The Indian roller (Coracias benghalensis) is a bird of the family Coraciidae. It is 30–34 cm (12–13 in) long with a wingspan of 65–74 cm (26–29 in) and weighs 166–176 g (5.9–6.2 oz). 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.
The Indian roller is a bulky and broad-winged bird with a large head and short neck and legs. It has a body length of 30–34 cm (12–13 in) with a wingspan of 65–74 cm (26–29 in) and weighs 166–176 g (5.9–6.2 oz). 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.
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 axillary feathers 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. The colours look dull when the bird is perched but become vibrant in flight. Moulting commences anywhere from mid-June to mid-August and concludes between November and the beginning of March.
Scan of Indian roller feathers: a primary, two outer secondaries and two tail feathers
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. Studies in 2010 found the feather barbs structured like a channel with β-keratin rods 100 nm (3.9×10−6 in) in diameter with airspaces between them.
Adult males and females are similar in appearance and there are no seasonal changes. Juvenile birds are duller, paler and browner in colour, with a dull green crown and dull green-blue belly tinged with buff. The bill is brown with a yellowish base rather than black.
The Indian roller is distributed from Iraq and United Arab Emirates through the Indian subcontinent, including Sri Lanka. 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. It has been recorded as a summer visitor to Jalalabad in northeastern Afghanistan. It has been recorded as a vagrant in Syria,Saudi Arabia, Masirah Island, Qatar, Yemen, Socotra, Bahrain, where it was sighted in 1996 and in 2008, Lakshadweep islands, the Maldive Islands, and Turkey. In Kuwait, it is a common winter visitor at Green Island and farmlands near Al Jahra. In the 1970s, it was reported as a common winter visitor to the marshes and mudflats of Shadegan County in Iran. However, it is listed as resident in Iran.
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. In Oman, it is common in the Al Batinah Region and in cultivated areas east of the Sharqiya Sands below elevations of 1,000 m (3,300 ft). In India, it was sighted at elevations ranging from sea level in the Bhitarkanika Mangroves and the Gulf of Mannar to about 2,100 m (6,900 ft) in the Nilgiri Mountains.
The Indian roller is generally not very gregarious and is usually found alone or in pairs. 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.
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 3–9 m (10–30 ft) from where it flies down to forage for ground insects. It also uses higher perches in the upper canopy of trees. The display of the Indian roller is aerobatic with twists and turns. It is attracted by wildfires and darts into hot smoke in pursuit of insects. 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.
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), and flying at humans.
Haemoproteus coraciae live inside the red-blood cells and Leucocytozoon blood parasites have been recorded in the lung tissues. Parasitic helminth worms Hadjelia srivastavai, Cyrnea graphophasiani, Habronema thapari and Synhimantus spiralis have been recorded from the gizzards of Indian rollers.
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