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cuckoo roller
The cuckoo roller or courol (''Leptosomus discolor'')〔del Hoyo, J. Elliott, A. & Sargatal, J. (2001)〕 is the only bird in the family Leptosomidae, which is usually placed in the order Coraciiformes, which also includes the kingfishers, bee-eaters and rollers. However, its position is not very clear. Morphological evidence may suggest a placement in or near to Falconiformes. In the rather comprehensive DNA study by Hackett ''et al'',〔Hacket ''et al''. (2008)〕 this and the hoatzin are the only two birds whose position is unclear, although the cuckoo roller seems to be at the root of a group that contains the Trogoniformes, Bucerotiformes, Piciformes, and Coraciiformes.
It is a medium-large bird, inhabiting forests and woodlands in Madagascar and the Comoro Islands. Three subspecies are described: the nominate ''L. d. discolor'' is found in Madagascar and Mayotte Island, ''L. d. intermedius'' on Anjouan, and ''L. d. gracilis'' of Grand Comoro. Based on its smaller size, differences in the plumage, and minor difference in the voice, the last of these is sometimes considered a separate species, the Comoro cuckoo roller (''L. gracilis'').
==Description==
The cuckoo roller has a total length of ; the nominate subspecies is the largest, and ''L. d. gracilis'' the smallest. Unlike the true rollers and ground rollers, where the sexes have identical appearance, the cuckoo roller is sexually dichromatic. Males have a mostly velvety grey chest and head, changing gradually to white on the remaining underparts (the demarcation between grey and white is stronger in ''L. d. gracilis''). The back, tail, and wing-coverts are dark iridescent green with a purplish tinge (especially on the wing-coverts), and the crown and eye-stripe are black. Females are mostly brown, with strongly dark-spotted pale underparts (less spotting in ''L. d. gracilis''). Juveniles are generally reported as resembling a dull female, but at least juveniles of ''L. d. gracilis'' are sexually dimorphic, and this also possibly applies to the other subspecies. The bill is stout and the eyes are set far back in the face. The legs and feet are small, and the feet have an unusual structure which has confused many ornithologists, but is now thought to be zygodactylous (two toes forwards, two toes backwards).〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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