Indian roller
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The Indian roller (Coracias benghalensis) is a bird of the family Coraciidae. It is Template:Cvt long with a wingspan of Template:Cvt and weighs Template:Cvt. The face and throat are pinkish, the head and back are brown, with blue on the rump and contrasting light and dark blue on the wings and tail. The bright blue markings on the wing are prominent in flight. The sexes are similar in appearance. Two subspecies are recognised.
The Indian roller occurs widely from West Asia to the Indian subcontinent. Often found perched on roadside trees and wires, it is common in open grassland and scrub forest habitats, and has adapted well to human-modified landscapes. It mainly feeds on insects, especially beetles. The species is best known for the aerobatic displays of males during the breeding season. Adult males and females form pair bonds and raise the young together. The female lays 3–5 eggs in a cavity or crevice, which is lined with a thin mat of straw or feathers. The roller is the state bird of three Indian states. It is listed as a species of least concern on the IUCN Red List.
TaxonomyEdit
The Indian roller was one of the many bird species originally described by Carl Linnaeus in the 1758 10th edition of Systema Naturae, where he coined the binomial name Corvus benghalensis.<ref>Template:Cite book</ref> Linnaeus based his description on the "Jay from Bengal" described and illustrated in 1731 by the English naturalist Eleazar Albin, derived from a drawing by illustrator Joseph Dandridge.<ref>Template:Cite book</ref>
In 1766, Linnaeus described an Indian roller under the name Coracias indica,<ref>Template:Cite book</ref> based on a description by George Edwards in 1764 of a specimen collected in Sri Lanka.<ref name=Edwards1764>Template:Cite book</ref> The latter name was used for many years; Indian ornithologist Biswamoy Biswas suspected it was because Linnaeus' 12th edition of Systema Naturae was preferred as the starting point for formal descriptions. German ornithologist Ernst Hartert determined there were distinct northern and southern subspecies and allocated benghalensis to the former and indicus to the latter. However, Biswas noted that the type locality (where the specimen was originally found) for benghalensis was Madras Presidency, which lies within the range of the southern subspecies, and proposed a neotype be selected from Bengal, where Linnaeus had assumed the taxon had come from.<ref>Template:Cite journal</ref> This was accepted by the International Commission on Zoological Nomenclature in 1962.<ref>Template:Cite journal</ref>
Two subspecies are recognized:<ref name=ioc>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
- C. b. benghalensis Template:Small occurs from western Asia to India north of the Vindhya Range.<ref name=pcr/>
- C. b. indicus Template:Small occurs in central and southern India and in Sri Lanka.<ref name=pcr/> It is distinguished by its slightly shorter wing and tail, darker blue crown and upper wing coverts, more brownish mantle and shoulder, and more pronounced red-brown collar on hindneck.<ref name=Cramp1985/>
The Indochinese roller (C. affinis) was often treated as a subspecies due to some hybridisation between the two taxa over an area from central Nepal to western Assam.<ref name=pcr/> However, a 2018 molecular study of nuclear and mitochondrial DNA showed that the latter taxon was actually most closely related to the purple-winged roller (C. temminckii) while the Indian roller was their next closest relative, diverging from a lineage that gave rise to those two species.<ref name=johansson18>Template:Cite journal</ref>
Template:Phylogeny/Coracias The International Ornithologists' Union has designated "Indian roller" the official common name for the species.<ref name=ioc/> In British India, it was also colloquially termed 'blue jay'.<ref name=thurston12/> The Indian roller is called 'Little King' by villagers in Khuzestan Province in Iran.<ref name=":1" />
DescriptionEdit
The Indian roller is a bulky and broad-winged bird with a large head and short neck and legs.<ref name=Cramp1985/><ref name=Fry1992>Template:Cite book</ref> It has a body length of Template:Cvt with a wingspan of Template:Cvt and weighs Template:Cvt.<ref name=Cramp1985>Template:Cite book</ref><ref name=handbook>Template:Cite book</ref> The bare skin around the eyes is dull orange, the legs and feet are yellow-brown. The bill is tinged with brown at the base. The iris is grey-brown.<ref name=Cramp1985/>
PlumageEdit
The plumage on the forehead, chin and lores are pinkish buff, the ear coverts are darker red-brown with pale cream or pinkish streaks, while the throat is a dull wine-red with narrow cream streaks. The crown and nape are a darker dull turquoise. The back and rump are a bright turquoise, and the belly is pale blue. The tail coverts are dark purple-blue with turquoise tips. The middle two tail feathers are greyish blue-olive with black shafts, while the surrounding tail feathers are an intense purple-blue with a broad pale blue band and greenish tinge towards the tips. The flight feathers on the wings have the same purple-blue colour of those on the tail, with a similar pale blue band across the most distal five or six primaries. The underwing coverts and Template:Birdgloss are pale blue, while the upperwing coverts are a dull green-blue. The primary coverts are pale blue with olive or purple-blue tips, and the lesser coverts are purple-blue along the leading edge of the wing.<ref name=Cramp1985/><ref name=Fry1992/><ref name=handbook/> The colours look dull when the bird is perched but become vibrant in flight.<ref name=Fry1992/> Moulting commences anywhere from mid-June to mid-August and concludes between November and the beginning of March.<ref name=Cramp1985/>
The blue colours of the flight feathers are structural and are formed by microstructures in the barbs that produce blue through scattering, which C.V. Raman noted in the 1930s as being more complex than can be explained by the Tyndall effect.<ref>Template:Cite journal</ref> Studies in 2010 found the feather barbs structured like a channel with β-keratin rods Template:Cvt in diameter with airspaces between them.<ref>Template:Cite journal</ref>
Adult males and females are similar in appearance and there are no seasonal changes.<ref name=Cramp1985/> Juvenile birds are duller, paler and browner in colour,<ref name=pcr>Template:Cite book</ref> with a dull green crown and dull green-blue belly tinged with buff. The bill is brown with a yellowish base rather than black.<ref name=Cramp1985/>
VoiceEdit
The Indian roller has a monosyllabic contact call which varies from a short chack to a longer, harsher tschow. Kaarsch calls are made during rolling displays, and increase in frequency and volume as the bird flies towards an intruder. When perched side by side, rollers make staccato chattering. In the nest, young produce a loud, "distressing" sound when calling for food, while young fledglings make a loud "screaming gobble" after eating. Newly independent rollers make cat-like mews while foraging.<ref name=Fry1992/>
Differences from other speciesEdit
At a distance the species can be mistaken for the European roller,<ref name=Cramp1985/> which is a migrant through parts of the Indian roller's range. The European roller has a longer neck and tail in flight, as well as black primaries and an all-blue head.<ref name=Fry1992/> The Indochinese roller is darker, larger and has a purplish brown and unstreaked face and breast,<ref name=pcr/> and blue-green forehead.<ref name=Fry1992/> The underwing coverts are a deeper shade of blue.<ref name=hbk>Template:Cite book</ref> Its call is higher-pitched and has a more nasal sound.<ref name=pcr/>
Distribution and habitatEdit
The Indian roller is distributed from Iraq and United Arab Emirates through the Indian subcontinent, including Sri Lanka.<ref name=iucn /> In Pakistan, it is resident in the wetlands around Chotiari Dam in Sindh, in Jiwani Coastal Wetland in Balochistan, and in Punjab along the Taunsa Barrage and Chenab River.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> It has been recorded as a summer visitor to Jalalabad in northeastern Afghanistan.<ref name="pcr" /> It has been recorded as a vagrant in Syria,Saudi Arabia, Masirah Island,<ref name="Fry1992" /> Qatar, Yemen, Socotra,<ref name="Middle East">Template:Cite book</ref> Bahrain, where it was sighted in 1996 and in 2008,<ref>Template:Cite journal</ref> Lakshadweep islands, the Maldive Islands,<ref name="pcr" /> and Turkey.<ref name="Middle East" /> In Kuwait, it is a common winter visitor at Green Island and farmlands near Al Jahra.<ref>Template:Cite journal</ref> In the 1970s, it was reported as a common winter visitor to the marshes and mudflats of Shadegan County in Iran.<ref>Template:Cite report</ref> However, it is listed as resident in Iran.<ref>Template:Cite journal</ref><ref name=Almasieh2020>Template:Cite journal</ref>
The species is common, and often found in open woodland dominated by trees of the genera Acacia and Prosopis, and has adapted well to human-modified landscapes such as parks and gardens, fields, date and coconut palm plantations. It has been nicknamed "roundabout bird" in northern Oman, where pairs live in vegetation at roundabouts.<ref name="Fry1992" /> In Oman, it is common in the Al Batinah Region and in cultivated areas east of the Sharqiya Sands below elevations of Template:Cvt.<ref>Template:Cite journal</ref> In India, it was sighted at elevations ranging from sea level in the Bhitarkanika Mangroves and the Gulf of Mannar to about Template:Cvt in the Nilgiri Mountains.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Behaviour and ecologyEdit
The Indian roller is generally not very gregarious and is usually found alone or in pairs.<ref name="Cramp1985" /> It is often territorial, though migrants may forage in flocks with no aggression. They patrol their territory by flying at treetop height or three-stories high and when an intruder is spotted, they drive it away by a fast rolling flight. Its migration patterns are not well understood; in Oman they are present year-round but appear to be more common in winter than summer.<ref name="Fry1992" />
The Indian roller spends a few minutes preening followed by flying around its roosting site. It favours electric or telegraph wires as perches. It has been observed perching in trees and shrubs at a height of Template:Convert from where it flies down to forage for ground insects. It also uses higher perches in the upper canopy of trees.<ref name=Sivakumaran>Template:Cite journal</ref> The display of the Indian roller is aerobatic with twists and turns.<ref name=pcr/> It is attracted by wildfires and darts into hot smoke in pursuit of insects.<ref name=Fry1992/> It has been observed following tractors for disturbed invertebrates. In agricultural habitats in southern India, it has been found at densities of about 50 birds per km2.<ref name=Sivakumaran/><ref name="Mathew, DN; Narendran, TC; Zacharias, VJ 1978 1178–1197">Template:Cite journal</ref><ref>Template:Cite journal</ref>
Nesting Indian rollers act aggressively towards potential predators. They drive away Indian jungle crows (Corvus culminatus) from nests and have even been recorded repeatedly divebombing an Egyptian vulture (Neophron percnopterus),<ref name="Cramp1985" /> and flying at humans.<ref name="Fry1992" />
Haemoproteus coraciae live inside the red-blood cells<ref>Template:Cite journal</ref> and Leucocytozoon blood parasites have been recorded in the lung tissues.<ref>Template:Cite journal</ref> Parasitic helminth worms Hadjelia srivastavai, Cyrnea graphophasiani,<ref>Template:Cite journal</ref> Habronema thapari<ref>Template:Cite journal</ref> and Synhimantus spiralis have been recorded from the gizzards of Indian rollers.<ref>Template:Cite journal</ref>
BreedingEdit
The breeding season is March to June, slightly earlier in southern India,<ref name=pcr/> when adult males and females form pair bonds.<ref name=Fry1992/> During courtship, mates perform aerial displays which include steep, undulating flights, somersaults, nose-drives, hovering and lateral rolling. This is accompanied by vocalizations.<ref name=Cramp1985/> The pair then perch and display to each other with bows, dropped wings and fanned tails and may engage in allopreening.<ref name=pcr/><ref name=Cramp1985/> The nest site is usually an existing hole in a tree, a dead palm or building but may also be a hole in a mud bank. The hole may be excavated completely in soft material such as rotten wood. A thin mat of feathers, straw or grass is placed at the bottom of the cavity.<ref name=Cramp1985/> In Bandhavgarh National Park, nests have been recorded at heights of Template:Cvt in Shorea robusta trees and Template:Cvt above the ground in Syzygium cumini trees.<ref>Template:Cite journal</ref>
The clutch consists of 3–5 eggs, which are white and oval with an average size of Template:Cvt. The eggs are incubated mainly by the female beginning as soon as the first egg is laid and hatch asynchronously after 17 to 19 days. The young are naked when first hatched and are fed and cared for by both parents. The fledging period lasts 30 to 35 days.<ref name=Cramp1985/>
Food and feedingEdit
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The Indian roller descends to the ground to capture insects and to a lesser extent amphibians, reptiles, birds, and small mammals.<ref name=Cramp1985/><ref>Template:Cite book</ref> It is attracted to swarms of winged termites; as many as 40 birds have been seen to perch on a Template:Cvt stretch of electric wire to hunt them.<ref>Template:Cite journal</ref> Beetles make up around 45% of its diet, followed by grasshoppers and crickets at around 25%.<ref name=Sivakumaran/>
The Indian roller often associates with the great Indian bustard (Ardeotis nigriceps), catching insects flushed out by the latter species.<ref>Template:Cite journal</ref> In Tamil Nadu, it was observed to forage mainly by gleaning (catching prey on a surface), followed by feeding on the ground and in the air.<ref>Template:Cite journal</ref> It occasionally dives into water to take frogs and fish, much like a kingfisher.<ref name=Fry1992/><ref name=hbk/> It may make use of opportunities such as insects attracted to lights, feeding even late after dusk.<ref>Template:Cite journal</ref>
In March 2019, an Indian roller was observed feeding on an Indian wolf snake (Lycodon aulicus) in Sathyamangalam Wildlife Sanctuary.<ref>Template:Cite journal</ref>
ConservationEdit
In India, the Indian roller received legal protection in 1887, when hunting it was banned under the Wild Birds Protection Act of 1887 and later under the Wild Birds and Animals Protection Act of 1912.<ref>Template:Cite journal</ref><ref>Template:Cite book</ref> In Iran, the Indian roller is protected by the Islamic code,<ref name=":1">Template:Cite journal</ref> but not listed as protected by law.<ref name=Almasieh2020/>
As of 2016, the Indian roller was listed as a species of least concern on the IUCN Red List, due to its wide range and apparent increasing population. The total population size is unknown, but it appears to be common in most of its range.<ref name=iucn/> As of 2015, about 2,500 breeding pairs were estimated to live in Iraq and 15,000 breeding pairs in the Arabian Peninsula; the population was thought to have increased in particular in the United Arab Emirates.<ref>Template:Cite book</ref>
ThreatsEdit
The numbers of Indian roller sighted along the highway between Aligarh and New Delhi decreased between the mid 1960s and mid 1980s, as traffic increased during that time.<ref>Template:Cite journal</ref> Its habit of feeding near roadsides sometimes results in collisions with traffic.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> Its habit of utilizing powerlines puts it at risk of electrocution. In Rajasthan, it was found to be the second most commonly electrocuted bird after the house crow (Corvus splendens).<ref>Template:Cite journal</ref>
In cultureEdit
The Indian roller is associated with Hindu legends and said to be sacred to Vishnu; it used to be caught and released during festivals such as Dussera or the last day of Durga Puja.<ref>Template:Cite book</ref> Adding its chopped feathers to fodder for cows was believed to increase the latter's milk yield, giving it the Telugu name of "paala-pitta" (Template:Langx), meaning 'milk bird'.<ref name=thurston12>Template:Cite book</ref> A Hindustani name is "neelkanth" (Template:Langx; Template:Langx),<ref>Template:Cite book</ref> meaning 'blue throat', a name associated with the deity Shiva due to a legend that he drank the Halahala poison emerging from Samudra Manthana to save the world but stopped it from going past his throat, turning it blue.<ref name=":0">Template:Cite journal</ref><ref>Template:Cite journal</ref>
The Kol people traditionally considered a sighting of an Indian roller as a good omen<ref>Template:Cite book</ref> as did people in Bengal who, upon seeing the bird, would chant a couplet showing devotion to Vishnu and seeking a vision of the bird at the time of their death.<ref name=":0" /> A nomadic tribe of fortune-tellers from the Vishakapatnam area wore feathers of the Indian roller on their head utilizing the folk belief that the bird could foretell events.<ref>Template:Cite book</ref> The Indian roller is the state bird of the Indian states of Odisha, Telangana,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and Karnataka.<ref>Template:Cite book</ref>
At the height of the plume trade in the early 20th century, the Indian roller was sought for export of its colourful feathers, and was among the most widely killed bird species in India.<ref>Template:Cite book</ref>
ReferencesEdit
External linksEdit
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