Rollers are 16 species of terrestrial birds in the family Coraciidae. Rollers occur in Africa, Eurasia, and Australia. Most species are tropical, but some occur in temperate climates.
Rollers are stout-bodied birds, ranging in body length from 9.5 to 13 in (24 to 33 cm). Most species have rounded wings, and a square or forked tail, although a few have elongated, decorative tail feathers. Rollers have a short neck and short legs with strong feet. Their beak is stout, broad, slightly downward curving, and hooked at the tip.
Rollers are generally attractive, brightly colored birds, with patches of brown, yellow, blue, purple, green, black, or white. The sexes do not differ in coloration. Rollers received their common name from the habit of many species performing aerial rolls and tumbles during their prenuptial display flights.
Many species of rollers feed by hunting from a conspicuous perch and making quick sallies to predate on insects, lizards, small mammals, or other suitable prey that they detect visually. Flying prey may be pursued aerially, or the rollers may seize their prey on the ground.
Rollers defend a territory by conspicuous visual displays, and not by song. Rollers nest in cavities in trees, earthen banks, or rock piles. The three to six eggs are incubated by both parents, who also rear the young together.
The most diverse genus is Coracias, nine species of which breed in Africa alone. The racquet-tailed roller (C. spatulata) is an especially attractive African species, having a pale-blue body, with violet and brown wings, and two elongated, outer tail feathers. The European roller (Coracias garrulus) is a migratory species of Europe, wintering in the tropics of Africa.
The dollarbird or broad-billed roller (Eurystomus orientalis) is a blue-bodied bird with white wing-patches. The dollarbird ranges widely from India and China, through Indonesia and New Guinea, to Australia and the Solomon Islands. Various subspecies of the dollarbird have evolved in some parts of its range.
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