Congo serpent eagle
Congo serpent eagle | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Accipitriformes |
Family: | Accipitridae |
Subfamily: | Circaetinae |
Genus: | Dryotriorchis Shelley, 1874 |
Species: | D. spectabilis
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Binomial name | |
Dryotriorchis spectabilis (Schlegel, 1863)
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Subspecies[2] | |
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The distribution of the Congo serpent eagle (orange) | |
Synonyms | |
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The Congo serpent eagle (Dryotriorchis spectabilis) is a species of
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
Taxonomy
The Congo serpent eagle was first described in 1863 by
Despite Shelley's reclassification, the species was later merged into the genus Circaetus in 2005, along with other taxa popularly known as "serpent eagles". However, a 2018 study recovered this classification as being paraphyletic with respect to Terathopius, and for this reason, reclassified it back into Dryotriorchis. This was followed by the International Ornithological Congress in 2022.[9]
The Congo serpent eagle is superficially similar in plumage and size to Cassin's hawk-eagle, which has an overlapping range with the serpent eagle.[10] It has been suggested that the Congo serpent eagle evolved to mimic 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 by birds through its resemblance to a predator of birds.[10] D. s. spectabilis more closely resembles the immature Cassin's hawk-eagle, while D. s. batesi resembles the adult.[10] This is one of very few suspected examples of avian mimicry.[10]
Description
This hawk is a medium-sized, slender species with short, rounded wings and a long, rounded tail.[3] It is 54 to 60 centimeters (21 to 24 in) long, with the tail contributing 24.5 to 26.8 centimeters (9.6 to 10.6 in).[10] The wingspan is 94 to 106 centimeters (37 to 42 in) across.[10] 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.[3] The feathers on the top of the head are slightly pointed, giving this species a hint of a crest.[10] The remaining upperparts are a dark chocolate brown.[3] The cheeks are light brown while the throat is buffy white with streaks.[3] The eyes are large and dark brown or grey in females and yellow in males while the beak is short but deep.[11][12] It also has a black median streak.[3] The bird's underparts are white with variable amounts of rufous wash and a number of large, round blackish spots.[3] The serpent eagle's thighs are barred sepia-brown and white, while the undertail is white.[3] The underwing is largely white with some black spots and brown coloration.[3] The tail is light brown, with five to six broad black bars.[7] The claws are short and sharp, while the legs are yellow.[3] Sexes are similar, though the female averages about three percent larger than the male.[12] Immatures have a white crown and mantle, while the upper back has rounded brown or black spots that vanish as the bird ages.[3] The wings and tail are greyish-brown and paler than those of the adults and are more darkly barred.[3]
D. s. batesi is similar to the nominate subspecies, but is browner and paler on the back while the spots on D. s. spectabilis's chest only appear on this subspecies' flanks.[3] The immature does possess a spotted chest, with the spots vanishing as the bird ages.[6]
This is a very vocal raptor and is one of the most frequently heard birds of prey in its range.[13] It makes a cat-like meowing sound as well as a low, mournful, nasal "cow-cow-cow" at intervals over extended periods of time.[12][13] When heard over a large distance, some ornithologists have compared its call to that of a turaco.[13]
Distribution and habitat
The Congo serpent eagle lives in southern Sierra Leone and Guinea, Liberia, and southern Côte d'Ivoire and Ghana.
Ecology and behavior
Little is known about this species' behavior.[16] The Congo serpent eagle lives in the understory of its habitat and occasionally perches on lower boughs in tall trees.[13] It lives either alone or in pairs.[12] This species is known to hunt snakes, lizards, especially chameleons, toads, and potentially small mammals.[8][13] 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.[12] Its large eyes enable this species to hunt in low light, though it is diurnal.[10][13] Studies on the species' eyes have shown that they have about two times the visual resolution of a human's.[17] It may breed from October to December in Gabon and from June to November in the Democratic Republic of the Congo.[12]
Relationship with humans
Currently, the Congo serpent eagle's population is dwindling due to deforestation.
References
- ^ BirdLife International (2012). "Dryotriorchis spectabilis". IUCN Red List of Threatened Species. 2012. Retrieved 26 November 2013.
- ^ Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.2). doi : 10.14344/IOC.ML.10.2.
- ^ a b c d e f g h i j k l m n o p q r Brown 1982, p. 350
- ^ a b c Shelley, George Ernest (1874). "Note on Dryotriorchis, a new Genus of Harrier Eagles from West Africa". The Ibis. IV (3): 90–91.
- ^ Beddard, F. E. (1903). "On the modifications of structure in the syrinx of the Accipitres, with remarks on other points in anatomy of that group". Proceedings of the Zoological Society of London. 1903: 157–163.
- ^ .
- ^ a b c Ferguson-Lees 2001, p. 128
- ^ a b Thiollay 1994, p. 134
- ^ "Hoatzin, New World vultures, Secretarybird, raptors – IOC World Bird List". Retrieved 2022-08-24.
- ^ hdl:10261/34063.
- ^ a b c d e Ferguson-Lees 2001, p. 471
- ^ a b c d e f g Ferguson-Lees 2001, p. 472
- ^ a b c d e f Brown 1982, p. 351
- ^ a b c "Species factsheet: Dryotriorchis spectabilis". BirdLife International. 2011. Archived from the original on 2015-10-07. Retrieved 2011-11-08.
- ^ a b "Congo Serpent Eagle (Dryotriorchis spectabilis)". BirdLife International. 2011. Archived from the original on 2015-11-17. Retrieved 2011-11-08.
- ^ Demey, Ron; William Ossom (2007). "Rapid survey of the birds of the Atewa Range Forest Reserve, Ghana" (PDF). RAP Bulletin of Biological Assessment. 85: 61.
- ^ S2CID 8034443.
- ^ Scharning, Kjell. "Congo Serpent Eagle Stamps". Theme Birds on Stamps. Retrieved 2011-11-15.
Cited texts
- Brown, Leslie H.; Urban, Emil K.; Newman, Kenneth (1982). The Birds of Africa Volume I. London: Academic Press. ISBN 978-0-12-137301-6.
- Ferguson-Lees, James; David A. Christie (2001). Raptors of the World. Singapore: Houghton Mifflin. ISBN 978-0-618-12762-7.
- Thiollay, Jean-Marc (1994). "Family Accipitridae (Hawks and Eagles)". In del Hoyo, Josep; Elliott, Andrew; Sargatal, Jordi (eds.). ISBN 978-84-87334-15-3.