Crested Serpent Eagle
Encyclopedia
The Crested Serpent Eagle (Spilornis cheela) is a medium-sized bird of prey
that is found in forested habitats across tropical Asia. Within its widespread range, 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
(S. holospila), Andaman Serpent Eagle (S. elgini) and South Nicobar Serpent Eagle (S. klossi) 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
.
s are black with broad white bars. Young birds show a lot of white on the head. The tarsus is unfeathered and covered by hexagonal scales. The upper mandible does not have an overhanging festoon to the tip.
Within its widespread range across tropical Asia, 21 populations have been named as subspecies. The most widespread subspecies are the nominate from along the sub-Himalayan
range in India
and Nepal
, melanotis in Peninsular India, spilogaster of Sri Lanka
, burmanicus in most of Indochina
, ricketti in northern Vietnam
and southern China
, malayensis of the Thai-Malay Peninsula and northern Sumatra
, pallidus from northern Borneo
, richmondi from southern Borneo, bido from Java
and Bali
, batu from southern Sumatra and Batu
, hoya from Taiwan
, rutherfordi from Hainan
, and palawanensis from Palawan
. The remaining subspecies are all restricted to smaller islands: davisoni in the Andamans, minimus (Central Nicobar Serpent Eagle) from the central Nicobars, perplexus (Ryukyu Serpent Eagle) from Ryukyu, natunensis (Natuna Serpent Eagle) from Natuna, abbotti (Simeulie Serpent Eagle) from Simeulue
, sipora (Mentawai Serpent Eagle) from Mentawai, asturinus (Nias Serpent Eagle) from Nias
, and baweanus (Bawean Serpent Eagle) of the Bawean
. The last seven (with English names in brackets) are sometimes treated as separate species. Although the Crested Serpent Eagle remains widespread and fairly common overall, some of the taxa that are restricted to small islands are believed to have relatively small populations that likely are in the hundreds. The rarest is probably the Bawean Serpent Eagle with a declining population of about 26–37 pairs, which makes it critically endangered
.
The nominate subspecies has a black throat while the peninsular Indian form has a brownish throat. There are clinal latitudinal variations, with size decreasing southward. The small islands taxa are generally smaller in size than the taxa from the Asian mainland/larger islands in a phenomenon termed as insular dwarfism
.
The specific name cheela is derived from the Hindi name for kites.
The Crested Serpent Eagle, as its English
name suggests, is a specialist reptile
eater which hunts over forests, often close to wet grassland, for snake
s and lizard
s. It is placed along with the snake eagles of the genus Circaetus in the subfamily Circaetinae. It is found mainly over areas with thick vegetation both on the low hills and the plains. This species is a resident species, but in some parts of their range they are found only in summer.
The call is a distinctive Kluee-wip-wip with the first note being high and rising. They call a lot in the late mornings from their perches where they spend a lot of time and they rise on thermal
s in the mornings. When alarmed, they erect the crest and the head appears large and framed by the ruff. They will sometimes follow snakes on the ground. They roost in the interiors of trees with dense foliage. A radio-telemetric study of the species in Taiwan found that the birds spend 98% of the day perched and usually finding food in the morning hours. They appear to use a sit and wait foraging strategy.
The breeding season is mainly in winter to spring. The nest is a large platform built high on a tree. Both birds in a pair build the nest but the female alone incubates. In central India, the Terminalia tomentosa is often used. The nests are lined with green leaves from the tree on which it is placed. The usual clutch is one egg but two are sometimes laid and only a single chick is successfully raised in a season. Nests are defended by the parents.
Several species of endoparasitic nematodes have been recovered from the intestines of Crested Serpent Eagles including Madelinema angelae Avian pox virus infections which cause warts on the face have been observed in a wild bird living in Taiwan. A number of ectoparasitic bird lice have been described from the species including Kurodaia cheelae.
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
that is found in forested habitats across tropical Asia. Within its widespread range, there are considerable variations and some authorities prefer to treat several of its subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
as completely separate species. In the past, several species including the Philippine Serpent Eagle
Philippine Serpent Eagle
The Philippine Serpent Eagle, Spilornis holospilus, is an eagle found in the major islands of the Philippines. It is sometimes treated as a race of the Crested Serpent Eagle . This species is usually found in forest clearings, open woodlands, and sometimes in cultivated lands with scattered...
(S. holospila), Andaman Serpent Eagle (S. elgini) and South Nicobar Serpent Eagle (S. klossi) were treated as subspecies of the Crested Serpent Eagle. All members within the species complex
Species complex
A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of 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
Circaetus
Circaetus, the snake eagles, is a genus of medium-sized eagles in the bird of prey family Accipitridae which also includes many other diurnal raptors such as buzzards and harriers....
snake-eagles in the subfamily Circaetinae
Circaetinae
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 named as "snake-eagles" or "serpent-eagles". The only exception is the Bateleur,...
.
Description
This medium-large, dark brown eagle is stocky, with rounded wings and a short tail. Its short black and white fan-shaped nuchal crest gives it a thick-necked appearance. The bare facial skin and feet are yellow. The underside is spotted with white and yellowish-brown. When perched the wing tips do not reach until the tail tip. In soaring flight, the broad and paddle-shaped wings are held in a shallow V. The tail and underside of the flight featherFeather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
s are black with broad white bars. Young birds show a lot of white on the head. The tarsus is unfeathered and covered by hexagonal scales. The upper mandible does not have an overhanging festoon to the tip.
Distribution, taxonomy and status
Himalayan
Himalayan can refer to:* The Himalayas mountain range* Himalayan , the type of cat* List of rabbit breeds#Himalayan, the breed of rabbit* The Himalayans, a band...
range in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
, melanotis in Peninsular India, spilogaster of Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
, burmanicus in most of Indochina
Indochina
The Indochinese peninsula, is a region in Southeast Asia. It lies roughly southwest of China, and east of India. The name has its origins in the French, Indochine, as a combination of the names of "China" and "India", and was adopted when French colonizers in Vietnam began expanding their territory...
, ricketti in northern Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
and southern China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, malayensis of the Thai-Malay Peninsula and northern Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
, pallidus from northern Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
, richmondi from southern Borneo, bido from Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
and Bali
Bali
Bali is an Indonesian island located in the westernmost end of the Lesser Sunda Islands, lying between Java to the west and Lombok to the east...
, batu from southern Sumatra and Batu
Batu Islands
The Batu Islands are an archipelago of Indonesia located in the Indian Ocean off the west coast of Sumatra, between Nias and Siberut. The three primary islands, of approximately equal size, are Pini, Tanahmasa, and Tanahbala. There are forty-eight smaller islands, of which less than half are...
, hoya from Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, rutherfordi from Hainan
Hainan
Hainan is the smallest province of the People's Republic of China . Although the province comprises some two hundred islands scattered among three archipelagos off the southern coast, of its land mass is Hainan Island , from which the province takes its name...
, and palawanensis from Palawan
Palawan
Palawan is an island province of the Philippines located in the MIMAROPA region or Region 4. Its capital is Puerto Princesa City, and it is the largest province in the country in terms of total area of jurisdiction. The islands of Palawan stretch from Mindoro in the northeast to Borneo in the...
. The remaining subspecies are all restricted to smaller islands: davisoni in the Andamans, minimus (Central Nicobar Serpent Eagle) from the central Nicobars, perplexus (Ryukyu Serpent Eagle) from Ryukyu, natunensis (Natuna Serpent Eagle) from Natuna, abbotti (Simeulie Serpent Eagle) from Simeulue
Simeulue
Simeulue Regency is a regency in the Aceh province of Indonesia. It occupies the whole island of Simeulue , 150 km off the west coast of Sumatra, with a population of 80,279 ....
, sipora (Mentawai Serpent Eagle) from Mentawai, asturinus (Nias Serpent Eagle) from Nias
Nias
Nīas is an island off the western coast of Sumatra, Indonesia. Nias is also the name of the archipelago, containing the Hinako archipelago....
, and baweanus (Bawean Serpent Eagle) of the Bawean
Bawean
Bawean is an island of Indonesia located approximately 150 km north of Surabaya in the Java Sea, off the coast of Java. It is administered by Gresik Regency of East Java province. It is approximately 15 km in diameter and is circumnavigated by a single narrow road. Bawean is dominated by...
. The last seven (with English names in brackets) are sometimes treated as separate species. Although the Crested Serpent Eagle remains widespread and fairly common overall, some of the taxa that are restricted to small islands are believed to have relatively small populations that likely are in the hundreds. The rarest is probably the Bawean Serpent Eagle with a declining population of about 26–37 pairs, which makes it critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
.
The nominate subspecies has a black throat while the peninsular Indian form has a brownish throat. There are clinal latitudinal variations, with size decreasing southward. The small islands taxa are generally smaller in size than the taxa from the Asian mainland/larger islands in a phenomenon termed as insular dwarfism
Insular dwarfism
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of the reduction in size of large animals – typically mammals – when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf...
.
The specific name cheela is derived from the Hindi name for kites.
Behaviour and ecology
The Crested Serpent Eagle, as its English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
name suggests, is a specialist reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
eater which hunts over forests, often close to wet grassland, for snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s and lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s. It is placed along with the snake eagles of the genus Circaetus in the subfamily Circaetinae. It is found mainly over areas with thick vegetation both on the low hills and the plains. This species is a resident species, but in some parts of their range they are found only in summer.
The call is a distinctive Kluee-wip-wip with the first note being high and rising. They call a lot in the late mornings from their perches where they spend a lot of time and they rise on thermal
Thermal
A thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection. The sun warms the ground, which in turn warms the air directly above it...
s in the mornings. When alarmed, they erect the crest and the head appears large and framed by the ruff. They will sometimes follow snakes on the ground. They roost in the interiors of trees with dense foliage. A radio-telemetric study of the species in Taiwan found that the birds spend 98% of the day perched and usually finding food in the morning hours. They appear to use a sit and wait foraging strategy.
The breeding season is mainly in winter to spring. The nest is a large platform built high on a tree. Both birds in a pair build the nest but the female alone incubates. In central India, the Terminalia tomentosa is often used. The nests are lined with green leaves from the tree on which it is placed. The usual clutch is one egg but two are sometimes laid and only a single chick is successfully raised in a season. Nests are defended by the parents.
Several species of endoparasitic nematodes have been recovered from the intestines of Crested Serpent Eagles including Madelinema angelae Avian pox virus infections which cause warts on the face have been observed in a wild bird living in Taiwan. A number of ectoparasitic bird lice have been described from the species including Kurodaia cheelae.