The Oriental dollarbird (Eurystomus orientalis) is a bird of the roller family, so named because of the distinctive pale blue or white, coin-shaped spots on its wings. It can be found from Australia to Korea, Japan and India.
A molecular phylogenetic study published in 2018 found that the azure dollarbird (Eurystomus azureus) of the North Moluccas was nested in a clade containing subspecies of the Oriental dollarbird. Formerly, some authorities have considered the azure dollarbird to have been another subspecies of the oriental dollarbird.
E. o. irisi – Deraniyagala, 1951. Found in Sri Lanka
E. o. oberholseri – Junge, 1936. Found on Simeulue (off north-western Sumatra)
E. o. pacificus – (Latham, 1801). Originally described as a separate species in the genus Coracias. Found on the Lesser Sunda Islands, and northern and eastern Australia
E. o. solomonensis – Sharpe, 1890. Originally described as a separate species. Found in the Solomon Islands
Etymology
E. o. pacificus, wing-stretching to show the 'dollar' patch that gives it its name
The generic name derives from Ancient Greekeurustomos 'wide-mouthed' and the specific epithet is Latin orientalis 'eastern'.
The name "dollarbird" is from the round bluish-white patch on the wing, visible in flight or when stretching its wings, "said to resemble a silver dollar" (coin).
Alternative names for the oriental dollarbird include the Asian dollarbird, Australian roller (E. o. pacificus), dark roller, dollar roller, dollarbird, eastern broad-billed roller and oriental broad-billed roller.
Description
The oriental dollarbird 27–32cm long. It is dark brown but this is heavily washed with a bluish-green sheen on the back and wing coverts. Its belly and undertail coverts are light coloured, and it has glossy bright blue colouring on its throat and undertail. Its flight feathers are a darker blue. Its bill is short and wide and in mature animals is coloured orange-red with a black tip. It has very light blue-white patches on the outer parts of its wings which are highly visible in flight. The females are slightly duller than the males but overall the two are very similar. Immature birds are much duller than the adults and do not have the blue colouring on their throats. They also have dark blackish-grey to brown bills and feet instead of the red of the adults.
Distribution and habitat
The oriental dollarbird is found from Australia to Japan and India. At least two subspecies (E. o. cyanocollis and E. o. pacificus) are migratory; the former breeds in northeastern Asia and winters southeastern Asia, and the latter in northern and eastern Australia between the months of September and April and winters in New Guinea and nearby islands. The birds prefer open wooded areas with hole-bearing trees to build nests in.[citation needed]
Behaviour and ecology
The oriental dollarbird is most commonly seen singly with a distinctive upright silhouette on a bare branch high in a tree, from which it hawks for flying insects, often returning to the same perch after a few seconds.
Gallery
E. o. cyanocollis, juvenile with dull bill, at Rangapur near Dhansar River, Nepal
Kaeng Krachan Nat'l Park - Thailand
E. o. pacificus pair, Rush Creek, SE Queensland, Australia
↑Johansson, U.S.; Irestedt, M.; Qu, Y.; Ericson, P. G. P. (2018). "Phylogenetic relationships of rollers (Coraciidae) based on complete mitochondrial genomes and fifteen nuclear genes". Molecular Phylogenetics and Evolution. 126: 17–22. Bibcode:2018MolPE.126...17J. doi:10.1016/j.ympev.2018.03.030. PMID29631051. S2CID5011292.
12Kazmierczak, Krys; Perlo, Ber van (2000). A field guide to the birds of the Indian subcontinent. New Haven: Yale University Press. p.164. ISBN0-300-07921-4.
↑Fry, C. Hilary; Fry, Kathie; Harris, Alan (1992). "Dollarbird". Kingfishers, Bee-eaters, and Rollers. London: Christopher Helm. pp.305–308. ISBN978-0-7136-8028-7.
12Simpson, Ken; Day, Nicolas (2010). Field guide to the birds of Australia. Camberwell, Vic: Penguin. p.164. ISBN978-0-670-07231-6.