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The rollers are an Old World family, Coraciidae, of near passerine birds. The group gets its name from the aerial acrobatics some of these birds perform during courtship or territorial flights. Rollers resemble crows in size and build, and share the colourful appearance of kingfishers and bee-eaters, blues and pinkish or cinnamon browns predominating. The two inner front toes are connected, but not the outer one. They are mainly insect eaters, with ''Eurystomus'' species taking their prey on the wing, and those of the genus ''Coracias'' diving from a perch to catch food items from on the ground, like giant shrikes. Although living rollers are birds of warm climates in the Old World, fossil records show that rollers were present in North America during the Eocene. They are monogamous and nest in an unlined hole in a tree or in masonry, and lay 2–4 eggs in the tropics, 3–6 at higher latitudes. The eggs, which are white, hatch after 17–20 days, and the young remain in the nest for approximately another 30 days. ==Taxonomy== The roller family Coraciidae is one of nine in the order Coraciiformes, which also includes the motmots, bee-eaters, todies, ground-rollers, cuckoo roller and three families of kingfishers.〔Fry (1992) 6–27〕 Apart from the ground-rollers, these families do not appear to be particularly closely related to the rollers, and the Coraciiformes are therefore probably polyphyletic.〔Hackett, S. ''et al.'' (2008) "A phylogenomic study of birds reveals their evolutionary history " ''Science'' 320 (5884) 1763–1768〕 The division of the rollers into two genera is uncontroversial.〔 The eleven species are:〔 * Genus: ''Coracias'' * * European roller (''Coracias garrulus'') * * Abyssinian roller (''Coracias abyssinicus'') * * Lilac-breasted roller (''Coracias caudatus'') * * Racket-tailed roller (''Coracias spatulatus'') * * Rufous-crowned roller (''Coracias naevius'') * * Indian roller (''Coracias benghalensis'') * * Purple-winged roller (''Coracias temminckii'') * * Blue-bellied roller (''Coracias cyanogaster'') * Genus: ''Eurystomus'' * * Cinnamon roller (''Eurystomus glaucurus'') * * Blue-throated roller (''Eurystomus gularis'') * * Azure roller (''Eurystomus azureus'') * * Dollarbird (''Eurystomus orientalis'') The Coraciiformes family gets its scientific name for Latin ''coracium'', "like a raven", and the English name "roller" from the aerial acrobatics some of these birds perform during courtship or territorial flights. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「roller」の詳細全文を読む スポンサード リンク
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