Taxonomy and Systematics
This species was described by Linnaeus in 1758 and placed in the genus Ardea that included the larger herons. Edward Blyth published a monograph on the cranes in 1881 in which he considered the "Sarus Crane" of India to be made up of two species, Grus collaris and Grus antigone. Most modern authors recognise one species with three disjunct populations that have been treated as subspecies, although the status of one extinct population from the Philippines is uncertain. The nominate subspecies from India is the largest, and in the east from Myanmar is replaced by race sharpii that extends into the Southeast Asian islands. The nominate form from the Indian subcontinent is well marked and differentiated by having a white collar below the bare head and upper neck, and white tertiary remiges. Some authors consider antigone and sharpii as representatives of a formerly continuous population that varied clinally. The race in Australia, initially placed in sharpii (sometimes spelt sharpei but amended to conform to the rules of Latin grammar) has been separated and named as the race gilliae (sometimes spelt gillae or even gilli). The Australian race was designated only in 1988, with the species itself first noticed in Australia in 1969 and regarded as a recent immigrant. Native Australians, however, differentiated the Sarus and the Brolga and called the Sarus "the crane that dips its head in blood". The Australian race has a distinctively darker plumage and a larger grey patch of ear coverts. This race is the most recently diverged with an estimated 3000 generations of breeding within Australia. An additional subspecies luzonica has been suggested for the population once found, but now extinct, in the Philippines. It may be synonymous with either gilliae or sharpii.
Analysis of mitochondrial DNA, from a limited number of specimens, suggested that there was gene flow within the continental Asian populations until the 20th century reductions in range, and that Australia was colonized only in the Late Pleistocene, some 35000 years ago. This has been corroborated by nDNA microsatellite analyses with four times the sample size. This study further suggests that the Australian population is quite inbred. As there exists the possibility of (limited) hybridization with the genetically distinct Brolga, the Australian Sarus Crane can be expected to be an incipient species.
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