The sarus crane (Antigone antigone) is a large nonmigratory crane found in parts of the Indian subcontinent, Southeast Asia, and northern Australia. The tallest of the flying birds, standing at a height of up to , they are a conspicuous species of open wetlands in South Asia, seasonally flooded Dipterocarpus forests in Southeast Asia, and Eucalyptus-dominated woodlands and grasslands in Australia.
The sarus crane is easily distinguished from other cranes in the region by its overall grey colour and the contrasting red head and upper neck. They forage on marshes and shallow wetlands for roots, tubers, insects, crustaceans, and small vertebrate prey. Like other cranes, they form long-lasting pair bonds and maintain territories within which they perform territorial and courtship displays that include loud trumpeting, leaps, and dance-like movements. In India, they are considered symbols of marital fidelity, believed to mate for life and pine the loss of their mates, even to the point of starving to death.
The main breeding season is during the wet season, when the pair builds an enormous nest "island," a circular platform of reeds and grasses nearly two meters in diameter and high enough to stay above the shallow water surrounding it. Increased agricultural intensity is often thought to have led to declines in sarus crane numbers, but the largest known population of Sarus cranes are in northern India's Uttar Pradesh where small-holder agriculture, favorable farmer attitudes, wet crops such as flooded paddy and the extensive network of canals has benefited the species. The stronghold of the species is in India, where it is traditionally revered and lives in agricultural lands in close proximity to humans. Elsewhere, the species has been extirpated in many parts of its former range.
Taxonomy In 1743 the English naturalist George Edwards included an illustration and a description of the sarus crane in the first volume of his A Natural History of Uncommon Birds. He used the English name "The Greater Indian Crane". Edwards based his hand-coloured etching on a live specimen that he had drawn at the London home of the Admiral Charles Wager. When in 1758 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the tenth edition, he placed the sarus crane (Grus major Indica in Latin) with the herons and cranes in the genus Ardea. Linnaeus included a brief description, coined the binomial name Ardea antigone and cited Edwards' work. The specific epithet is based on Greek mythology. Antigone was the daughter of the Trojan king Laomedon. She was turned into a stork for comparing her own beauty with the goddess Hera. Linnaeus appears to have confused this myth with that of Gerana, queen of the pigmies, who considered herself more beautiful than Hera and was turned into a crane. The sarus crane was formerly placed in the genus Grus, but a molecular phylogenetic study published in 2010 found that the genus, as then defined, was polyphyletic. In the resulting rearrangement to create monophyletic genera, four species, including the sarus crane, were placed in the resurrected genus Antigone that had originally been erected by German naturalist Ludwig Reichenbach in 1853.
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 recognize one species with three disjunct populations that are sometimes treated as subspecies, although the status of one extinct population from the Philippines is uncertain. The sarus cranes in India (referred to as A. a. antigone) are the largest, and in Myanmar to the east are replaced by a population that extends into Southeast Asia (referred to as A. a. sharpii). Sarus cranes from the Indian subcontinent are differentiated from the south-eastern population by the white collar below their bare head and upper neck, and their white tertiary flight feathers. The population in Australia (initially placed in A. a. sharpii (sometimes spelt sharpei but amended to conform to the rules of Latin grammar) was separated and named A. a. gilliae, sometimes spelt gillae or gillii), prior to a genetic analysis. A 2005 genetic analysis suggests that these three populations are representatives of a formerly continuous population that varied clinally. The Australian subspecies was designated only in 1988, with the species itself was first noticed in Australia in 1966 and regarded as a recent immigrant. Native Australians, however, differentiated between the sarus and the brolga, calling the sarus "the crane that dips its head in blood." Sarus cranes of the Australian population are similar to those in Southeast Asia in having no white on the neck and tertiary remiges, but are distinguished by a larger grey patch of ear coverts. The Australian population shows the most recent divergence from the ancestral form with an estimated 3000 generations of breeding within Australia. An additional subspecies, A. a. luzonica, was suggested for the population — now extinct — in the Philippines. No distinctive characteristic is known of this disappeared population.
Analysis of mitochondrial DNA from a limited number of specimens suggests that gene flow occurred within the continental Asian populations until the 20th-century reductions in range, and that Australia was colonized only in the Late Pleistocene, some 35,000 years ago. This has been corroborated by DNA microsatellite analyses on a large and widely distributed set of individuals in the sample. This study suggests further that the Australian population shows low genetic variability. 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.
The common name 'sarus' is from the Hindi name (sāras) for the species. The Hindi word is derived from the Sanskrit word sarasa for the "lake bird", (sometimes corrupted to sārhans). British soldiers in colonial India who hunted the birds corrupted the name to serious or even cyrus.
Description
The adult sarus crane is very large, with grey wings and body, a bare red head, collar and nape, a greyish crown, and a long, greenish-grey, pointed bill. In flight, the long neck is held straight, unlike that of a heron (which folds it back), and the black wing tips can be seen; the crane's long, pink legs trail behind them. This bird has a grey ear covert patch, orange-red irises, and a greenish-grey bill. Juveniles have a yellowish base to the bill and the brown-grey head is fully feathered.
The bare red skin of the adult's head and neck is brighter during the breeding season. This skin is rough and covered by feather follicles, and a narrow area around and behind the head is covered by black, bristly feathers. The sexes do not differ in plumage, although males are on average larger than females; males of the Indian population can attain a maximum height around , making them the world's tallest extant flying bird. The weight of nominate race individuals is , while five adults of A. a. sharpii averaged . Across the distribution range, their weight can vary from , height typically from , and wingspan from .
While individuals from northern Indian populations are among the heaviest cranes, alongside the red-crowned and wattled cranes, and the largest in their range, birds from Australia tend to be smaller. In Australia, the sarus can easily be mistaken for the more widespread brolga. The brolga has the red colouring confined to the head and not extending onto the neck. Body mass in Australian sarus cranes was found to average in males and in females, with a range for both sexes of . Thus, Australian sarus cranes average about 25% lighter than the northern counterparts and are marginally lighter on average than brolgas.
Distribution and habitat The species has historically been widely distributed on the lowlands of India along the Gangetic plains, extending south to the Godavari River, west to coastal Gujarat, the Tharparkar District of Pakistan, and east to West Bengal and Assam. The species no longer breeds in Punjab, though it winters regularly in the state. Sarus cranes are rare in West Bengal and Assam, and are no longer found in the state of Bihar. In Nepal, its distribution is restricted to the western and central lowland plains, with most of the population occurring in Rupandehi, Kapilvastu, and Nawalparasi districts.
Three distinct populations of sarus cranes were known in Southeast Asia: the northern population in China and Myanmar, the southern population in Cambodia and Vietnam, and the distinct, likely-extinct luzonica subspecies once found in the Philippines. The sarus used to extend to Thailand and further east into the Philippines, but may now be extinct in both these countries. In 2011, 24 captive-bred cranes raised from five founders were reintroduced into Thailand. A reasonably sized population of over 150 breeding pairs of sarus cranes has been discovered in the Ayeyarwadi delta, Myanmar, with additional cranes confirmed in the states of Kachin, Shan, and Rakhine. In Australia they are found only in the north-east, and are partly migratory in some areas. The global range has shrunk and the largest occupied area, and the largest known population, is in India. Increasing paddy fields accompanied by an increase in the network of irrigation canals during and prior to the Green Revolution may have facilitated increases in the distribution and numbers of sarus cranes due to an increase in reliable moisture levels in various locations in India. Although now found mainly at low elevations on the plains, some historical records exist from highland marshes further north in Harkit Sar and Kahag in Kashmir. The sarus crane breeds in some high elevation regions such as near the Pong Dam in Himachal Pradesh, where populations may be growing in response to increasing rice cultivation along the reservoir. In rice-dominated districts of Uttar Pradesh, sarus crane abundance (estimated as occupancy) was highest in the western districts, intermediate in the central districts, and minimal in the eastern districts. Sarus crane abundance was positively associated with percentage of wetlands on the landscape, and negatively with the percentage of area under rice cultivation.