, and toads, and hunts these species by dropping onto them from a perch in the understory. Its excellent eyesight enables it to hunt in the dark forest. Very little is known about its breeding habits, though it is suspected to breed from June to December. The Congo serpent eagle is listed as a species of
Least Concern
A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...
due to its large range and population. This species has been kept as a pet.
Taxonomy
The Congo serpent eagle was first described in 1863 by
Hermann Schlegel
Hermann Schlegel (10 June 1804 – 17 January 1884) was a German ornithologist, herpetologist and ichthyologist.
Early life and education
Schlegel was born at Altenburg, the son of a brassfounder. His father collected butterflies, which stimula ...
as ''Astur spectabilis'' from a specimen collected near
Elmina
Elmina, also known as Edina by the local Fante people, Fante, is a town and the capital of the Komenda/Edina/Eguafo/Abirem Municipal District, Komenda/Edina/Eguafo/Abirem District on the south coast of Ghana in the Central Region, Ghana, Centra ...
, Ghana.
[Brown 1982, p. 350] Schlegel published his description in ''Nederlandsch Tijdschrift voor De Dierkunde'' and placed this species within the
goshawk
Goshawk may refer to several species of birds of prey, mainly in the genus ''Accipiter'':
* Northern goshawk, ''Accipiter gentilis'', often referred to simply as the goshawk, since it is the only goshawk found in much of its range (in Europe and N ...
s.
In 1874
George Ernest Shelley
Captain George Ernest Shelley (15 May 1840 – 29 November 1910) was an English geologist and ornithologist. He was a nephew of the poet Percy Bysshe Shelley.
Shelley was educated at the Lycée de Versailles and served a few years in the Grenad ...
, who had access to more specimens, realized that the species was not a goshawk and moved the species into its own
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
, ''Dryotriorchis''.
''Dryotriorchis'' is a distinct genus due to its short wings, long tail, short crest, and oval nostrils.
The word "Dryo-" is from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
for "oak" and "triorchis" from the Greek for "hawk", specifically a kind of hawk thought to have three testicles.
[ It is believed that the genus is more closely related to '']Circaetus
''Circaetus'', the snake eagles, is a genus of medium-sized eagles in the bird of prey family Accipitridae. They are mainly resident African species, but the migratory short-toed snake eagle breeds from the Mediterranean basin into Russia, the ...
'' than ''Terathopius
The bateleur (; ''Terathopius ecaudatus'') is a medium-sized eagle in the family Accipitridae. It is often considered a relative of the snake eagles and, like them, it is classified within the subfamily Circaetinae.Kemp, A. C., G. M. Kirwan, an ...
'', and it is possibly a link between these and the Asian genus ''Spilornis
''Spilornis'' is a genus of bird of prey in the family Accipitridae. As adults all have dark crowns, and bright yellow eyes and cere.Ferguson-Lees & Christie (2001). ''Raptors of the World.'' Christopher Helm, London. These medium-sized raptors ...
''. The syrinx
In classical Greek mythology, Syrinx (Greek Σύριγξ) was a nymph and a follower of Artemis, known for her chastity. Pursued by the amorous god Pan, she ran to a river's edge and asked for assistance from the river nymphs. In answer, sh ...
morphology is distinctly like those of accipiter hawks but shows similarities to features found in ''Nisaetus
''Nisaetus'' (Crested hawk-eagles group) 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 ge ...
''. Two subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
are known: the nominate subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
''Dryotriorchis spectabilis spectabilis'' and ''D. s. batesi''. ''D. s. batesi'' was originally described as a separate species, ''Dryotriorchis batesi'', by Richard Bowdler Sharpe
Richard Bowdler Sharpe (22 November 1847 – 25 December 1909) was an English zoologist and ornithologist who worked as curator of the bird collection at the British Museum of natural history. In the course of his career he published several mono ...
in 1904 due to its unspotted breast. Sharpe named the subspecies in honor of G. L. Bates, who shipped him specimens from Cameroon. This species is also known as the West African Serpent eagle and the African Serpent-eagle.[Ferguson-Lees 2001, p. 128][Thiollay 1994, p. 134]
Despite Shelley's reclassification, the species was later merged into the genus ''Circaetus
''Circaetus'', the snake eagles, is a genus of medium-sized eagles in the bird of prey family Accipitridae. They are mainly resident African species, but the migratory short-toed snake eagle breeds from the Mediterranean basin into Russia, the ...
'' in 2005, along with other taxa popularly known as "serpent eagles". However, a 2018 study recovered this classification as being paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
with respect to ''Terathopius'', and for this reason, reclassified it back into ''Dryotriorchis''. This was followed by the International Ornithological Congress
International is an adjective (also used as a noun) meaning "between nations".
International may also refer to:
Music Albums
* ''International'' (Kevin Michael album), 2011
* ''International'' (New Order album), 2002
* ''International'' (The T ...
in 2022.
The Congo serpent eagle is superficially similar in plumage and size to Cassin's hawk-eagle
Cassin's hawk-eagle (''Aquila africana'') 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 ...
, which has an overlapping range with the serpent eagle. It has been suggested that the Congo serpent eagle evolved to mimic
MIMIC, known in capitalized form only, is a former simulation computer language developed 1964 by H. E. Petersen, F. J. Sansom and L. M. Warshawsky of Systems Engineering Group within the Air Force Materiel Command at the Wright-Patterson AFB in ...
the Cassin's hawk-eagle, which could give the serpent eagle several advantages, possibly including the ability to trick its reptilian prey into not fleeing, lowering its own predation, and/or minimizing mobbing
Mobbing, as a sociological term, means bullying of an individual by a group, in any context, such as a family, peer group, school, workplace, neighborhood, community, or online. When it occurs as physical and emotional abuse in the workplace, suc ...
by birds through its resemblance to a predator of birds. ''D. s. spectabilis'' more closely resembles the immature Cassin's hawk-eagle, while ''D. s. batesi'' resembles the adult. This is one of very few suspected examples of avian mimicry.
Description
This hawk is a medium-sized, slender species with short, rounded wings and a long, rounded tail. It is long, with the tail contributing . The wingspan is across. The adult of the nominate subspecies, ''Dryotriorchis spectabilis spectabilis'', has a blackish-brown crown and upper neck while the sides of the neck and a broad collar are a dark rufous-brown. The feathers on the top of the head are slightly pointed, giving this species a hint of a crest. The remaining upperparts are a dark chocolate brown. The cheeks are light brown while the throat is buffy white with streaks. The eyes are large and dark brown or grey in females and yellow in males while the beak
The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food ...
is short but deep. It also has a black median streak. The bird's underparts are white with variable amounts of rufous wash and a number of large, round blackish spots. The serpent eagle's thighs are barred sepia-brown and white, while the undertail is white. The underwing is largely white with some black spots and brown coloration. The tail is light brown, with five to six broad black bars. The claws are short and sharp, while the legs are yellow. Sexes are similar, though the female averages about three percent larger than the male.[Ferguson-Lees 2001, p. 472] Immatures have a white crown and mantle, while the upper back has rounded brown or black spots that vanish as the bird ages. The wings and tail are greyish-brown and paler than those of the adults and are more darkly barred.
''D. s. batesi'' is similar to the nominate subspecies, but is browner and paler on the back while the spots on ''D. s. spectabiliss chest only appear on this subspecies' flanks. The immature does possess a spotted chest, with the spots vanishing as the bird ages.
This is a very vocal raptor and is one of the most frequently heard birds of prey in its range.[Brown 1982, p. 351] It makes a cat-like meowing sound as well as a low, mournful, nasal "cow-cow-cow" at intervals over extended periods of time. When heard over a large distance, some ornithologists have compared its call to that of a turaco
The turacos make up the bird family Musophagidae ( "banana-eaters"), which includes plantain-eaters and go-away-birds. In southern Africa both turacos and go-away-birds are commonly known as loeries. They are semi-zygodactylous: the fourth ( ...
.
Distribution and habitat
The Congo serpent eagle lives in southern Sierra Leone and Guinea, Liberia, and southern Côte d'Ivoire and Ghana.[Ferguson-Lees 2001, p. 471] It is also found in southern Nigeria and the Central African Republic south through northern and eastern Democratic Republic of the Congo in the east and through Gabon into the northern Republic of the Congo in the west with an isolated population in northern Angola. ''D. s. spectabilis'' is found in upper Guinean forests from Liberia to northern Cameroon, while ''D. s. batesi'' is found in lower Guinean forests The Lower Guinean forests is region of coastal tropical moist broadleaf forest in West Africa, extending along the eastern coast of the Gulf of Guinea from eastern Benin through Nigeria and Cameroon.
The Dahomey Gap, a region of savanna and dry for ...
from southern Cameroon through Gabon and western Uganda. Its range covers . The species lives in dense primary forest below in elevation in the dark understory. As it is adapted for dense forest, it is not well-adapted for secondary forests and plantations. The Congo serpent eagle does not migrate, though it is unknown if it is locally nomadic.
Ecology and behavior
Little is known about this species' behavior. The Congo serpent eagle lives in the understory of its habitat and occasionally perches on lower boughs in tall trees. It lives either alone or in pairs. This species is known to hunt snakes, lizards, especially chameleon
Chameleons or chamaeleons (family Chamaeleonidae) are a distinctive and highly specialized clade of Old World lizards with 202 species described as of June 2015. The members of this family are best known for their distinct range of colors, bein ...
s, toads, and potentially small mammals. It hunts by dropping to the ground from its perch in the understory, where it may strike its prey repeatedly with its feet; this serpent eagle may also grab prey from the foliage while hunting. Its large eyes enable this species to hunt in low light, though it is diurnal. Studies on the species' eyes have shown that they have about two times the visual resolution of a human's. It may breed from October to December in Gabon and from June to November in the Democratic Republic of the Congo.
Relationship with humans
Currently, the Congo serpent eagle's population is dwindling due to deforestation. However, it is listed as a species of Least Concern
A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...
due to its large population of over 10,000 adults and large range of . This species has been kept as a pet and in the 1970s was available from some pet shops. The Congo serpent eagle has been depicted on postage stamps from the Democratic Republic of the Congo and Tanzania.
References
Cited texts
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External links
Picture, video, and distribution map
{{Taxonbar, from=Q1061063, from2=Q27074627
Congo serpent eagle
Birds of prey of Sub-Saharan Africa
Birds of the African tropical rainforest
Congo serpent eagle
Congo serpent eagle
Taxonomy articles created by Polbot