<Tr> <Td_colspan="2"> <P> Ardea antigone protonym Grus antigone Grus collaris Boddaert, 1783 </P> </Td> </Tr> <P> Ardea antigone protonym Grus antigone Grus collaris Boddaert, 1783 </P> <P> The sarus crane (Antigone antigone) is a large non-migratory crane found in parts of the Indian Subcontinent, Southeast Asia and Australia . The tallest of the flying birds, standing at a height of up to 1.8 m (5 ft 11 in), they are conspicuous and iconic species of open wetlands . The sarus crane is easily distinguished from other cranes in the region by the 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 rainy season, when the pair builds an enormous nest "island", a circular platform of reeds and grasses nearly two metres in diameter and high enough to stay above the shallow water surrounding it . Sarus crane numbers have declined greatly in the last century and it has been suggested that the current population is a tenth or less (perhaps 2.5%) of the numbers that existed in the 1850s . 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 . </P> <P> The adult sarus crane is very large with grey wings and body; a bare red head and part of the upper neck; a greyish crown; and a long greenish - grey pointed bill . In flight, the long neck is held straight, unlike that of an 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, an orange - red iris and a greenish - grey bill . Juveniles have a yellowish base to the bill and the brown - grey head is fully feathered . </P>

Which is the tallest flying bird in the world known to mate with single partner for life